MC68HC908GZ16 MC68HC908GZ8 Data Sheet M68HC08 Microcontrollers MC68HC908GZ16 Rev. 4.0 10/2006 freescale.com

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MC68HC908GZ16 MC68HC908GZ8 Data Sheet To provide the most up-to-date information, the revision of our documents on the World Wide Web will be the most current. Your printed copy may be an earlier revision. To verify you have the latest information available, refer to: http://freescale.com/ Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. This product incorporates SuperFlash® technology licensed from SST. ©Freescale Semiconductor, Inc., 2005, 2006. All rights reserved. MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 3

Revision History The following revision history table summarizes changes contained in this document. For your convenience, the page number designators have been linked to the appropriate location. Revision History Revision Page Date Description Level Number(s) February, N/A Initial release N/A 2003 Reorganized to meet latest publication standards for M68HC08 Family N/A documentation Added Table1-1. Summary of Device Variations 19 Figure5-2. Configuration Register 1 (CONFIG1) — Changed bit 0 from 80 SCIBDSRC to ESCIBDSRC. Chapter 15 Enhanced Serial Communications Interface (ESCI) Module — 181–212 Updated with additional data Chapter 17 Serial Peripheral Interface (SPI) Module — Removed all references N/A October, to DMAS 1.0 2004 Added DC injection current values to: 21.5 5-Vdc Electrical Characteristics 289 21.6 3.3-Vdc Electrical Characteristics 291 21.15 Memory Characteristics — Updated table entries 302 Corrected ICG references to CGM throughout document. N/A Chapter 22 Ordering Information and Mechanical Specifications — Corrected 303 device ordering information Added the following: Appendix A MC68HC908GZ8 311–314 205 — Corrected Functionality entries 205 June, 2.0 15.9.1 ESCI Arbiter Control Register — Corrected bit ACLK bit description 209 2005 15.9.3 Bit Time Measurement — Corrected definition for ACLK bit 210 March, 10.5 Clock Generator Module (CGM) — Updated description to remove 3.0 110 2006 erroneous information. 1.6 Unused Pin Termination — Added new section. 26 12.2 Features — Corrected timer link connection from TIM2 channel 0 to TIM1 121 channel 0. 12.9 Timer Link — Corrected timer link connection from TIM2 channel 0 to TIM1 October, 133 4.0 channel 0. 2006 13.1 Introduction — Replaced note with unused pin termination text. 155 21.5 5-Vdc Electrical Characteristics and 289 21.6 3.3-Vdc Electrical Characteristics — Updated DC injection current 291 specification. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 4 Freescale Semiconductor

List of Chapters Chapter 1 General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Chapter 2 Memory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 Chapter 3 Analog-to-Digital Converter (ADC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47 Chapter 4 Clock Generator Module (CGM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59 Chapter 5 Configuration Register (CONFIG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79 Chapter 6 Computer Operating Properly (COP) Module. . . . . . . . . . . . . . . . . . . . . . . . . . .83 Chapter 7 Central Processor Unit (CPU). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87 Chapter 8 External Interrupt (IRQ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99 Chapter 9 Keyboard Interrupt Module (KBI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103 Chapter 10 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109 Chapter 11 Low-Voltage Inhibit (LVI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117 Chapter 12 MSCAN08 Controller (MSCAN08). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121 Chapter 13 Input/Output (I/O) Ports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .155 Chapter 14 Resets and Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169 Chapter 15 Enhanced Serial Communications Interface (ESCI) Module. . . . . . . . . . . . .181 Chapter 16 System Integration Module (SIM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .213 Chapter 17 Serial Peripheral Interface (SPI) Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . .231 Chapter 18 Timebase Module (TBM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251 Chapter 19 Timer Interface Module (TIM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .255 Chapter 20 Development Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .271 Chapter 21 Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .287 Chapter 22 Ordering Information and Mechanical Specifications . . . . . . . . . . . . . . . . . .303 Appendix A MC68HC908GZ8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .311 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 5

List of Chapters MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 6 Freescale Semiconductor

Table of Contents Chapter 1 General Description 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 1.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 1.2.1 Standard Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 1.2.2 Features of the CPU08 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 1.3 MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 1.4 Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 1.5 Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1.5.1 Power Supply Pins (V and V ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 DD SS 1.5.2 Oscillator Pins (OSC1 and OSC2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1.5.3 External Reset Pin (RST). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1.5.4 External Interrupt Pin (IRQ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1.5.5 CGM Power Supply Pins (V and V ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 DDA SSA 1.5.6 External Filter Capacitor Pin (V ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 CGMXFC 1.5.7 ADC Power Supply/Reference Pins (V /V and V /V ). . . . . . . . . . . . . . . . 25 DDAD REFH SSAD REFL 1.5.8 Port A Input/Output (I/O) Pins (PTA7/KBD7–PTA0/KBD0) . . . . . . . . . . . . . . . . . . . . . . . . . 25 1.5.9 Port B I/O Pins (PTB7/AD7–PTB0/AD0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1.5.10 Port C I/O Pins (PTC6–PTC0/CANTX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1.5.11 Port D I/O Pins (PTD7/T2CH1–PTD0/SS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1.5.12 Port E I/O Pins (PTE5–PTE2, PTE1/RxD, and PTE0/TxD). . . . . . . . . . . . . . . . . . . . . . . . . 26 1.6 Unused Pin Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Chapter 2 Memory 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.2 Unimplemented Memory Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.3 Reserved Memory Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.4 Input/Output (I/O) Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.5 Random-Access Memory (RAM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2.6 FLASH Memory (FLASH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2.6.1 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2.6.2 FLASH Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 2.6.3 FLASH Page Erase Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 2.6.4 FLASH Mass Erase Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.6.5 FLASH Program/Read Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.6.6 FLASH Block Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 2.6.7 FLASH Block Protect Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 2.6.8 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2.6.9 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 7

Table of Contents Chapter 3 Analog-to-Digital Converter (ADC) 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3.3 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3.3.1 ADC Port I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3.3.2 Voltage Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3.3.3 Conversion Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.3.4 Conversion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.3.5 Accuracy and Precision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.3.6 Result Justification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.4 Monotonicity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.6 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.7 I/O Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.7.1 ADC Analog Power Pin (V ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 DDAD 3.7.2 ADC Analog Ground Pin (V ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 SSAD 3.7.3 ADC Voltage Reference High Pin (V ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 REFH 3.7.4 ADC Voltage Reference Low Pin (V ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 REFL 3.7.5 ADC Voltage In (V ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 ADIN 3.8 I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.8.1 ADC Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.8.2 ADC Data Register High and Data Register Low. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.8.2.1 Left Justified Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.8.2.2 Right Justified Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.8.2.3 Left Justified Signed Data Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 3.8.2.4 Eight Bit Truncation Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 3.8.3 ADC Clock Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Chapter 4 Clock Generator Module (CGM) 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.3 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.3.1 Crystal Oscillator Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.3.2 Phase-Locked Loop Circuit (PLL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.3.3 PLL Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.3.4 Acquisition and Tracking Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.3.5 Manual and Automatic PLL Bandwidth Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.3.6 Programming the PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.3.7 Special Programming Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 4.3.8 Base Clock Selector Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 4.3.9 CGM External Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 8 Freescale Semiconductor

4.4 I/O Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.4.1 Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.4.2 Crystal Amplifier Output Pin (OSC2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.4.3 External Filter Capacitor Pin (CGMXFC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.4.4 PLL Analog Power Pin (V ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 DDA 4.4.5 PLL Analog Ground Pin (V ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 SSA 4.4.6 Oscillator Enable Signal (SIMOSCEN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.4.7 Oscillator Stop Mode Enable Bit (OSCSTOPENB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.4.8 Crystal Output Frequency Signal (CGMXCLK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.4.9 CGM Base Clock Output (CGMOUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.4.10 CGM CPU Interrupt (CGMINT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.5 CGM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.5.1 PLL Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 4.5.2 PLL Bandwidth Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 4.5.3 PLL Multiplier Select Register High . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 4.5.4 PLL Multiplier Select Register Low . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 4.5.5 PLL VCO Range Select Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 4.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 4.7 Special Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.7.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.7.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.7.3 CGM During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.8 Acquisition/Lock Time Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.8.1 Acquisition/Lock Time Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.8.2 Parametric Influences on Reaction Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 4.8.3 Choosing a Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Chapter 5 Configuration Register (CONFIG) 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 5.2 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Chapter 6 Computer Operating Properly (COP) Module 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 6.2 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 6.3 I/O Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 6.3.1 CGMXCLK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 6.3.2 STOP Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 6.3.3 COPCTL Write. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 6.3.4 Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 6.3.5 Internal Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 6.3.6 Reset Vector Fetch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.3.7 COPD (COP Disable). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.3.8 COPRS (COP Rate Select) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.4 COP Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.6 Monitor Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 9

Table of Contents 6.7 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.7.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.7.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 6.8 COP Module During Break Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Chapter 7 Central Processor Unit (CPU) 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 7.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 7.3 CPU Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 7.3.1 Accumulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 7.3.2 Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 7.3.3 Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 7.3.4 Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 7.3.5 Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 7.4 Arithmetic/Logic Unit (ALU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 7.5 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 7.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 7.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 7.6 CPU During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 7.7 Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 7.8 Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Chapter 8 External Interrupt (IRQ) 8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 8.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 8.3 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 8.4 IRQ Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 8.5 IRQ Module During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 8.6 IRQ Status and Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Chapter 9 Keyboard Interrupt Module (KBI) 9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 9.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 9.3 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 9.4 Keyboard Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 9.5 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 9.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 9.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 9.6 Keyboard Module During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 9.7 I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 9.7.1 Keyboard Status and Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 9.7.2 Keyboard Interrupt Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 10 Freescale Semiconductor

Chapter 10 Low-Power Modes 10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10.1.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10.1.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10.2 Analog-to-Digital Converter (ADC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10.2.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10.2.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 10.3 Break Module (BRK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 10.3.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 10.3.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 10.4 Central Processor Unit (CPU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 10.4.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 10.4.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 10.5 Clock Generator Module (CGM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 10.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 10.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 10.6 Computer Operating Properly Module (COP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.7 External Interrupt Module (IRQ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.7.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.7.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.8 Keyboard Interrupt Module (KBI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.8.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.8.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.9 Low-Voltage Inhibit Module (LVI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.9.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.9.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.10 Enhanced Serial Communications Interface Module (ESCI). . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.10.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.10.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.11 Serial Peripheral Interface Module (SPI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.11.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.11.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 10.12 Timer Interface Module (TIM1 and TIM2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 10.12.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 10.12.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 10.13 Timebase Module (TBM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 10.13.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 10.13.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 10.14 MSCAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 10.14.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 10.14.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 10.15 Exiting Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 10.16 Exiting Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 11

Table of Contents Chapter 11 Low-Voltage Inhibit (LVI) 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 11.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 11.3 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 11.3.1 Polled LVI Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 11.3.2 Forced Reset Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 11.3.3 Voltage Hysteresis Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 11.3.4 LVI Trip Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 11.4 LVI Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 11.5 LVI Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 11.6 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 11.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 11.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Chapter 12 MSCAN08 Controller (MSCAN08) 12.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 12.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 12.3 External Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 12.4 Message Storage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 12.4.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 12.4.2 Receive Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 12.4.3 Transmit Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 12.5 Identifier Acceptance Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 12.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 12.6.1 Interrupt Acknowledge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 12.6.2 Interrupt Vectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 12.7 Protocol Violation Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 12.8 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 12.8.1 MSCAN08 Sleep Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 12.8.2 MSCAN08 Soft Reset Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 12.8.3 MSCAN08 Power-Down Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 12.8.4 CPU Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 12.8.5 Programmable Wakeup Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 12.9 Timer Link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 12.10 Clock System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 12.11 Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 12.12 Programmer’s Model of Message Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 12.12.1 Message Buffer Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 12.12.2 Identifier Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 12.12.3 Data Length Register (DLR). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 12.12.4 Data Segment Registers (DSRn). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 12.12.5 Transmit Buffer Priority Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 12.13 Programmer’s Model of Control Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 12.13.1 MSCAN08 Module Control Register 0. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 12.13.2 MSCAN08 Module Control Register 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 12 Freescale 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12.13.3 MSCAN08 Bus Timing Register 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 12.13.4 MSCAN08 Bus Timing Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 12.13.5 MSCAN08 Receiver Flag Register (CRFLG). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 12.13.6 MSCAN08 Receiver Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 12.13.7 MSCAN08 Transmitter Flag Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 12.13.8 MSCAN08 Transmitter Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 12.13.9 MSCAN08 Identifier Acceptance Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 12.13.10 MSCAN08 Receive Error Counter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 12.13.11 MSCAN08 Transmit Error Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 12.13.12 MSCAN08 Identifier Acceptance Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 12.13.13 MSCAN08 Identifier Mask Registers (CIDMR0–CIDMR3). . . . . . . . . . . . . . . . . . . . . . . . . 153 Chapter 13 Input/Output (I/O) Ports 13.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 13.2 Unused Pin Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 13.3 Port A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 13.3.1 Port A Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 13.3.2 Data Direction Register A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 13.3.3 Port A Input Pullup Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 13.4 Port B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 13.4.1 Port B Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 13.4.2 Data Direction Register B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 13.5 Port C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 13.5.1 Port C Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 13.5.2 Data Direction Register C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 13.5.3 Port C Input Pullup Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 13.6 Port D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 13.6.1 Port D Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 13.6.2 Data Direction Register D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 13.6.3 Port D Input Pullup Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 13.7 Port E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 13.7.1 Port E Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 13.7.2 Data Direction Register E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 Chapter 14 Resets and Interrupts 14.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 14.2 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 14.2.1 Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 14.2.2 External Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 14.2.3 Internal Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 14.2.3.1 Power-On Reset (POR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 14.2.3.2 Computer Operating Properly (COP) Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 14.2.3.3 Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 14.2.3.4 Illegal Opcode Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 14.2.3.5 Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 14.2.4 System Integration Module (SIM) Reset Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . 171 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 13

Table of Contents 14.3 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 14.3.1 Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 14.3.2 Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 14.3.2.1 Software Interrupt (SWI) Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 14.3.2.2 Break Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 14.3.2.3 IRQ Pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 14.3.2.4 Clock Generator (CGM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 14.3.2.5 Timer Interface Module 1 (TIM1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 14.3.2.6 Timer Interface Module 2 (TIM2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 14.3.2.7 Serial Peripheral Interface (SPI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 14.3.2.8 Serial Communications Interface (SCI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 14.3.2.9 KBD0–KBD7 Pins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 14.3.2.10 Analog-to-Digital Converter (ADC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 14.3.2.11 Timebase Module (TBM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 14.3.2.12 MSCAN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 14.3.3 Interrupt Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 14.3.3.1 Interrupt Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 14.3.3.2 Interrupt Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 14.3.3.3 Interrupt Status Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 Chapter 15 Enhanced Serial Communications Interface (ESCI) Module 15.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 15.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 15.3 Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 15.4 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 15.4.1 Data Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 15.4.2 Transmitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 15.4.2.1 Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 15.4.2.2 Character Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 15.4.2.3 Break Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 15.4.2.4 Idle Characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 15.4.2.5 Inversion of Transmitted Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 15.4.2.6 Transmitter Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 15.4.3 Receiver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 15.4.3.1 Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 15.4.3.2 Character Reception. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 15.4.3.3 Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 15.4.3.4 Framing Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 15.4.3.5 Baud Rate Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192 15.4.3.6 Receiver Wakeup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 15.4.3.7 Receiver Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 15.4.3.8 Error Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 15.5 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 15.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 15.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 15.6 ESCI During Break Module Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 14 Freescale Semiconductor

15.7 I/O Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 15.7.1 PTE0/TxD (Transmit Data). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 15.7.2 PTE1/RxD (Receive Data). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 15.8 I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 15.8.1 ESCI Control Register 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 15.8.2 ESCI Control Register 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 15.8.3 ESCI Control Register 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 15.8.4 ESCI Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 15.8.5 ESCI Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 15.8.6 ESCI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 15.8.7 ESCI Baud Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 15.8.8 ESCI Prescaler Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206 15.9 ESCI Arbiter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 15.9.1 ESCI Arbiter Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 15.9.2 ESCI Arbiter Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 15.9.3 Bit Time Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 15.9.4 Arbitration Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 Chapter 16 System Integration Module (SIM) 16.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 16.2 SIM Bus Clock Control and Generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 16.2.1 Bus Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 16.2.2 Clock Startup from POR or LVI Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 16.2.3 Clocks in Stop Mode and Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 16.3 Reset and System Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 16.3.1 External Pin Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 16.3.2 Active Resets from Internal Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 16.3.2.1 Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 16.3.2.2 Computer Operating Properly (COP) Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 16.3.2.3 Illegal Opcode Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 16.3.2.4 Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 16.3.2.5 Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 16.3.2.6 Monitor Mode Entry Module Reset (MODRST) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 16.4 SIM Counter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 16.4.1 SIM Counter During Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 16.4.2 SIM Counter During Stop Mode Recovery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 16.4.3 SIM Counter and Reset States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 16.5 Exception Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 16.5.1 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 16.5.1.1 Hardware Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 16.5.1.2 SWI Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 16.5.1.3 Interrupt Status Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 16.5.2 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 16.5.3 Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 16.5.4 Status Flag Protection in Break Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 15

Table of Contents 16.6 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 16.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 16.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 16.7 SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 16.7.1 Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 16.7.2 SIM Reset Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 16.7.3 Break Flag Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 Chapter 17 Serial Peripheral Interface (SPI) Module 17.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 17.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 17.3 Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 17.4 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 17.4.1 Master Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 17.4.2 Slave Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 17.5 Transmission Formats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 17.5.1 Clock Phase and Polarity Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 17.5.2 Transmission Format When CPHA = 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 17.5.3 Transmission Format When CPHA = 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 17.5.4 Transmission Initiation Latency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 17.6 Queuing Transmission Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 17.7 Error Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 17.7.1 Overflow Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 17.7.2 Mode Fault Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 17.8 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 17.9 Resetting the SPI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 17.10 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 17.10.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 17.10.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 17.11 SPI During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 17.12 I/O Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 17.12.1 MISO (Master In/Slave Out). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 17.12.2 MOSI (Master Out/Slave In). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 17.12.3 SPSCK (Serial Clock) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 17.12.4 SS (Slave Select). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 17.12.5 CGND (Clock Ground). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 17.13 I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 17.13.1 SPI Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 17.13.2 SPI Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 17.13.3 SPI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 Chapter 18 Timebase Module (TBM) 18.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 18.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 18.3 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 16 Freescale Semiconductor

18.4 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 18.5 TBM Interrupt Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 18.6 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 18.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 18.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 18.7 Timebase Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 Chapter 19 Timer Interface Module (TIM) 19.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 19.2 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 19.3 Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 19.4 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 19.4.1 TIM Counter Prescaler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 19.4.2 Input Capture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 19.4.3 Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 19.4.3.1 Unbuffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 19.4.3.2 Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 19.4.4 Pulse Width Modulation (PWM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 19.4.4.1 Unbuffered PWM Signal Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 19.4.4.2 Buffered PWM Signal Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 19.4.4.3 PWM Initialization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 19.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 19.6 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 19.6.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 19.6.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 19.7 TIM During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 19.8 I/O Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 19.9 I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 19.9.1 TIM Status and Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 19.9.2 TIM Counter Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266 19.9.3 TIM Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 19.9.4 TIM Channel Status and Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 19.9.5 TIM Channel Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270 Chapter 20 Development Support 20.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 20.2 Break Module (BRK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 20.2.1 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 20.2.1.1 Flag Protection During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 20.2.1.2 TIM During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 20.2.1.3 COP During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 20.2.2 Break Module Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 20.2.2.1 Break Status and Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 20.2.2.2 Break Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 20.2.2.3 Break Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 20.2.2.4 Break Flag Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 17

Table of Contents 20.2.3 Low-Power Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 20.3 Monitor ROM (MON) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 20.3.1 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276 20.3.1.1 Normal Monitor Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.3.1.2 Forced Monitor Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.3.1.3 Monitor Vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.3.1.4 Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 20.3.1.5 Break Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 20.3.1.6 Baud Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 20.3.1.7 Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 20.3.2 Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 Chapter 21 Electrical Specifications 21.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 21.2 Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 21.3 Functional Operating Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288 21.4 Thermal Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288 21.5 5-Vdc Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 21.6 3.3-Vdc Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291 21.7 5.0-Volt Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293 21.8 3.3-Volt Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293 21.9 Clock Generation Module Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 21.9.1 CGM Component Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 21.9.2 CGM Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 21.10 5.0-Volt ADC Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 21.11 3.3-Volt ADC Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 21.12 5.0-Volt SPI Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 21.13 3.3-Volt SPI Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 21.14 Timer Interface Module Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 21.15 Memory Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 Chapter 22 Ordering Information and Mechanical Specifications 22.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 22.2 MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 22.3 Package Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 Appendix A MC68HC908GZ8 A.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 A.2 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 A.3 Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 A.4 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 18 Freescale Semiconductor

Chapter 1 General Description 1.1 Introduction The MC68HC908GZ16 is a member of the low-cost, high-performance M68HC08 Family of 8-bit microcontroller units (MCUs). All MCUs in the family use the enhanced M68HC08 central processor unit (CPU08) and are available with a variety of modules, memory sizes and types, and package types. 0. Table 1-1. Summary of Device Variations Device Memory Size MC68HC908QZ16 16 Kbytes user FLASH MC68HC908GZ8 8 Kbytes user FLASH The information contained in this document pertains to both the MC68HC908GZ16 and the MC68HC908GZ8 with the exceptions shown Appendix A MC68HC908GZ8 1.2 Features For convenience, features have been organized to reflect: (cid:129) Standard features (cid:129) Features of the CPU08 1.2.1 Standard Features Features include: (cid:129) High-performance M68HC08 architecture optimized for C-compilers (cid:129) Fully upward-compatible object code with M6805, M146805, and M68HC05 Families (cid:129) 8-MHz internal bus frequency (cid:129) Clock generation module supporting 1-MHz to 8-MHz crystals (cid:129) MSCAN08 (implementing 2.0b protocol as defined in BOSCH specification dated September 1991) (cid:129) FLASH program memory security(1) (cid:129) On-chip programming firmware for use with host personal computer which does not require high voltage for entry (cid:129) In-system programming (ISP) 1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult for unauthorized users. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 19

General Description (cid:129) System protection features: – Optional computer operating properly (COP) reset – Low-voltage detection with optional reset and selectable trip points for 3.3-V and 5.0-V operation – Illegal opcode detection with reset – Illegal address detection with reset (cid:129) Low-power design; fully static with stop and wait modes (cid:129) Standard low-power modes of operation: – Wait mode – Stop mode (cid:129) Master reset pin and power-on reset (POR) (cid:129) On-chip FLASH memory: – MC68HC908GZ16 — 16 Kbytes – MC68HC908GZ8 — 8 Kbytes (cid:129) 1 Kbyte of on-chip random-access memory (RAM) (cid:129) 406 bytes of FLASH programming routines read-only memory (ROM) (cid:129) Serial peripheral interface (SPI) module (cid:129) Enhanced serial communications interface (ESCI) module (cid:129) Fine adjust baud rate prescalers for precise control of baud rate (cid:129) Arbiter module: – Measurement of received bit timings for baud rate recovery without use of external timer – Bitwise arbitration for arbitrated UART communications (cid:129) LIN specific enhanced features: – Generation of LIN 1.2 break symbols without extra software steps on each message – Break detection filtering to prevent false interrupts (cid:129) Two 16-bit, 2-channel timer interface modules (TIM1 and TIM2) with selectable input capture, output compare, and pulse-width modulation (PWM) capability on each channel. One 2-channel timer and one 1-channel timer on the 32-pin package. (cid:129) Up to 8-channel, 10-bit successive approximation analog-to-digital converter (ADC) depending on package choice (cid:129) BREAK (BRK) module to allow single breakpoint setting during in-circuit debugging (cid:129) Internal pullups on IRQ and RST to reduce customer system cost (cid:129) Up to 37 general-purpose input/output (I/O) pins, including: – 28 shared-function I/O pins – Up to nine dedicated I/O pins, depending on package choice (cid:129) Selectable pullups on inputs only on ports A, C, and D. Selection is on an individual port bit basis. During output mode, pullups are disengaged. (cid:129) High current 10-mA sink/source capability on all port pins (cid:129) Higher current 20-mA sink/source capability on PTC0–PTC4 (cid:129) Timebase module (TBM) with clock prescaler circuitry for eight user selectable periodic real-time interrupts with optional active clock source during stop mode for periodic wakeup from stop using an external crystal (cid:129) User selection of having the oscillator enabled or disabled during stop mode (cid:129) Up to 8-bit keyboard wakeup port depending on package choice (cid:129) 2 mA maximum current injection on all port pins to maintain input protection (cid:129) Available packages: – 32-pin quad flat pack (LQFP) – 48-pin quad flat pack (LQFP) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 20 Freescale Semiconductor

MCU Block Diagram (cid:129) Specific features of the MC68HC908GZ16 in 32-pin LQFP are: – Port A is only 4 bits: PTA0–PTA3; 4-pin keyboard interrupt (KBI) module – Port B is only 6 bits: PTB0–PTB5; 6-channel ADC module – Port C is only 2 bits: PTC0–PTC1; shared with MSCAN08 module – Port D is only 7 bits: PTD0–PTD6; shared with SPI, TIM1, and TIM2 modules – Port E is only 2 bits: PTE0–PTE1; shared with ESCI module (cid:129) Specific features of the MC68HC908GZ16 in 48-pin LQFP are: – Port A is 8 bits: PTA0–PTA7; 8-pin KBI module – Port B is 8 bits: PTB0–PTB7; 8-channel ADC module – Port C is only 7 bits: PTC0–PTC6; shared with MSCAN08 module – Port D is 8 bits: PTD0–PTD7; shared with SPI, TIM1, and TIM2 modules – Port E is only 6 bits: PTE0–PTE5; shared with ESCI module 1.2.2 Features of the CPU08 Features of the CPU08 include: (cid:129) Enhanced HC05 programming model (cid:129) Extensive loop control functions (cid:129) 16 addressing modes (eight more than the HC05) (cid:129) 16-bit index register and stack pointer (cid:129) Memory-to-memory data transfers (cid:129) Fast 8 × 8 multiply instruction (cid:129) Fast 16/8 divide instruction (cid:129) Binary-coded decimal (BCD) instructions (cid:129) Optimization for controller applications (cid:129) Efficient C language support 1.3 MCU Block Diagram Figure 1-1 shows the structure of the MC68HC908GZ16. 1.4 Pin Assignments Figure 1-2 and Figure 1-3 illustrate the pin assignments for the 32-pin LQFP and 48-pin LQFP respectively. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 21

General Description INTERNAL BUS M68HC08 CPU REGCISPTUERS ARITUHNMIET T(AICL/ULO)GIC PROGRAMMMOADBULLEE TIMEBASE DDRA PORTA PPTTAA70//KKBBDD70–(1) PTB7/AD7 SINGLE BREAKPOINT CONTROL AND STATUS REGISTERS — 64 BYTES PTB6/AD6 BREAK MODULE PTB5/AD5 USER FLASH — 15,872 BYTES LOWD-UVAOLL TVAOGLETA INGHEIBIT DDRB PORTB PPTTBB43//AADD43 MODULE PTB2/AD2 USER RAM — 1024 BYTES PTB1/AD1 8-BIT KEYBOARD PTB0/AD0 MONITOR ROM — 350 BYTES INTERRUPT MODULE PTC6(1) PTC5(1) FLASH PROGRAMMING ROUTINES ROM — 406 BYTES 2-CHANNEL TIMER USER FLASH VECTOR SPACE — 44 BYTES INTERFACE MODULE 1 DDRC PORTC PPPTTTCCC432(((111))),,, (((222))) 2-CHANNEL TIMER INTERFACE MODULE 2 PTC1/CANRX(1), (2) CLOCK GENERATOR MODULE PTC0/CAN (1), (2) TX OSC1 1–8 MHz OSCILLATOR ENHANCED SERIAL OSC2 COMUNICATIONS PTD7/T2CH1(1) PHASE LOCKED LOOP INTERFACE MODULE PTD6/T2CH0(1) CGMXFC PTD5/T1CH1(1) RST(3) SYSTEM INTEGRATION COPMRPOUPTEERRL YO MPEORDAUTLIENG DDRD PORTD PPPTTTDDD243///MTS1POCSSHCI(0K1()(11)) MODULE SERIAL PERIPHERAL PTD1/MISO(1) INTERFACE MODULE PTD0/SS(1) IRQ(3) SINGLE EXTERNAL INTERRUPT MODULE PTE5–PTE2 VVDDAD//VVREFH 10-CBOITN AVNEARLTOEGR- TMOO-DDUIGLIETAL MONITOR MODULE DDRE PORTE PPTTEE10//RTxxDD DDAD REFL MEMORY MAP MODULE POWER-ON RESET MODULE SECURITY CONFIGURATION MODULE VDD REGISTER 1–2 VSS POWER MODULE V DDA V MONITOR MODE ENTRY SSA MSCAN08 MODULE MODULE 1. Ports are software configurable with pullup device if input port. 2. Higher current drive port pins 3. Pin contains integrated pullup device Figure 1-1. MCU Block Diagram MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 22 Freescale Semiconductor

Pin Assignments OSC1 OSC2 CGMXFC VSSA VDDA PTC1/CANRX PTC0/CANTX PTA3/KBD3 2 3 1 0 9 8 7 6 5 RST 1 3 3 2 2 2 2 224 PTA2/KBD2 PTE0/TxD 2 23 PTA1/KBD1 PTE1/RxD 3 22 PTA0/KBD0 IRQ 4 21 V /V SSAD REFL PTD0/SS 5 20 V /V DDAD REFH PTD1/MISO 6 19 PTB5/AD5 PTD2/MOSI 7 18 PTB4/AD4 PTD3/SPSCK 8 17 PTB3/AD3 0 1 2 3 4 5 6 9 1 1 1 1 1 1 1 VSS VDD CH0 CH1 CH0 AD0 AD1 AD2 D4/T1 D5/T1 D6/T2 PTB0/ PTB1/ PTB2/ T T T P P P Figure 1-2. 32-Pin LQFP Pin Assignments OSC1 OSC2 CGMXFC VSSA VDDA PTC1/CANRX PTC0/CANTX PTA7/KBD7 PTA6/KBD6 PTA5/KBD5 PTA4/KBD4 PTA3/KBD3 8 7 4 3 RST 1 47 46 45 44 43 42 41 40 39 38 36 PTA2/KBD2 PTE0/TxD 2 35 PTA1/KBD1 PTE1/RxD 3 34 PTA0/KBD0 PTE2 4 33 PTC6 PTE3 5 32 PTC5 PTE4 6 31 VSSAD/VREFL PTE5 7 30 VDDAD/VREFH IRQ 8 29 PTB7/AD7 PTD0/SS 9 28 PTB6/AD6 PTD1/MISO 10 27 PTB5/AD5 PTD2/MOSI 11 26 PTB4/AD4 PTD3/SPSCK 12 14 15 16 17 18 19 20 21 22 23 25 PTB3/AD3 13 24 VSS VDD CH0 CH1 CH0 CH1 TC2 TC3 TC4 AD0 AD1 AD2 D4/T1 D5/T1 D6/T2 D7/T2 P P P PTB0/ PTB1/ PTB2/ T T T T P P P P Figure 1-3. 48-Pin LQFP Pin Assignments MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 23

General Description 1.5 Pin Functions Descriptions of the pin functions are provided here. 1.5.1 Power Supply Pins (V and V ) DD SS V and V are the power supply and ground pins. The MCU operates from a single power supply. DD SS Fast signal transitions on MCU pins place high, short-duration current demands on the power supply. To prevent noise problems, take special care to provide power supply bypassing at the MCU as Figure 1-4 shows. Place the C1 bypass capacitor as close to the MCU as possible. Use a high-frequency-response ceramic capacitor for C1. C2 is an optional bulk current bypass capacitor for use in applications that require the port pins to source high current levels. MCU V V DD SS C1 0.1 μF + C2 V DD Note: Component values shown represent typical applications. Figure 1-4. Power Supply Bypassing 1.5.2 Oscillator Pins (OSC1 and OSC2) OSC1 and OSC2 are the connections for an external crystal, resonator, or clock circuit. See Chapter 4 Clock Generator Module (CGM). 1.5.3 External Reset Pin (RST) A logic 0 on the RST pin forces the MCU to a known startup state. RST is bidirectional, allowing a reset of the entire system. It is driven low when any internal reset source is asserted. This pin contains an internal pullup resistor. See Chapter 16 System Integration Module (SIM). 1.5.4 External Interrupt Pin (IRQ) IRQ is an asynchronous external interrupt pin. This pin contains an internal pullup resistor. See Chapter 8 External Interrupt (IRQ). MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 24 Freescale Semiconductor

Pin Functions 1.5.5 CGM Power Supply Pins (V and V ) DDA SSA V and V are the power supply pins for the analog portion of the clock generator module (CGM). DDA SSA Decoupling of these pins should be as per the digital supply. See Chapter 4 Clock Generator Module (CGM). 1.5.6 External Filter Capacitor Pin (V ) CGMXFC CGMXFC is an external filter capacitor connection for the CGM. See Chapter 4 Clock Generator Module (CGM). 1.5.7 ADC Power Supply/Reference Pins (V /V and V /V ) DDAD REFH SSAD REFL V and V are the power supply pins to the analog-to-digital converter (ADC). V and V DDAD SSAD REFH REFL are the reference voltage pins for the ADC. V is the high reference supply for the ADC, and by default REFH the V /V pin should be externally filtered and connected to the same voltage potential as V . DDAD REFH DD V is the low reference supply for the ADC, and by default the V /V pin should be connected REFL SSAD REFL to the same voltage potential as V . See Chapter 3 Analog-to-Digital Converter (ADC). SS 1.5.8 Port A Input/Output (I/O) Pins (PTA7/KBD7–PTA0/KBD0) PTA7–PTA0 are general-purpose, bidirectional I/O port pins. Any or all of the port A pins can be programmed to serve as keyboard interrupt pins. PTA7–PTA4 are only available on the 48-pin LQFP package. See Chapter 13 Input/Output (I/O) Ports and Chapter 9 Keyboard Interrupt Module (KBI). These port pins also have selectable pullups when configured for input mode. The pullups are disengaged when configured for output mode. The pullups are selectable on an individual port bit basis. 1.5.9 Port B I/O Pins (PTB7/AD7–PTB0/AD0) PTB7–PTB0 are general-purpose, bidirectional I/O port pins that can also be used for analog-to-digital converter (ADC) inputs. PTB7–PTB4 are only available on the 48-pin LQFP package. See Chapter 13 Input/Output (I/O) Ports and Chapter 3 Analog-to-Digital Converter (ADC). 1.5.10 Port C I/O Pins (PTC6–PTC0/CAN ) TX PTC6 and PTC5 are general-purpose, bidirectional I/O port pins. PTC4–PTC0 are general-purpose, bidirectional I/O port pins that contain higher current sink/source capability. PTC6–PTC2 are only available on the 48-pin LQFP package. See Chapter 13 Input/Output (I/O) Ports and Chapter 12 MSCAN08 Controller (MSCAN08). PTC1 and PTC0 can be programmed to be MSCAN08 pins. These port pins also have selectable pullups when configured for input mode. The pullups are disengaged when configured for output mode. The pullups are selectable on an individual port bit basis. 1.5.11 Port D I/O Pins (PTD7/T2CH1–PTD0/SS) PTD7–PTD0 are special-function, bidirectional I/O port pins. PTD3–PTD0 can be programmed to be serial peripheral interface (SPI) pins, while PTD7–PTD4 can be individually programmed to be timer interface module (TIM1 and TIM2) pins. PTD7 is only available on the 48-pin LQFP package. See Chapter 19 Timer Interface Module (TIM), Chapter 17 Serial Peripheral Interface (SPI) Module, and Chapter 13 Input/Output (I/O) Ports. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 25

General Description These port pins also have selectable pullups when configured for input mode. The pullups are disengaged when configured for output mode. The pullups are selectable on an individual port bit basis. 1.5.12 Port E I/O Pins (PTE5–PTE2, PTE1/RxD, and PTE0/TxD) PTE5–PTE0 are general-purpose, bidirectional I/O port pins. PTE1 and PTE0 can also be programmed to be enhanced serial communications interface (ESCI) pins. PTE5–PTE2 are only available on the 48-pin LQFP package. See Chapter 15 Enhanced Serial Communications Interface (ESCI) Module and Chapter 13 Input/Output (I/O) Ports. 1.6 Unused Pin Termination Input pins and I/O port pins that are not used in the application must be terminated. This prevents excess current caused by floating inputs, and enhances immunity during noise or transient events. Termination methods include: 1. Configuring unused pins as outputs and driving high or low; 2. Configuring unused pins as inputs and enabling internal pull-ups; 3. Configuring unused pins as inputs and using external pull-up or pull-down resistors. Never connect unused pins directly to V or V . DD SS Since some general-purpose I/O pins are not available on all packages, these pins must be terminated as well. Either method 1 or 2 above are appropriate. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 26 Freescale Semiconductor

Chapter 2 Memory 2.1 Introduction The CPU08 can address 64 Kbytes of memory space. The memory map, shown in Figure 2-1, includes: (cid:129) 15,872 bytes of user FLASH memory (cid:129) 1024 bytes of random-access memory (RAM) (cid:129) 406 bytes of FLASH programming routines read-only memory (ROM) (cid:129) 44 bytes of user-defined vectors (cid:129) 350 bytes of monitor ROM 2.2 Unimplemented Memory Locations Accessing an unimplemented location can cause an illegal address reset. In the memory map (Figure 2-1) and in register figures in this document, unimplemented locations are shaded. 2.3 Reserved Memory Locations Accessing a reserved location can have unpredictable effects on microcontroller (MCU) operation. In the Figure 2-1 and in register figures in this document, reserved locations are marked with the word Reserved or with the letter R. 2.4 Input/Output (I/O) Section Most of the control, status, and data registers are in the zero page area of $0000–$003F. Additional I/O registers have these addresses: (cid:129) $FE00; break status register, SBSR (cid:129) $FE01; SIM reset status register, SRSR (cid:129) $FE02; break auxiliary register, BRKAR (cid:129) $FE03; break flag control register, BFCR (cid:129) $FE04; interrupt status register 1, INT1 (cid:129) $FE05; interrupt status register 2, INT2 (cid:129) $FE06; interrupt status register 3, INT3 (cid:129) $FE07; reserved (cid:129) $FE08; FLASH control register, FLCR (cid:129) $FE09; break address register high, BRKH (cid:129) $FE0A; break address register low, BRKL (cid:129) $FE0B; break status and control register, BRKSCR (cid:129) $FE0C; LVI status register, LVISR (cid:129) $FF7E; FLASH block protect register, FLBPR Data registers are shown in Figure 2-2. Table 2-1 is a list of vector locations. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 27

Memory $0000 $FE03 BREAK FLAG CONTROL REGISTER (BFCR) I/O REGISTERS ↓ $FE04 INTERRUPT STATUS REGISTER 1 (INT1) 64 BYTES $003F $FE05 INTERRUPT STATUS REGISTER 2 (INT2) $0040 $FE06 INTERRUPT STATUS REGISTER 3 (INT3) RAM ↓ $FE07 RESERVED 1024 BYTES $043F $FE08 FLASH CONTROL REGISTER (FLCR) $0440 $FE09 BREAK ADDRESS REGISTER HIGH (BRKH) UNIMPLEMENTED ↓ $FE0A BREAK ADDRESS REGISTER LOW (BRKL) 192 BYTES $04FF $FE0B BREAK STATUS AND CONTROL REGISTER (BRKSCR) $0500 $FE0C LVI STATUS REGISTER (LVISR) MSCAN08 CONTROL AND MESSAGE BUFFER ↓ $FE0D 128 BYTES UNIMPLEMENTED $057F ↓ 3 BYTES $0580 $FE0F UNIMPLEMENTED ↓ $FE10 UNIMPLEMENTED 5760 BYTES 16 BYTES $1BFF ↓ RESERVED FOR COMPATIBILITY WITH MONITOR CODE $1C00 $FE1F FOR A-FAMILY PART FLASH PROGRAMMING ROUTINES ROM ↓ $FE20 406 BYTES MONITOR ROM $1D95 ↓ 350 BYTES $1D96 $FF7D UNIMPLEMENTED ↓ $FF7E FLASH BLOCK PROTECT REGISTER (FLBPR) 41,578 BYTES $BFFF $FF7F UNIMPLEMENTED $C000 ↓ 85 BYTES FLASH MEMORY ↓ $FFD3 15,872 BYTES $FDFF $FFD4 FLASH VECTORS $FE00 BREAK STATUS REGISTER (BSR) ↓ 44 BYTES $FE01 SIM RESET STATUS REGISTER (SRSR) $FFFF(1) $FE02 BREAK AUXILIARY REGISTER (BRKAR) 1. $FFF6–$FFFD used for eight security bytes Figure 2-1. Memory Map MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 28 Freescale Semiconductor

Input/Output (I/O) Section Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: Port A Data Register PTA7 PTA6 PTA5 PTA4 PTA3 PTA2 PTA1 PTA0 $0000 (PTA) Write: See page 158. Reset: Unaffected by reset Read: Port B Data Register PTB7 PTB6 PTB5 PTB4 PTB3 PTB2 PTB1 PTB0 $0001 (PTB) Write: See page 160. Reset: Unaffected by reset Read: 1 Port C Data Register PTC6 PTC5 PTC4 PTC3 PTC2 PTC1 PTC0 $0002 (PTC) Write: See page 162. Reset: Unaffected by reset Read: Port D Data Register PTD7 PTD6 PTD5 PTD4 PTD3 PTD2 PTD1 PTD0 $0003 (PTD) Write: See page 164. Reset: Unaffected by reset Read: Data Direction Register A DDRA7 DDRA6 DDRA5 DDRA4 DDRA3 DDRA2 DDRA1 DDRA0 $0004 (DDRA) Write: See page 158. Reset: 0 0 0 0 0 0 0 0 Read: Data Direction Register B DDRB7 DDRB6 DDRB5 DDRB4 DDRB3 DDRB2 DDRB1 DDRB0 $0005 (DDRB) Write: See page 161. Reset: 0 0 0 0 0 0 0 0 Read: 0 Data Direction RegisterC DDRC6 DDRC5 DDRC4 DDRC3 DDRC2 DDRC1 DDRC0 $0006 (DDRC) Write: See page 162. Reset: 0 0 0 0 0 0 0 0 Read: Data Direction Register D DDRD7 DDRD6 DDRD5 DDRD4 DDRD3 DDRD2 DDRD1 DDRD0 $0007 (DDRD) Write: See page 165. Reset: 0 0 0 0 0 0 0 0 Read: 0 0 Port E Data Register PTE5 PTE4 PTE3 PTE2 PTE1 PTE0 $0008 (PTE) Write: See page 167. Reset: Unaffected by reset Read: ESCI Prescaler Register PDS2 PDS1 PDS0 PSSB4 PSSB3 PSSB2 PSSB1 PSSB0 $0009 (SCPSC) Write: See page 206. Reset: 0 0 0 0 0 0 0 0 Read: ALOST AFIN ARUN AOVFL ARD8 ESCI Arbiter Control AM1 AM0 ACLK $000A Register (SCIACTL) Write: See page 209. Reset: 0 0 0 0 0 0 0 0 Read: ESCI Arbiter Data ARD7 ARD6 ARD5 ARD4 ARD3 ARD2 ARD1 ARD0 $000B Register (SCIADAT) Write: See page 210. Reset: 0 0 0 0 0 0 0 0 =Unimplemented R = Reserved U = Unaffected Figure 2-2. Control, Status, and Data Registers (Sheet 1 of 8) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 29

Memory Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 Data Direction Register E DDRE5 DDRE4 DDRE3 DDRE2 DDRE1 DDRE0 $000C (DDRE) Write: See page 168. Reset: 0 0 0 0 0 0 0 0 Read: Port A Input Pullup Enable PTAPUE7 PTAPUE6 PTAPUE5 PTAPUE4 PTAPUE3 PTAPUE2 PTAPUE1 PTAPUE0 $000D Register (PTAPUE) Write: See page 159. Reset: 0 0 0 0 0 0 0 0 Read: 0 Port C Input Pullup Enable PTCPUE6 PTCPUE5 PTCPUE4 PTCPUE3 PTCPUE2 PTCPUE1 PTCPUE0 $000E Register (PTCPUE) Write: See page 164. Reset: 0 0 0 0 0 0 0 0 Read: Port D Input Pullup Enable PTDPUE7 PTDPUE6 PTDPUE5 PTDPUE4 PTDPUE3 PTDPUE2 PTDPUE1 PTDPUE0 $000F Register (PTDPUE) Write: See page 166. Reset: 0 0 0 0 0 0 0 0 Read: SPI Control Register (SPCR) SPRIE R SPMSTR CPOL CPHA SPWOM SPE SPTIE $0010 Write: See page 247. Reset: 0 0 1 0 1 0 0 0 Read: SPRF OVRF MODF SPTE SPI Status and Control ERRIE MODFEN SPR1 SPR0 $0011 Register (SPSCR) Write: See page 249. Reset: 0 0 0 0 1 0 0 0 Read: R7 R6 R5 R4 R3 R2 R1 R0 SPI Data Register $0012 (SPDR) Write: T7 T6 T5 T4 T3 T2 T1 T0 See page 250. Reset: Unaffected by reset Read: ESCI Control Register 1 LOOPS ENSCI TXINV M WAKE ILTY PEN PTY $0013 (SCC1) Write: See page 196. Reset: 0 0 0 0 0 0 0 0 Read: ESCI Control Register 2 SCTIE TCIE SCRIE ILIE TE RE RWU SBK $0014 (SCC2) Write: See page 198. Reset: 0 0 0 0 0 0 0 0 Read: R8 ESCI Control Register 3 T8 R R ORIE NEIE FEIE PEIE $0015 (SCC3) Write: See page 200. Reset: U 0 0 0 0 0 0 0 Read: SCTE TC SCRF IDLE OR NF FE PE ESCI Status Register 1 $0016 (SCS1) Write: See page 201. Reset: 1 1 0 0 0 0 0 0 Read: BKF RPF ESCI Status Register 2 $0017 (SCS2) Write: See page 203. Reset: 0 0 0 0 0 0 0 0 =Unimplemented R = Reserved U = Unaffected Figure 2-2. Control, Status, and Data Registers (Sheet 2 of 8) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 30 Freescale Semiconductor

Input/Output (I/O) Section Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: R7 R6 R5 R4 R3 R2 R1 R0 ESCI Data Register $0018 (SCDR) Write: T7 T6 T5 T4 T3 T2 T1 T0 See page 204. Reset: Unaffected by reset Read: ESCI Baud Rate Register LINT LINR SCP1 SCP0 R SCR2 SCR1 SCR0 $0019 (SCBR) Write: See page 204. Reset: 0 0 0 0 0 0 0 0 Keyboard Status Read: 0 0 0 0 KEYF 0 IMASKK MODEK and Control Register $001A Write: ACKK (INTKBSCR) See page 107. Reset: 0 0 0 0 0 0 0 0 Read: Keyboard Interrupt Enable KBIE7 KBIE6 KBIE5 KBIE4 KBIE3 KBIE2 KBIE1 KBIE0 $001B Register (INTKBIER) Write: See page 108. Reset: 0 0 0 0 0 0 0 0 Read: TBIF 0 Timebase Module Control TBR2 TBR1 TBR0 TBIE TBON R $001C Register (TBCR) Write: TACK See page 254. Reset: 0 0 0 0 0 0 0 0 Read: 0 0 0 0 IRQF 0 IRQ Status and Control IMASK MODE $001D Register (INTSCR) Write: ACK See page 102. Reset: 0 0 0 0 0 0 0 0 Configuration Register 2 Read: 0 0 0 0 OSCENIN- ESCIBD- $001E (CONFIG2)(1) Write: MSCANEN TMCLKSEL STOP SRC See page 79. Reset: 0 0 0 0 0 0 0 1 Configuration Register 1 Read: LVI5OR3 COPRS LVISTOP LVIRSTD LVIPWRD SSREC STOP COPD $001F (CONFIG1)(1) Write: (Note 1) See page 80. Reset: 0 0 0 0 0 0 0 0 1. One-time writable register after each reset, except LVI5OR3 bit. LVI5OR3 bit is only reset via POR (power-on reset). Read: TOF 0 0 Timer 1 Status and Control TOIE TSTOP PS2 PS1 PS0 $0020 Register (T1SC) Write: 0 TRST See page 265. Reset: 0 0 1 0 0 0 0 0 Read: Bit 15 14 13 12 11 10 9 Bit 8 Timer 1 Counter $0021 Register High (T1CNTH) Write: See page 266. Reset: 0 0 0 0 0 0 0 0 Read: Bit 7 6 5 4 3 2 1 Bit 0 Timer 1 Counter $0022 Register Low (T1CNTL) Write: See page 266. Reset: 0 0 0 0 0 0 0 0 Read: Timer 1 Counter Modulo Bit 15 14 13 12 11 10 9 Bit 8 $0023 Register High (T1MODH) Write: See page 267. Reset: 1 1 1 1 1 1 1 1 =Unimplemented R = Reserved U = Unaffected Figure 2-2. Control, Status, and Data Registers (Sheet 3 of 8) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 31

Memory Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: Timer 1 Counter Modulo Bit 7 6 5 4 3 2 1 Bit 0 $0024 Register Low (T1MODL) Write: See page 267. Reset: 1 1 1 1 1 1 1 1 Read: CH0F Timer 1 Channel 0 Status and CH0IE MS0B MS0A ELS0B ELS0A TOV0 CH0MAX $0025 Control Register (T1SC0) Write: 0 See page 267. Reset: 0 0 0 0 0 0 0 0 Read: Timer 1 Channel 0 Bit 15 14 13 12 11 10 9 Bit 8 $0026 Register High (T1CH0H) Write: See page 270. Reset: Indeterminate after reset Read: Timer 1 Channel 0 Bit 7 6 5 4 3 2 1 Bit 0 $0027 Register Low (T1CH0L) Write: See page 270. Reset: Indeterminate after reset Read: CH1F 0 Timer 1 Channel 1 Status and CH1IE MS1A ELS1B ELS1A TOV1 CH1MAX $0028 Control Register (T1SC1) Write: 0 See page 267. Reset: 0 0 0 0 0 0 0 0 Read: Timer 1 Channel 1 Bit 15 14 13 12 11 10 9 Bit 8 $0029 Register High (T1CH1H) Write: See page 270. Reset: Indeterminate after reset Read: Timer 1 Channel 1 Bit 7 6 5 4 3 2 1 Bit 0 $002A Register Low (T1CH1L) Write: See page 270. Reset: Indeterminate after reset Read: TOF 0 0 Timer 2 Status and Control TOIE TSTOP PS2 PS1 PS0 $002B Register (T2SC) Write: 0 TRST See page 265. Reset: 0 0 1 0 0 0 0 0 Read: Bit 15 14 13 12 11 10 9 Bit 8 Timer 2 Counter $002C Register High (T2CNTH) Write: See page 266. Reset: 0 0 0 0 0 0 0 0 Read: Bit 7 6 5 4 3 2 1 Bit 0 Timer 2 Counter $002D Register Low (T2CNTL) Write: See page 266. Reset: 0 0 0 0 0 0 0 0 Read: Timer 2 Counter Modulo Bit 15 14 13 12 11 10 9 Bit 8 $002E Register High (T2MODH) Write: See page 267. Reset: 1 1 1 1 1 1 1 1 Read: Timer 2 Counter Modulo Bit 7 6 5 4 3 2 1 Bit 0 $002F Register Low (T2MODL) Write: See page 267. Reset: 1 1 1 1 1 1 1 1 =Unimplemented R = Reserved U = Unaffected Figure 2-2. Control, Status, and Data Registers (Sheet 4 of 8) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 32 Freescale Semiconductor

Input/Output (I/O) Section Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: CH0F Timer 2 Channel 0 Status and CH0IE MS0B MS0A ELS0B ELS0A TOV0 CH0MAX $0030 Control Register (T2SC0) Write: 0 See page 267. Reset: 0 0 0 0 0 0 0 0 Read: Timer 2 Channel 0 Bit 15 14 13 12 11 10 9 Bit 8 $0031 Register High (T2CH0H) Write: See page 270. Reset: Indeterminate after reset Read: Timer 2 Channel 0 Bit 7 6 5 4 3 2 1 Bit 0 $0032 Register Low (T2CH0L) Write: See page 270. Reset: Indeterminate after reset Read: CH1F 0 Timer 2 Channel 1 Status and CH1IE MS1A ELS1B ELS1A TOV1 CH1MAX $0033 Control Register (T2SC1) Write: 0 See page 267. Reset: 0 0 0 0 0 0 0 0 Read: Timer 2 Channel 1 Bit 15 14 13 12 11 10 9 Bit 8 $0034 Register High (T2CH1H) Write: See page 270. Reset: Indeterminate after reset Read: Timer 2 Channel 1 Bit 7 6 5 4 3 2 1 Bit 0 $0035 Register Low (T2CH1L) Write: See page 270. Reset: Indeterminate after reset Read: PLLF PLL Control Register PLLIE PLLON BCS R R VPR1 VPR0 $0036 (PCTL) Write: See page 69. Reset: 0 0 1 0 0 0 0 0 Read: LOCK 0 0 0 0 PLL Bandwidth Control AUTO ACQ R $0037 Register (PBWC) Write: See page 71. Reset: 0 0 0 0 0 0 0 0 Read: 0 0 0 0 PLL Multiplier Select High MUL11 MUL10 MUL9 MUL8 $0038 Register (PMSH) Write: See page 72. Reset: 0 0 0 0 0 0 0 0 Read: PLL Multiplier Select Low MUL7 MUL6 MUL5 MUL4 MUL3 MUL2 MUL1 MUL0 $0039 Register (PMSL) Write: See page 73. Reset: 0 0 0 0 U U U U Read: PLL VCO Select Range VRS7 VRS6 VRS5 VRS4 VRS3 VRS2 VRS1 VRS0 $003A Register (PMRS) Write: See page 73. Reset: 0 1 0 0 0 0 0 0 Read: 0 0 0 0 R R R R $003B Reserved Write: Reset: 0 0 0 0 0 0 0 1 =Unimplemented R = Reserved U = Unaffected Figure 2-2. Control, Status, and Data Registers (Sheet 5 of 8) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 33

Memory Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: ADC Status and Control COCO AIEN ADCO ADCH4 ADCH3 ADCH2 ADCH1 ADCH0 $003C Register (ADSCR) Write: See page 53. Reset: 0 0 0 1 1 1 1 1 Read: 0 0 0 0 0 0 AD9 AD8 ADC Data High Register $003D (ADRH) Write: See page 55. Reset: Unaffected by reset Read: AD7 AD6 AD5 AD4 A3 AD2 AD1 AD0 ADC Data Low Register $003E (ADRL) Write: See page 55. Reset: Unaffected by reset Read: 0 ADC Clock Register ADIV2 ADIV1 ADIV0 ADICLK MODE1 MODE0 R $003F (ADCLK) Write: See page 57. Reset: 0 0 0 0 0 1 0 0 $0500 MSCAN08 Control MSCAN08 control registers (9 bytes) ↓ Registers Refer to 12.13 Programmer’s Model of Control Registers $0508 See page 141. $0509 ↓ Reserved Reserved (5 bytes) $050D $050E MSCAN08 ↓ MSCAN08 error counters (2 bytes) Error Counters $050F $0510 MSCAN08 MSCAN08 control registers (9 bytes) ↓ Identifier Filter Refer to 12.13 Programmer’s Model of Control Registers $0517 See page 141. $0518 ↓ Reserved Reserved (40 bytes) $053F $0540 MSCAN08 MSC08 receive buffer ↓ Receive Buffer Refer to 12.12 Programmer’s Model of Message Storage $054F See page 137. $0550 MSCAN08 Transmit Buffer 0 MSC08 transmitter buffer 0 ↓ See page 137. Refer to 12.12 Programmer’s Model of Message Storage $055F =Unimplemented R = Reserved U = Unaffected Figure 2-2. Control, Status, and Data Registers (Sheet 6 of 8) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 34 Freescale Semiconductor

Input/Output (I/O) Section Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 $0560 MSCAN08 Transmit Buffer 1 MSC08 transmitter buffer 1 ↓ See page 137. Refer to 12.12 Programmer’s Model of Message Storage $056F $0570 MSCAN08 Transmit Buffer 2 MSC08 transmitter buffer 2 ↓ See page 137. Refer to 12.12 Programmer’s Model of Message Storage $057F Read: SBSW Break Status Register R R R R R R R $FE00 (BSR) Write: (Note 1) See page 275. Reset: 0 0 0 0 0 0 0 0 1. Writing a logic 0 clears SBSW. Read: POR PIN COP ILOP ILAD MODRST LVI 0 SIM Reset Status Register $FE01 (SRSR) Write: See page 228. POR: 1 0 0 0 0 0 0 0 Read: R R R R R R R R $FE02 Reserved Write: Reset: 0 0 0 0 0 0 0 0 Read: Break Flag Control BCFE R R R R R R R $FE03 Register (BFCR) Write: See page 275. Reset: 0 0 0 0 0 0 0 0 Read: IF6 IF5 IF4 IF3 IF2 IF1 0 0 Interrupt Status Register1 $FE04 (INT1) Write: R R R R R R R R See page 180. Reset: 0 0 0 0 0 0 0 0 Read: IF14 IF13 IF12 IF11 IF10 IF9 IF8 IF7 Interrupt Status Register2 $FE05 (INT2) Write: R R R R R R R R See page 180. Reset: 0 0 0 0 0 0 0 0 Read: 0 0 IF20 IF19 IF18 IF17 IF16 IF15 Interrupt Status Register3 $FE06 (INT3) Write: R R R R R R R R See page 180. Reset: 0 0 0 0 0 0 0 0 Read: R R R R R R R R $FE07 Reserved Write: Reset: 0 0 0 0 0 0 0 0 Read: 0 0 0 0 FLASH Control Register HVEN MASS ERASE PGM $FE08 (FLCR) Write: See page 39. Reset: 0 0 0 0 0 0 0 0 Read: Break Address Register High Bit 15 14 13 12 11 10 9 Bit 8 $FE09 (BRKH) Write: See page 274. Reset: 0 0 0 0 0 0 0 0 =Unimplemented R = Reserved U = Unaffected Figure 2-2. Control, Status, and Data Registers (Sheet 7 of 8) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 35

Memory Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: Break Address Register Low Bit 7 6 5 4 3 2 1 Bit 0 $FE0A (BRKL) Write: See page 274. Reset: 0 0 0 0 0 0 0 0 Read: 0 0 0 0 0 0 Break Status and Control BRKE BRKA $FE0B Register (BRKSCR) Write: See page 274. Reset: 0 0 0 0 0 0 0 0 Read: LVIOUT 0 0 0 0 0 0 0 LVI Status Register (LVISR) $FE0C Write: See page 119. Reset: 0 0 0 0 0 0 0 0 Read: FLASH Block Protect BPR7 BPR6 BPR5 BPR4 BPR3 BPR2 BPR1 BPR0 $FF7E Register (FLBPR)(3) Write: See page 44. Reset: Unaffected by reset 3. Nonvolatile FLASH register Read: Low byte of reset vector COP Control Register $FFFF (COPCTL) Write: Writing clears COP counter (any value) See page 85. Reset: Unaffected by reset =Unimplemented R = Reserved U = Unaffected Figure 2-2. Control, Status, and Data Registers (Sheet 8 of 8) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 36 Freescale Semiconductor

Input/Output (I/O) Section . Table 2-1. Vector Addresses Vector Priority Vector Address Vector Lowest $FFD4 MSCAN08 Transmit Vector (High) IF20 $FFD5 MSCAN08 Transmit Vector (Low) $FFD6 MSCAN08 Receive Vector (High) IF19 $FFD7 MSCAN08 Receive Vector (Low) $FFD8 MSCAN08 Error Vector (High) IF18 $FFD9 MSCAN08 Error Vector (Low) $FFDA MSCAN08 Wakeup Vector (High) IF17 $FFDB MSCAN08 Wakeup Vector (Low) $FFDC Timebase Vector (High) IF16 $FFDD Timebase Vector (Low) $FFDE ADC Conversion Complete Vector (High) IF15 $FFDF ADC Conversion Complete Vector (Low) $FFE0 Keyboard Vector (High) IF14 $FFE1 Keyboard Vector (Low) $FFE2 ESCI Transmit Vector (High) IF13 $FFE3 ESCI Transmit Vector (Low) $FFE4 ESCI Receive Vector (High) IF12 $FFE5 ESCI Receive Vector (Low) $FFE6 ESCI Error Vector (High) IF11 $FFE7 ESCI Error Vector (Low) $FFE8 SPI Transmit Vector (High) IF10 $FFE9 SPI Transmit Vector (Low) $FFEA SPI Receive Vector (High) IF9 $FFEB SPI Receive Vector (Low) $FFEC TIM2 Overflow Vector (High) IF8 $FFED TIM2 Overflow Vector (Low) $FFEE TIM2 Channel 1 Vector (High) IF7 $FFEF TIM2 Channel 1 Vector (Low) $FFF0 TIM2 Channel 0 Vector (High) IF6 $FFF1 TIM2 Channel 0 Vector (Low) $FFF2 TIM1 Overflow Vector (High) IF5 $FFF3 TIM1 Overflow Vector (Low) $FFF4 TIM1 Channel 1 Vector (High) IF4 $FFF5 TIM1 Channel 1 Vector (Low) $FFF6 TIM1 Channel 0 Vector (High) IF3 $FFF7 TIM1 Channel 0 Vector (Low) $FFF8 PLL Vector (High) IF2 $FFF9 PLL Vector (Low) $FFFA IRQ Vector (High) IF1 $FFFB IRQ Vector (Low) $FFFC SWI Vector (High) — $FFFD SWI Vector (Low) $FFFE Reset Vector (High) — Highest $FFFF Reset Vector (Low) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 37

Memory 2.5 Random-Access Memory (RAM) Addresses $0040 through $043F are RAM locations. The location of the stack RAM is programmable. The 16-bit stack pointer allows the stack to be anywhere in the 64-Kbyte memory space. NOTE For correct operation, the stack pointer must point only to RAM locations. Within page zero are 192 bytes of RAM. Because the location of the stack RAM is programmable, all page zero RAM locations can be used for I/O control and user data or code. When the stack pointer is moved from its reset location at $00FF out of page zero, direct addressing mode instructions can efficiently access all page zero RAM locations. Page zero RAM, therefore, provides ideal locations for frequently accessed global variables. Before processing an interrupt, the CPU uses five bytes of the stack to save the contents of the CPU registers. NOTE For M6805 compatibility, the H register is not stacked. During a subroutine call, the CPU uses two bytes of the stack to store the return address. The stack pointer decrements during pushes and increments during pulls. NOTE Be careful when using nested subroutines. The CPU may overwrite data in the RAM during a subroutine or during the interrupt stacking operation. 2.6 FLASH Memory (FLASH) This subsection describes the operation of the embedded FLASH memory. This memory can be read, programmed, and erased from a single external supply. The program, erase, and read operations are enabled through the use of an internal charge pump. It is recommended that the user utilize the FLASH programming routines provided in the on-chip ROM, which are described more fully in a separate application note. 2.6.1 Functional Description The FLASH memory is an array of 15,872 bytes with an additional 44 bytes of user vectors and one byte of block protection. An erased bit reads as logic 1 and a programmed bit reads as a logic 0. Memory in the FLASH array is organized into two rows per page basis. For the 16-K word by 8-bit embedded FLASH memory, the page size is 64 bytes per page and the row size is 32 bytes per row. Hence the minimum erase page size is 64 bytes and the minimum program row size is 32 bytes. Program and erase operation operations are facilitated through control bits in FLASH control register (FLCR). Details for these operations appear later in this section. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 38 Freescale Semiconductor

FLASH Memory (FLASH) The address ranges for the user memory and vectors are: (cid:129) $C000–$FDFF; user memory (cid:129) $FE08; FLASH control register (cid:129) $FF7E; FLASH block protect register (cid:129) $FFD4–$FFFF; these locations are reserved for user-defined interrupt and reset vectors Programming tools are available from Freescale Semiconductor. Contact your local representative for more information. NOTE A security feature prevents viewing of the FLASH contents.(1) 2.6.2 FLASH Control Register The FLASH control register (FLCR) controls FLASH program and erase operations. Address: $FE08 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 HVEN MASS ERASE PGM Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 2-3. FLASH Control Register (FLCR) HVEN — High-Voltage Enable Bit This read/write bit enables the charge pump to drive high voltages for program and erase operations in the array. HVEN can only be set if either PGM = 1 or ERASE = 1 and the proper sequence for program or erase is followed. 1 = High voltage enabled to array and charge pump on 0 = High voltage disabled to array and charge pump off MASS — Mass Erase Control Bit Setting this read/write bit configures the 16-Kbyte FLASH array for mass erase operation. 1 = MASS erase operation selected 0 = PAGE erase operation selected ERASE — Erase Control Bit This read/write bit configures the memory for erase operation. ERASE is interlocked with the PGM bit such that both bits cannot be equal to 1 or set to 1 at the same time. 1 = Erase operation selected 0 = Erase operation unselected PGM — Program Control Bit This read/write bit configures the memory for program operation. PGM is interlocked with the ERASE bit such that both bits cannot be equal to 1 or set to 1 at the same time. 1 = Program operation selected 0 = Program operation unselected 1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult for unauthorized users. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 39

Memory 2.6.3 FLASH Page Erase Operation Use this step-by-step procedure to erase a page (64 bytes) ofFLASH memory to read as logic 1. A page consists of 64 consecutive bytes starting from addresses $XX00, $XX40, $XX80, or $XXC0. The 44-byte user interrupt vectors area also forms a page. Any FLASH memory page can be erased alone. 1. Set the ERASE bit, and clear the MASS bit in the FLASH control register. 2. Read the FLASH block protect register. 3. Write any data to any FLASH location within the page address range of the block to be desired. 4. Wait for a time, t (minimum 10 μs) NVS 5. Set the HVEN bit. 6. Wait for a time, t (minimum 1 ms or 4 ms) Erase 7. Clear the ERASE bit. 8. Wait for a time, t (minimum 5 μs) NVH 9. Clear the HVEN bit. 10. After a time, t (typical 1 μs), the memory can be accessed in read mode again. RCV NOTE Programming and erasing of FLASH locations cannot be performed by code being executed from FLASH memory. While these operations must be performed in the order shown, other unrelated operations may occur between the steps. In applications that need more than 1000 program/erase cycles, use the 4-ms page erase specification to get improved long-term reliability. Any application can use this 4-ms page erase specification. However, in applications where a FLASH location will be erased and reprogrammed less than 1000 times, and speed is important, use the 1-ms page erase specification to get a shorter cycle time. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 40 Freescale Semiconductor

FLASH Memory (FLASH) 2.6.4 FLASH Mass Erase Operation Use this step-by-step procedure to erase entire FLASH memory to read as logic 1: 1. Set both the ERASE bit, and the MASS bit in the FLASH control register. 2. Read from the FLASH block protect register. 3. Write any data to any FLASH address(1) within the FLASH memory address range. 4. Wait for a time, t (minimum 10 μs) NVS 5. Set the HVEN bit. 6. Wait for a time, t (minimum 4 ms) MErase 7. Clear the ERASE and MASS bits. NOTE Mass erase is disabled whenever any block is protected (FLBPR does not equal $FF). 8. Wait for a time, t (minimum 100 μs) NVHL 9. Clear the HVEN bit. 10. After a time, t (typical 1 μs), the memory can be accessed in read mode again. RCV NOTE Programming and erasing of FLASH locations cannot be performed by code being executed from FLASH memory. While these operations must be performed in the order shown, other unrelated operations may occur between the steps. 2.6.5 FLASH Program/Read Operation Programming of the FLASH memory is done on a row basis. A row consists of 32 consecutive bytes starting from addresses $XX00, $XX20, $XX40, $XX60, $XX80, $XXA0, $XXC0, and $XXE0. During the programming cycle, make sure that all addresses being written to fit within one of the ranges specified above. Attempts to program addresses in different row ranges in one programming cycle will fail. Use this step-by-step procedure to program a row of FLASH memory (Figure 2-4 is a flowchart representation). NOTE Only bytes which are currently $FF may be programmed. 1. Set the PGM bit. This configures the memory for program operation and enables the latching of address and data for programming. 2. Read from the FLASH block protect register. 3. Write any data to any FLASH address within the row address range desired. 4. Wait for a time, t (minimum 10 μs). NVS 5. Set the HVEN bit. 6. Wait for a time, t (minimum 5 μs). PGS 7. Write data to the FLASH address to be programmed. 8. Wait for a time, t (minimum 30 μs). PROG 9. Repeat step 7 and 8 until all the bytes within the row are programmed. 1. When in monitor mode, with security sequence failed (see 20.3.2 Security), write to the FLASH block protect register instead of any FLASH address. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 41

Memory 10. Clear the PGM bit.(1) 11. Wait for a time, t (minimum 5 μs). NVH 12. Clear the HVEN bit. 13. After time, t (typical 1 μs), the memory can be accessed in read mode again. RCV This program sequence is repeated throughout the memory until all data is programmed. NOTE Programming and erasing of FLASH locations can not be performed by code being executed from the same FLASH array. NOTE While these operations must be performed in the order shown, other unrelated operations may occur between the steps. Care must be taken within the FLASH array memory space such as the COP control register (COPCTL) at $FFFF. NOTE It is highly recommended that interrupts be disabled during program/ erase operations. NOTE Do not exceed t maximum or t maximum. t is defined as the PROG HV HV cumulative high voltage programming time to the same row before next erase. t must satisfy this condition: HV t + t + t + (t x 32) ≤ t maximum NVS NVH PGS PROG HV Refer to 21.15 Memory Characteristics. NOTE The time between programming the FLASH address change (step 7 to step 7), or the time between the last FLASH programmed to clearing the PGM bit (step 7 to step 10) must not exceed the maximum programming time, t maximum. PROG CAUTION Be cautious when programming the FLASH array to ensure that non-FLASH locations are not used as the address that is written to when selecting either the desired row address range in step 3 of the algorithm or the byte to be programmed in step 7 of the algorithm. This applies particularly to $FFD4–$FFDF. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 42 Freescale Semiconductor

FLASH Memory (FLASH) Algorithm for programming 1 SET PGM BIT a row (32 bytes) of FLASH memory 2 READ THE FLASH BLOCK PROTECT REGISTER 3 WRITE ANY DATA TO ANY FLASH ADDRESS WITHIN THE ROW ADDRESS RANGE DESIRED 4 WAIT FOR A TIME, t NVS 5 SET HVEN BIT 6 WAIT FOR A TIME, t PGS 7 WRITE DATA TO THE FLASH ADDRESS TO BE PROGRAMMED 8 WAIT FOR A TIME, t PROG COMPLETED Y PROGRAMMING THIS ROW? N 10 CLEAR PGM BIT 11 WAIT FOR A TIME, t NVH Note: 12 The time between each FLASH address change (step 7 to step 7), CLEAR HVEN BIT or the time between the last FLASH address programmed to clearing PGM bit (step 7 to step 10) must not exceed the maximum programming 13 WAIT FOR A TIME, t RCV time, t max. PROG This row program algorithm assumes the row/s to be programmed are initially erased. END OF PROGRAMMING Figure 2-4. FLASH Programming Flowchart MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 43

Memory 2.6.6 FLASH Block Protection Due to the ability of the on-board charge pump to erase and program the FLASH memory in the target application, provision is made for protecting a block of memory from unintentional erase or program operations due to system malfunction. This protection is done by using of a FLASH block protect register (FLBPR). The FLBPR determines the range of the FLASH memory which is to be protected. The range of the protected area starts from a location defined by FLBPR and ends at the bottom of the FLASH memory ($FFFF). When the memory is protected, the HVEN bit cannot be set in either ERASE or PROGRAM operations. NOTE In performing a program or erase operation, the FLASH block protect register must be read after setting the PGM or ERASE bit and before asserting the HVEN bit When the FLBPR is program with all 0’s, the entire memory is protected from being programmed and erased. When all the bits are erased (all 1’s), the entire memory is accessible for program and erase. When bits within the FLBPR are programmed, they lock a block of memory, address ranges as shown in 2.6.7 FLASH Block Protect Register. Once the FLBPR is programmed with a value other than $FF or $FE, any erase or program of the FLBPR or the protected block of FLASH memory is prohibited. Mass erase is disabled whenever any block is protected (FLBPR does not equal $FF). The presence of a V on the TST IRQ pin will bypass the block protection so that all of the memory included in the block protect register is open for program and erase operations. NOTE The FLASH block protect register is not protected with special hardware or software. Therefore, if this page is not protected by FLBPR the register is erased by either a page or mass erase operation. 2.6.7 FLASH Block Protect Register The FLASH block protect register (FLBPR) is implemented as a byte within the FLASH memory, and therefore can only be written during a programming sequence of the FLASH memory. The value in this register determines the starting location of the protected range within the FLASH memory. Address: $FF7E Bit 7 6 5 4 3 2 1 Bit 0 Read: BPR7 BPR6 BPR5 BPR4 BPR3 BPR2 BPR1 BPR0 Write: Reset: U U U U U U U U U = Unaffected by reset. Initial value from factory is 1. Write to this register is by a programming sequence to the FLASH memory. Figure 2-5. FLASH Block Protect Register (FLBPR) BPR[7:0] — FLASH Block Protect Bits These eight bits represent bits [13:6] of a 16-bit memory address. Bit 15 and Bit 14 are 1s and bits [5:0] are 0s. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 44 Freescale Semiconductor

FLASH Memory (FLASH) The resultant 16-bit address is used for specifying the start address of the FLASH memory for block protection. The FLASH is protected from this start address to the end of FLASH memory, at $FFFF. With this mechanism, the protect start address can be $XX00, $XX40, $XX80, and $XXC0 (64 bytes page boundaries) within the FLASH memory. 16-BIT MEMORY ADDRESS START ADDRESS OF FLASH 1 1 FLBPR VALUE 0 0 0 0 0 0 BLOCK PROTECT Figure 2-6. FLASH Block Protect Start Address Table 2-2. Examples of Protect Address Ranges BPR[7:0] Addresses of Protect Range $00 The entire FLASH memory is protected. $01 (0000 0001) $C040 (1100 0000 0100 0000) — $FFFF $02 (0000 0010) $C080 (1100 0000 1000 0000) — $FFFF $03 (0000 0011) $C0C0 (1100 0000 1100 0000) — $FFFF $04 (0000 0100) $C100 (1100 0001 0000 0000) — $FFFF and so on... $FC (1111 1100) $FF00 (1111 1111 0000 0000) — FFFF $FF40 (1111 1111 0100 0000) — $FFFF $FD (1111 1101) FLBPR and vectors are protected $FF80 (1111 1111 1000 0000) — FFFF $FE (1111 1110) Vectors are protected $FF The entire FLASH memory is not protected. 2.6.8 Wait Mode Putting the MCU into wait mode while the FLASH is in read mode does not affect the operation of the FLASH memory directly, but there will not be any memory activity since the CPU is inactive. The WAIT instruction should not be executed while performing a program or erase operation on the FLASH, otherwise the operation will discontinue, and the FLASH will be on standby mode. 2.6.9 Stop Mode Putting the MCU into stop mode while the FLASH is in read mode does not affect the operation of the FLASH memory directly, but there will not be any memory activity since the CPU is inactive. The STOP instruction should not be executed while performing a program or erase operation on the FLASH, otherwise the operation will discontinue, and the FLASH will be on standby mode NOTE Standby mode is the power saving mode of the FLASH module in which all internal control signals to the FLASH are inactive and the current consumption of the FLASH is at a minimum. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 45

Memory MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 46 Freescale Semiconductor

Chapter 3 Analog-to-Digital Converter (ADC) 3.1 Introduction This section describes the 10-bit analog-to-digital converter (ADC). 3.2 Features Features of the ADC module include: (cid:129) Eight channels with multiplexed input (cid:129) Linear successive approximation with monotonicity (cid:129) 10-bit resolution (cid:129) Single or continuous conversion (cid:129) Conversion complete flag or conversion complete interrupt (cid:129) Selectable ADC clock (cid:129) Left or right justified result (cid:129) Left justified sign data mode 3.3 Functional Description The ADC provides eight pins for sampling external sources at pins PTB7/AD7–PTB0/AD0. An analog multiplexer allows the single ADC converter to select one of eight ADC channels as ADC voltage in (V ). V is converted by the successive approximation register-based analog-to-digital converter. ADIN ADIN When the conversion is completed, ADC places the result in the ADC data register and sets a flag or generates an interrupt. See Figure 3-2. 3.3.1 ADC Port I/O Pins PTB7/AD7–PTB0/AD0 are general-purpose I/O (input/output) pins that share with the ADC channels. The channel select bits define which ADC channel/port pin will be used as the input signal. The ADC overrides the port I/O logic by forcing that pin as input to the ADC. The remaining ADC channels/port pins are controlled by the port I/O logic and can be used as general-purpose I/O. Writes to the port register or data direction register (DDR) will not have any affect on the port pin that is selected by the ADC. Read of a port pin in use by the ADC will return a logic 0. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 47

Analog-to-Digital Converter (ADC) INTERNAL BUS M68HC08 CPU REGCISPTUERS ARITUHNMIET T(AICL/ULO)GIC PROGRAMMMOADBULLEE TIMEBASE DDRA PORTA PPTTAA70//KKBBDD70–(1) PTB7/AD7 SINGLE BREAKPOINT CONTROL AND STATUS REGISTERS — 64 BYTES PTB6/AD6 BREAK MODULE PTB5/AD5 USER FLASH — 15,872 BYTES LOWD-UVAOLL TVAOGLETA INGHEIBIT DDRB PORTB PPTTBB43//AADD43 MODULE PTB2/AD2 USER RAM — 1024 BYTES PTB1/AD1 8-BIT KEYBOARD PTB0/AD0 MONITOR ROM — 350 BYTES INTERRUPT MODULE PTC6(1) PTC5(1) FLASH PROGRAMMING ROUTINES ROM — 406 BYTES 2-CHANNEL TIMER USER FLASH VECTOR SPACE — 44 BYTES INTERFACE MODULE 1 DDRC PORTC PPPTTTCCC432(((111))),,, (((222))) 2-CHANNEL TIMER INTERFACE MODULE 2 PTC1/CANRX(1), (2) CLOCK GENERATOR MODULE PTC0/CAN (1), (2) TX OSC1 1–8 MHz OSCILLATOR ENHANCED SERIAL OSC2 COMUNICATIONS PTD7/T2CH1(1) PHASE LOCKED LOOP INTERFACE MODULE PTD6/T2CH0(1) CGMXFC PTD5/T1CH1(1) RST(3) SYSTEM INTEGRATION COPMRPOUPTEERRL YO MPEORDAUTLIENG DDRD PORTD PPPTTTDDD243///MTS1POCSSHCI(0K1()(11)) MODULE SERIAL PERIPHERAL PTD1/MISO(1) INTERFACE MODULE PTD0/SS(1) IRQ(3) SINGLE EXTERNAL INTERRUPT MODULE PTE5–PTE2 VVDDAD//VVREFH 10-CBOITN AVNEARLTOEGR- MTOO-DDUIGLIETAL MONITOR MODULE DDRE PORTE PPTTEE10//RTxxDD DDAD REFL MEMORY MAP MODULE POWER-ON RESET MODULE SECURITY CONFIGURATION MODULE VDD REGISTER 1–2 VSS POWER MODULE V DDA V MONITOR MODE ENTRY SSA MSCAN08 MODULE MODULE 1. Ports are software configurable with pullup device if input port. 2. Higher current drive port pins 3. Pin contains integrated pullup device Figure 3-1. Block Diagram Highlighting ADC Block and Pins MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 48 Freescale Semiconductor

Functional Description INTERNAL DATA BUS READ DDRBx WRITE DDRBx DISABLE DDRBx RESET WRITE PTBx PTBx PTBx ADC CHANNEL x READ PTBx DISABLE ADC DATA REGISTER ADC CONVERSION VOLTAGE IN INTERRUPT COMPLETE (VADIN) CHANNEL ADCH4–ADCH0 ADC LOGIC SELECT AIEN COCO ADC CLOCK CGMXCLK CLOCK BUS CLOCK GENERATOR ADIV2–ADIV0 ADICLK Figure 3-2. ADC Block Diagram 3.3.2 Voltage Conversion When the input voltage to the ADC equals V , the ADC converts the signal to $3FF (full scale). If the REFH input voltage equals V , the ADC converts it to $000. Input voltages between V and V are a REFL REFH REFL straight-line linear conversion. NOTE The ADC input voltage must always be greater than V and less than SSAD V . DDAD Connect the V pin to the same voltage potential as the V pin, and DDAD DD connect the V pin to the same voltage potential as the V pin. SSAD SS The V pin should be routed carefully for maximum noise immunity. DDAD MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 49

Analog-to-Digital Converter (ADC) 3.3.3 Conversion Time Conversion starts after a write to the ADC status and control register (ADSCR). One conversion will take between 16 and 17 ADC clock cycles. The ADIVx and ADICLK bits should be set to provide a 1-MHz ADC clock frequency. 16 to 17 ADC cycles Conversion time = ADC frequency Number of bus cycles = conversion time × bus frequency 3.3.4 Conversion In continuous conversion mode, the ADC data register will be filled with new data after each conversion. Data from the previous conversion will be overwritten whether that data has been read or not. Conversions will continue until the ADCO bit is cleared. The COCO bit is set after each conversion and will stay set until the next read of the ADC data register. In single conversion mode, conversion begins with a write to the ADSCR. Only one conversion occurs between writes to the ADSCR. When a conversion is in process and the ADCSCR is written, the current conversion data should be discarded to prevent an incorrect reading. 3.3.5 Accuracy and Precision The conversion process is monotonic and has no missing codes. 3.3.6 Result Justification The conversion result may be formatted in four different ways: 1. Left justified 2. Right justified 3. Left Justified sign data mode 4. 8-bit truncation mode All four of these modes are controlled using MODE0 and MODE1 bits located in the ADC clock register (ADCLK). Left justification will place the eight most significant bits (MSB) in the corresponding ADC data register high, ADRH. This may be useful if the result is to be treated as an 8-bit result where the two least significant bits (LSB), located in the ADC data register low, ADRL, can be ignored. However, ADRL must be read after ADRH or else the interlocking will prevent all new conversions from being stored. Right justification will place only the two MSBs in the corresponding ADC data register high, ADRH, and the eight LSBs in ADC data register low, ADRL. This mode of operation typically is used when a 10-bit unsigned result is desired. Left justified sign data mode is similar to left justified mode with one exception. The MSB of the 10-bit result, AD9 located in ADRH, is complemented. This mode of operation is useful when a result, represented as a signed magnitude from mid-scale, is needed. Finally, 8-bit truncation mode will place the eight MSBs in the ADC data register low, ADRL. The two LSBs are dropped. This mode of operation MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 50 Freescale Semiconductor

Monotonicity is used when compatibility with 8-bit ADC designs are required. No interlocking between ADRH and ADRL is present. NOTE Quantization error is affected when only the most significant eight bits are used as a result. See Figure 3-3. 8-BIT 10-BIT RESULT RESULT IDEAL 8-BIT CHARACTERISTIC WITH QUANTIZATION = ±1/2 003 10-BIT TRUNCATED TO 8-BIT RESULT 00B 00A IDEAL 10-BIT CHARACTERISTIC 009 WITH QUANTIZATION = ±1/2 002 008 007 006 005 001 004 003 WHEN TRUNCATION IS USED, ERROR FROM IDEAL 8-BIT = 3/8 LSB 002 DUE TO NON-IDEAL QUANTIZATION. 001 000 000 1/2 2 1/2 4 1/2 6 1/2 8 1/2 INPUT VOLTAGE 1 1/2 3 1/2 5 1/2 7 1/2 9 1/2 REPRESENTED AS 10-BIT INPUT VOLTAGE 1/2 1 1/2 2 1/2 REPRESENTED AS 8-BIT Figure 3-3. Bit Truncation Mode Error 3.4 Monotonicity The conversion process is monotonic and has no missing codes. 3.5 Interrupts When the AIEN bit is set, the ADC module is capable of generating CPU interrupts after each ADC conversion. A CPU interrupt is generated if the COCO bit is at logic 0. The COCO bit is not used as a conversion complete flag when interrupts are enabled. 3.6 Low-Power Modes The WAIT and STOP instruction can put the MCU in low power-consumption standby modes. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 51

Analog-to-Digital Converter (ADC) 3.6.1 Wait Mode The ADC continues normal operation during wait mode. Any enabled CPU interrupt request from the ADC can bring the MCU out of wait mode. If the ADC is not required to bring the MCU out of wait mode, power down the ADC by setting ADCH4–ADCH0 bits in the ADC status and control register before executing the WAIT instruction. 3.6.2 Stop Mode The ADC module is inactive after the execution of a STOP instruction. Any pending conversion is aborted. ADC conversions resume when the MCU exits stop mode after an external interrupt. Allow one conversion cycle to stabilize the analog circuitry. 3.7 I/O Signals The ADC module has eight pins shared with port B, PTB7/AD7–PTB0/AD0. 3.7.1 ADC Analog Power Pin (V ) DDAD The ADC analog portion uses V as its power pin. Connect the V pin to the same voltage DDAD DDAD potential as V . External filtering may be necessary to ensure clean V for good results. DD DDAD NOTE For maximum noise immunity, route V carefully and place bypass DDAD capacitors as close as possible to the package. V and V are double-bonded on the MC68HC908GZ16. DDAD REFH 3.7.2 ADC Analog Ground Pin (V ) SSAD The ADC analog portion uses V as its ground pin. Connect the V pin to the same voltage SSAD SSAD potential as V . SS NOTE Route V cleanly to avoid any offset errors. SSAD V and V are double-bonded on the MC68HC908GZ16. SSAD REFL 3.7.3 ADC Voltage Reference High Pin (V ) REFH The ADC analog portion uses V as its upper voltage reference pin. By default, connect the V REFH REFH pin to the same voltage potential as V . External filtering is often necessary to ensure a clean V for DD REFH good results. Any noise present on this pin will be reflected and possibly magnified in A/D conversion values. NOTE For maximum noise immunity, route V carefully and place bypass REFH capacitors as close as possible to the package. Routing V close and REFH parallel to V may improve common mode noise rejection. REFL V and V are double-bonded on the MC68HC908GZ16. DDAD REFH MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 52 Freescale Semiconductor

I/O Registers 3.7.4 ADC Voltage Reference Low Pin (V ) REFL The ADC analog portion uses V as its lower voltage reference pin. By default, connect the V pin REFL REFH to the same voltage potential as V . External filtering is often necessary to ensure a clean V for good SS REFL results. Any noise present on this pin will be reflected and possibly magnified in A/D conversion values. NOTE For maximum noise immunity, route V carefully and, if not connected REFL to V , place bypass capacitors as close as possible to the package. SS Routing V close and parallel to V may improve common mode REFH REFL noise rejection. V and V are double-bonded on the MC68HC908GZ16. SSAD REFL 3.7.5 ADC Voltage In (V ) ADIN V is the input voltage signal from one of the eight ADC channels to the ADC module. ADIN 3.8 I/O Registers These I/O registers control and monitor ADC operation: (cid:129) ADC status and control register (ADSCR) (cid:129) ADC data register (ADRH and ADRL) (cid:129) ADC clock register (ADCLK) 3.8.1 ADC Status and Control Register Function of the ADC status and control register (ADSCR) is described here. Address: $003C Bit 7 6 5 4 3 2 1 Bit 0 Read: COCO AIEN ADCO ADCH4 ADCH3 ADCH2 ADCH1 ADCH0 Write: Reset: 0 0 0 1 1 1 1 1 Figure 3-4. ADC Status and Control Register (ADSCR) COCO — Conversions Complete Bit In non-interrupt mode (AIEN = 0), COCO is a read-only bit that is set at the end of each conversion. COCO will stay set until cleared by a read of the ADC data register. Reset clears this bit. In interrupt mode (AIEN = 1), COCO is a read-only bit that is not set at the end of a conversion. It always reads as a logic 0. 1 = Conversion completed (AIEN = 0) 0 = Conversion not completed (AIEN = 0) or CPU interrupt enabled (AIEN = 1) AIEN — ADC Interrupt Enable Bit When this bit is set, an interrupt is generated at the end of an ADC conversion. The interrupt signal is cleared when the data register is read or the status/control register is written. Reset clears the AIEN bit. 1 = ADC interrupt enabled 0 = ADC interrupt disabled MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 53

Analog-to-Digital Converter (ADC) ADCO — ADC Continuous Conversion Bit When set, the ADC will convert samples continuously and update the ADR register at the end of each conversion. Only one conversion is completed between writes to the ADSCR when this bit is cleared. Reset clears the ADCO bit. 1 = Continuous ADC conversion 0 = One ADC conversion ADCH4–ADCH0 — ADC Channel Select Bits ADCH4–ADCH0 form a 5-bit field which is used to select one of 16 ADC channels. Only eight channels, AD7–AD0, are available on this MCU. The channels are detailed in Table 3-1. Care should be taken when using a port pin as both an analog and digital input simultaneously to prevent switching noise from corrupting the analog signal. See Table 3-1. The ADC subsystem is turned off when the channel select bits are all set to 1. This feature allows for reduced power consumption for the MCU when the ADC is not being used. NOTE Recovery from the disabled state requires one conversion cycle to stabilize. The voltage levels supplied from internal reference nodes, as specified in Table 3-1, are used to verify the operation of the ADC converter both in production test and for user applications. Table 3-1. Mux Channel Select(1) ADCH4 ADCH3 ADCH2 ADCH1 ADCH0 Input Select 0 0 0 0 0 PTB0/AD0 0 0 0 0 1 PTB1/AD1 0 0 0 1 0 PTB2/AD2 0 0 0 1 1 PTB3/AD3 0 0 1 0 0 PTB4/AD4 0 0 1 0 1 PTB5/AD5 0 0 1 1 0 PTB6/AD6 0 0 1 1 1 PTB7/AD7 0 1 0 0 0 ↓ ↓ ↓ ↓ ↓ Unused 1 1 1 0 0 1 1 1 0 1 VREFH 1 1 1 1 0 VREFL 1 1 1 1 1 ADC power off 1. If any unused channels are selected, the resulting ADC conversion will be unknown or reserved. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 54 Freescale Semiconductor

I/O Registers 3.8.2 ADC Data Register High and Data Register Low 3.8.2.1 Left Justified Mode In left justified mode, the ADRH register holds the eight MSBs of the 10-bit result. The only difference from left justified mode is that the AD9 is complemented. The ADRL register holds the two LSBs of the 10-bit result. All other bits read as 0. ADRH and ADRL are updated each time an ADC single channel conversion completes. Reading ADRH latches the contents of ADRL until ADRL is read. All subsequent results will be lost until the ADRH and ADRL reads are completed. Address: $003D ADRH Bit 7 6 5 4 3 2 1 Bit 0 Read: AD9 AD8 AD7 AD6 AD5 AD4 AD3 AD2 Write: Reset: Unaffected by reset Address: $003E ADRL Read: AD1 AD0 0 0 0 0 0 0 Write: Reset: Unaffected by reset =Unimplemented Figure 3-5. ADC Data Register High (ADRH) and Low (ADRL) 3.8.2.2 Right Justified Mode In right justified mode, the ADRH register holds the two MSBs of the 10-bit result. All other bits read as 0. The ADRL register holds the eight LSBs of the 10-bit result. ADRH and ADRL are updated each time an ADC single channel conversion completes. Reading ADRH latches the contents of ADRL until ADRL is read. All subsequent results will be lost until the ADRH and ADRL reads are completed. Address: $003D ADRH Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 0 0 AD9 AD8 Write: Reset: Unaffected by reset Address: $003E ADRL Read: AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0 Write: Reset: Unaffected by reset =Unimplemented Figure 3-6. ADC Data Register High (ADRH) and Low (ADRL) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 55

Analog-to-Digital Converter (ADC) 3.8.2.3 Left Justified Signed Data Mode In left justified signed data mode, the ADRH register holds the eight MSBs of the 10-bit result. The only difference from left justified mode is that the AD9 is complemented. The ADRL register holds the two LSBs of the 10-bit result. All other bits read as 0. ADRH and ADRL are updated each time an ADC single channel conversion completes. Reading ADRH latches the contents of ADRL until ADRL is read. All subsequent results will be lost until the ADRH and ADRL reads are completed. Address: $003D Bit 7 6 5 4 3 2 1 Bit 0 Read: AD9 AD8 AD7 AD6 AD5 AD4 AD3 AD2 Write: Reset: Unaffected by reset Address: $003E Read: AD1 AD0 0 0 0 0 0 0 Write: Reset: Unaffected by reset =Unimplemented Figure 3-7. ADC Data Register High (ADRH) and Low (ADRL) 3.8.2.4 Eight Bit Truncation Mode In 8-bit truncation mode, the ADRL register holds the eight MSBs of the 10-bit result. The ADRH register is unused and reads as 0. The ADRL register is updated each time an ADC single channel conversion completes. In 8-bit mode, the ADRL register contains no interlocking with ADRH. Address: $003D ADRH Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 0 0 0 0 Write: Reset: Unaffected by reset Address: $003E ADRL Read: AD9 AD8 AD7 AD6 AD5 AD4 AD3 AD2 Write: Reset: Unaffected by reset =Unimplemented Figure 3-8. ADC Data Register High (ADRH) and Low (ADRL) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 56 Freescale Semiconductor

I/O Registers 3.8.3 ADC Clock Register The ADC clock register (ADCLK) selects the clock frequency for the ADC. Address: $003F Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 ADIV2 ADIV1 ADIV0 ADICLK MODE1 MODE0 R Write: Reset: 0 0 0 0 0 1 0 0 =Unimplemented R =Reserved Figure 3-9. ADC Clock Register (ADCLK) ADIV2–ADIV0 — ADC Clock Prescaler Bits ADIV2–ADIV0 form a 3-bit field which selects the divide ratio used by the ADC to generate the internal ADC clock. Table 3-2 shows the available clock configurations. The ADC clock should be set to approximately 1 MHz. Table 3-2. ADC Clock Divide Ratio ADIV2 ADIV1 ADIV0 ADC Clock Rate 0 0 0 ADC input clock ÷ 1 0 0 1 ADC input clock ÷ 2 0 1 0 ADC input clock ÷ 4 0 1 1 ADC input clock ÷ 8 1 X(1) X(1) ADC input clock ÷ 16 1. X = Don’t care ADICLK — ADC Input Clock Select Bit ADICLK selects either the bus clock or the oscillator output clock (CGMXCLK) as the input clock source to generate the internal ADC clock. Reset selects CGMXCLK as the ADC clock source. 1 = Internal bus clock 0 = Oscillator output clock (CGMXCLK) The ADC requires a clock rate of approximately 1 MHz for correct operation. If the selected clock source is not fast enough, the ADC will generate incorrect conversions. See 21.10 5.0-Volt ADC Characteristics. f or bus frequency CGMXCLK f = ≅ 1 MHz ADIC ADIV[2:0] MODE1 and MODE0 — Modes of Result Justification Bits MODE1 and MODE0 select among four modes of operation. The manner in which the ADC conversion results will be placed in the ADC data registers is controlled by these modes of operation. Reset returns right-justified mode. 00 = 8-bit truncation mode 01 = Right justified mode 10 = Left justified mode 11 = Left justified signed data mode MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 57

Analog-to-Digital Converter (ADC) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 58 Freescale Semiconductor

Chapter 4 Clock Generator Module (CGM) 4.1 Introduction This section describes the clock generator module. The CGM generates the crystal clock signal, CGMXCLK, which operates at the frequency of the crystal. The CGM also generates the base clock signal, CGMOUT, which is based on either the crystal clock divided by two or the phase-locked loop (PLL) clock, CGMVCLK, divided by two. In user mode, CGMOUT is the clock from which the SIM derives the system clocks, including the bus clock, which is at a frequency of CGMOUT/2. The PLL is a fully functional frequency generator designed for use with crystals or ceramic resonators. The PLL can generate a maximum bus frequency of 8 MHz using a 1-8MHz crystal or external clock source. 4.2 Features Features of the CGM include: (cid:129) Phase-locked loop with output frequency in integer multiples of an integer dividend of the crystal reference (cid:129) High-frequency crystal operation with low-power operation and high-output frequency resolution (cid:129) Programmable hardware voltage-controlled oscillator (VCO) for low-jitter operation (cid:129) Automatic bandwidth control mode for low-jitter operation (cid:129) Automatic frequency lock detector (cid:129) CPU interrupt on entry or exit from locked condition (cid:129) Configuration register bit to allow oscillator operation during stop mode 4.3 Functional Description The CGM consists of three major submodules: (cid:129) Crystal oscillator circuit — The crystal oscillator circuit generates the constant crystal frequency clock, CGMXCLK. (cid:129) Phase-locked loop (PLL) — The PLL generates the programmable VCO frequency clock, CGMVCLK. (cid:129) Base clock selector circuit — This software-controlled circuit selects either CGMXCLK divided by two or the VCO clock, CGMVCLK, divided by two as the base clock, CGMOUT. The SIM derives the system clocks from either CGMOUT or CGMXCLK. Figure 4-1 shows the structure of the CGM. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 59

Clock Generator Module (CGM) OSCILLATOR (OSC) OSC2 CGMXCLK (TO: SIM, TIMTB15A, ADC) OSC1 SIMOSCEN (FROM SIM) OSCSTOPENB (FROM CONFIG) PHASE-LOCKED LOOP (PLL) CGMRCLK A CGMOUT CLOCK BCS SELECT ÷ 2 B S* (TO SIM) CIRCUIT *WHEN S = 1, SIMDIV2 VDDA CGMXFC VSSA CGMOUT = B (FROM SIM) VPR1–VPR0 VRS7–VRS0 VOLTAGE PHASE LOOP DETECTOR FILTER CONTROLLED CGMVCLK OSCILLATOR PLL ANALOG AUTOMATIC CGMINT LOCK INTERRUPT MODE DETECTOR CONTROL CONTROL (TO SIM) LOCK AUTO ACQ PLLIE PLLF MUL11–MUL0 CGMVDV FREQUENCY DIVIDER Figure 4-1. CGM Block Diagram MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 60 Freescale Semiconductor

Functional Description 4.3.1 Crystal Oscillator Circuit The crystal oscillator circuit consists of an inverting amplifier and an external crystal. The OSC1 pin is the input to the amplifier and the OSC2 pin is the output. The SIMOSCEN signal from the system integration module (SIM) or the OSCSTOPENB bit in the CONFIG register enable the crystal oscillator circuit. The CGMXCLK signal is the output of the crystal oscillator circuit and runs at a rate equal to the crystal frequency. CGMXCLK is then buffered to produce CGMRCLK, the PLL reference clock. CGMXCLK can be used by other modules which require precise timing for operation. The duty cycle of CGMXCLK is not guaranteed to be 50% and depends on external factors, including the crystal and related external components. An externally generated clock also can feed the OSC1 pin of the crystal oscillator circuit. Connect the external clock to the OSC1 pin and let the OSC2 pin float. 4.3.2 Phase-Locked Loop Circuit (PLL) The PLL is a frequency generator that can operate in either acquisition mode or tracking mode, depending on the accuracy of the output frequency. The PLL can change between acquisition and tracking modes either automatically or manually. 4.3.3 PLL Circuits The PLL consists of these circuits: (cid:129) Voltage-controlled oscillator (VCO) (cid:129) Modulo VCO frequency divider (cid:129) Phase detector (cid:129) Loop filter (cid:129) Lock detector The operating range of the VCO is programmable for a wide range of frequencies and for maximum immunity to external noise, including supply and CGMXFC noise. The VCO frequency is bound to a range from roughly one-half to twice the center-of-range frequency, f . Modulating the voltage on the VRS CGMXFC pin changes the frequency within this range. By design, f is equal to the nominal VRS center-of-range frequency, f , (71.4 kHz) times a linear factor, L, and a power-of-two factor, E, or NOM (L×2E)f . NOM CGMRCLK is the PLL reference clock, a buffered version of CGMXCLK. CGMRCLK runs at a frequency, f . The VCO’s output clock, CGMVCLK, running at a frequency, f , is fed back through a RCLK VCLK programmable modulo divider. The modulo divider reduces the VCO clock by a factor, N. The dividers output is the VCO feedback clock, CGMVDV, running at a frequency, f = f /(N). For more VDV VCLK information, see 4.3.6 Programming the PLL. The phase detector then compares the VCO feedback clock, CGMVDV, with the final reference clock, CGMRDV. A correction pulse is generated based on the phase difference between the two signals. The loop filter then slightly alters the DC voltage on the external capacitor connected to CGMXFC based on the width and direction of the correction pulse. The filter can make fast or slow corrections depending on its mode, described in 4.3.4 Acquisition and Tracking Modes. The value of the external capacitor and the reference frequency determines the speed of the corrections and the stability of the PLL. The lock detector compares the frequencies of the VCO feedback clock, CGMVDV, and the reference clock, CGMRCLK. Therefore, the speed of the lock detector is directly proportional to the reference MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 61

Clock Generator Module (CGM) frequency, f . The circuit determines the mode of the PLL and the lock condition based on this RCLK comparison. 4.3.4 Acquisition and Tracking Modes The PLL filter is manually or automatically configurable into one of two operating modes: (cid:129) Acquisition mode — In acquisition mode, the filter can make large frequency corrections to the VCO. This mode is used at PLL start up or when the PLL has suffered a severe noise hit and the VCO frequency is far off the desired frequency. When in acquisition mode, the ACQ bit is clear in the PLL bandwidth control register. (See 4.5.2 PLL Bandwidth Control Register.) (cid:129) Tracking mode — In tracking mode, the filter makes only small corrections to the frequency of the VCO. PLL jitter is much lower in tracking mode, but the response to noise is also slower. The PLL enters tracking mode when the VCO frequency is nearly correct, such as when the PLL is selected as the base clock source. (See 4.3.8 Base Clock Selector Circuit.) The PLL is automatically in tracking mode when not in acquisition mode or when the ACQ bit is set. 4.3.5 Manual and Automatic PLL Bandwidth Modes The PLL can change the bandwidth or operational mode of the loop filter manually or automatically. Automatic mode is recommended for most users. In automatic bandwidth control mode (AUTO = 1), the lock detector automatically switches between acquisition and tracking modes. Automatic bandwidth control mode also is used to determine when the VCO clock, CGMVCLK, is safe to use as the source for the base clock, CGMOUT. (See 4.5.2 PLL Bandwidth Control Register.) If PLL interrupts are enabled, the software can wait for a PLL interrupt request and then check the LOCK bit. If interrupts are disabled, software can poll the LOCK bit continuously (for example, during PLL start up) or at periodic intervals. In either case, when the LOCK bit is set, the VCO clock is safe to use as the source for the base clock. (See 4.3.8 Base Clock Selector Circuit.) If the VCO is selected as the source for the base clock and the LOCK bit is clear, the PLL has suffered a severe noise hit and the software must take appropriate action, depending on the application. (See 4.6 Interrupts for information and precautions on using interrupts.) The following conditions apply when the PLL is in automatic bandwidth control mode: (cid:129) The ACQ bit (See 4.5.2 PLL Bandwidth Control Register.) is a read-only indicator of the mode of the filter. (See 4.3.4 Acquisition and Tracking Modes.) (cid:129) The ACQ bit is set when the VCO frequency is within a certain tolerance and is cleared when the VCO frequency is out of a certain tolerance. (See 4.8 Acquisition/Lock Time Specifications for more information.) (cid:129) The LOCK bit is a read-only indicator of the locked state of the PLL. (cid:129) The LOCK bit is set when the VCO frequency is within a certain tolerance and is cleared when the VCO frequency is out of a certain tolerance. (See 4.8 Acquisition/Lock Time Specifications for more information.) (cid:129) CPU interrupts can occur if enabled (PLLIE = 1) when the PLL’s lock condition changes, toggling the LOCK bit. (See 4.5.1 PLL Control Register.) The PLL also may operate in manual mode (AUTO = 0). Manual mode is used by systems that do not require an indicator of the lock condition for proper operation. Such systems typically operate well below f . BUSMAX MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 62 Freescale Semiconductor

Functional Description The following conditions apply when in manual mode: (cid:129) ACQ is a writable control bit that controls the mode of the filter. Before turning on the PLL in manual mode, the ACQ bit must be clear. (cid:129) Before entering tracking mode (ACQ = 1), software must wait a given time, t (See 4.8 ACQ Acquisition/Lock Time Specifications.), after turning on the PLL by setting PLLON in the PLL control register (PCTL). (cid:129) Software must wait a given time, t , after entering tracking mode before selecting the PLL as the AL clock source to CGMOUT (BCS = 1). (cid:129) The LOCK bit is disabled. (cid:129) CPU interrupts from the CGM are disabled. 4.3.6 Programming the PLL Use the following procedure to program the PLL. For reference, the variables used and their meaning are shown in Table 4-1. Table 4-1. Variable Definitions Variable Definition fBUSDES Desired bus clock frequency fVCLKDES Desired VCO clock frequency fRCLK Chosen reference crystal frequency fVCLK Calculated VCO clock frequency fBUS Calculated bus clock frequency fNOM Nominal VCO center frequency fVRS Programmed VCO center frequency NOTE The round function in the following equations means that the real number should be rounded to the nearest integer number. 1. Choose the desired bus frequency, f . BUSDES 2. Calculate the desired VCO frequency (four times the desired bus frequency). f = 4 x f VCLKDES BUSDES 3. Choose a practical PLL (crystal) reference frequency, f . Typically, the reference crystal is 1–8 RCLK MHz. Frequency errors to the PLL are corrected at a rate of f . RCLK For stability and lock time reduction, this rate must be as fast as possible. The VCO frequency must be an integer multiple of this rate. The relationship between the VCO frequency, f , and the VCLK reference frequency, f ,is: RCLK f = (N) (f ) VCLK RCLK N, the range multiplier, must be an integer. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 63

Clock Generator Module (CGM) In cases where desired bus frequency has some tolerance, choose f to a value determined RCLK either by other module requirements (such as modules which are clocked by CGMXCLK), cost requirements, or ideally, as high as the specified range allows. See Chapter 21 Electrical Specifications. After choosing N, the actual bus frequency can be determined using equation in 2 above. 4. Select a VCO frequency multiplier, N. ⎛f ⎞ VCLKDES N = round⎜--------------------------⎟ f ⎝ RCLK ⎠ 5. Calculate and verify the adequacy of the VCO and bus frequencies f and f . VCLK BUS f = (N)×f VCLK RCLK f = (f )⁄4 BUS VCLK 6. Select the VCO’s power-of-two range multiplier E, according to Table 4-2. Table 4-2. Power-of-Two Range Selectors Frequency Range E 0 < fVCLK ≤ 8 MHz 0 8 MHz< fVCLK ≤ 16 MHz 1 16 MHz< fVCLK ≤ 32 MHz 2(1) 1. Do not program E to a value of 3. 7. Select a VCO linear range multiplier, L, where f = 71.4 kHz NOM f VCLK L = Round 2E x f NOM 8. Calculate and verify the adequacy of the VCO programmed center-of-range frequency, f . The VRS center-of-range frequency is the midpoint between the minimum and maximum frequencies attainable by the PLL. f = (L x 2E) f VRS NOM 9. For proper operation, E f ×2 NOM f –f ≤--------------------------- VRS VCLK 2 10. Verify the choice of N, E, and L by comparing f to f and f . For proper operation, VCLK VRS VCLKDES f must be within the application’s tolerance of f , and f must be as close as possible VCLK VCLKDES VRS to f . VCLK NOTE Exceeding the recommended maximum bus frequency or VCO frequency can crash the MCU. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 64 Freescale Semiconductor

Functional Description 11. Program the PLL registers accordingly: a. In the VPR bits of the PLL control register (PCTL), program the binary equivalent of E. b. In the PLL multiplier select register low (PMSL) and the PLL multiplier select register high (PMSH), program the binary equivalent of N. If using a 1–8 MHz reference, the PMSL register must be reprogrammed from the reset value before enabling the pll. c. In the PLL VCO range select register (PMRS), program the binary coded equivalent of L. Table 4-3 provides numeric examples (register values are in hexadecimal notation): Table 4-3. Numeric Example fBUS fRCLK N E L 500 kHz 1 MHz 002 0 1B 1.25 MHz 1 MHz 005 0 45 2.0 MHz 1 MHz 008 0 70 2.5 MHz 1 MHz 00A 1 45 3.0 MHz 1 MHz 00C 1 53 4.0 MHz 1 MHz 010 1 70 5.0 MHz 1 MHz 014 2 46 7.0 MHz 1 MHz 01C 2 62 8.0 MHz 1 MHz 020 2 70 4.3.7 Special Programming Exceptions The programming method described in 4.3.6 Programming the PLL does not account for two possible exceptions. A value of 0 for N or L is meaningless when used in the equations given. To account for these exceptions: (cid:129) A 0 value for N is interpreted exactly the same as a value of 1. (cid:129) A 0 value for L disables the PLL and prevents its selection as the source for the base clock. See 4.3.8 Base Clock Selector Circuit. 4.3.8 Base Clock Selector Circuit This circuit is used to select either the crystal clock, CGMXCLK, or the VCO clock, CGMVCLK, as the source of the base clock, CGMOUT. The two input clocks go through a transition control circuit that waits up to three CGMXCLK cycles and three CGMVCLK cycles to change from one clock source to the other. During this time, CGMOUT is held in stasis. The output of the transition control circuit is then divided by two to correct the duty cycle. Therefore, the bus clock frequency, which is one-half of the base clock frequency, is one-fourth the frequency of the selected clock (CGMXCLK or CGMVCLK). The BCS bit in the PLL control register (PCTL) selects which clock drives CGMOUT. The VCO clock cannot be selected as the base clock source if the PLL is not turned on. The PLL cannot be turned off if the VCO clock is selected. The PLL cannot be turned on or off simultaneously with the selection or deselection of the VCO clock. The VCO clock also cannot be selected as the base clock source if the factor L is programmed to a 0. This value would set up a condition inconsistent with the operation of the PLL, so that the PLL would be disabled and the crystal clock would be forced as the source of the base clock. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 65

Clock Generator Module (CGM) 4.3.9 CGM External Connections In its typical configuration, the CGM requires external components. Five of these are for the crystal oscillator and two or four are for the PLL. The crystal oscillator is normally connected in a Pierce oscillator configuration, as shown in Figure 4-2. Figure 4-2 shows only the logical representation of the internal components and may not represent actual circuitry. The oscillator configuration uses five components: (cid:129) Crystal, X 1 (cid:129) Fixed capacitor, C 1 (cid:129) Tuning capacitor, C (can also be a fixed capacitor) 2 (cid:129) Feedback resistor, R B (cid:129) Series resistor, R S The series resistor (R ) is included in the diagram to follow strict Pierce oscillator guidelines. Refer to the S crystal manufacturer’s data for more information regarding values for C1 and C2. Figure 4-2 also shows the external components for the PLL: (cid:129) Bypass capacitor, C BYP (cid:129) Filter network Routing should be done with great care to minimize signal cross talk and noise. SIMOSCEN OSCSTOPENB (FROM CONFIG) CGMXCLK OSC1 OSC2 CGMXFC VSSA VDDA V DD RB R F1 C CBYP RS F2 0.1 μF C F1 X1 3 Component Filter C C 1 2 Note: Filter network in box can be replaced with a single capacitor, but will degrade stability. Figure 4-2. CGM External Connections MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 66 Freescale Semiconductor

I/O Signals 4.4 I/O Signals The following paragraphs describe the CGM I/O signals. 4.4.1 Crystal Amplifier Input Pin (OSC1) The OSC1 pin is an input to the crystal oscillator amplifier. 4.4.2 Crystal Amplifier Output Pin (OSC2) The OSC2 pin is the output of the crystal oscillator inverting amplifier. 4.4.3 External Filter Capacitor Pin (CGMXFC) The CGMXFC pin is required by the loop filter to filter out phase corrections. An external filter network is connected to this pin. (See Figure 4-2.) NOTE To prevent noise problems, the filter network should be placed as close to the CGMXFC pin as possible, with minimum routing distances and no routing of other signals across the network. 4.4.4 PLL Analog Power Pin (V ) DDA V is a power pin used by the analog portions of the PLL. Connect the V pin to the same voltage DDA DDA potential as the V pin. DD NOTE Route V carefully for maximum noise immunity and place bypass DDA capacitors as close as possible to the package. 4.4.5 PLL Analog Ground Pin (V ) SSA V is a ground pin used by the analog portions of the PLL. Connect the V pin to the same voltage SSA SSA potential as the V pin. SS NOTE Route V carefully for maximum noise immunity and place bypass SSA capacitors as close as possible to the package. 4.4.6 Oscillator Enable Signal (SIMOSCEN) The SIMOSCEN signal comes from the system integration module (SIM) and enables the oscillator and PLL. 4.4.7 Oscillator Stop Mode Enable Bit (OSCSTOPENB) OSCSTOPENB is a bit in the CONFIG register that enables the oscillator to continue operating during stop mode. If this bit is set, the Oscillator continues running during stop mode. If this bit is not set (default), the oscillator is controlled by the SIMOSCEN signal which will disable the oscillator during stop mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 67

Clock Generator Module (CGM) 4.4.8 Crystal Output Frequency Signal (CGMXCLK) CGMXCLK is the crystal oscillator output signal. It runs at the full speed of the crystal (f ) and comes XCLK directly from the crystal oscillator circuit. Figure 4-2 shows only the logical relation of CGMXCLK to OSC1 and OSC2 and may not represent the actual circuitry. The duty cycle of CGMXCLK is unknown and may depend on the crystal and other external factors. Also, the frequency and amplitude of CGMXCLK can be unstable at start up. 4.4.9 CGM Base Clock Output (CGMOUT) CGMOUT is the clock output of the CGM. This signal goes to the SIM, which generates the MCU clocks. CGMOUT is a 50 percent duty cycle clock running at twice the bus frequency. CGMOUT is software programmable to be either the oscillator output, CGMXCLK, divided by two or the VCO clock, CGMVCLK, divided by two. 4.4.10 CGM CPU Interrupt (CGMINT) CGMINT is the interrupt signal generated by the PLL lock detector. 4.5 CGM Registers These registers control and monitor operation of the CGM: (cid:129) PLL control register (PCTL) (See 4.5.1 PLL Control Register.) (cid:129) PLL bandwidth control register (PBWC) (See 4.5.2 PLL Bandwidth Control Register.) (cid:129) PLL multiplier select register high (PMSH) (See 4.5.3 PLL Multiplier Select Register High.) (cid:129) PLL multiplier select register low (PMSL) (See 4.5.4 PLL Multiplier Select Register Low.) (cid:129) PLL VCO range select register (PMRS) (See 4.5.5 PLL VCO Range Select Register.) Figure 4-3 is a summary of the CGM registers. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 68 Freescale Semiconductor

CGM Registers Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: PLLF PLL Control Register PLLIE PLLON BCS R R VPR1 VPR0 $0036 (PCTL) Write: See page 69. Reset: 0 0 1 0 0 0 0 0 Read: LOCK 0 0 0 0 PLL Bandwidth Control AUTO ACQ R $0037 Register (PBWC) Write: See page 71. Reset: 0 0 0 0 0 0 0 0 Read: 0 0 0 0 PLL Multiplier Select High MUL11 MUL10 MUL9 MUL8 $0038 Register (PMSH) Write: See page 72. Reset: 0 0 0 0 0 0 0 0 Read: PLL Multiplier Select Low MUL7 MUL6 MUL5 MUL4 MUL3 MUL2 MUL1 MUL0 $0039 Register (PMSL) Write: See page 73. Reset: 0 1 0 0 0 0 0 0 Read: PLL VCO Select Range VRS7 VRS6 VRS5 VRS4 VRS3 VRS2 VRS1 VRS0 $003A Register (PMRS) Write: See page 73. Reset: 0 1 0 0 0 0 0 0 Read: 0 0 0 0 R R R R $003B Reserved Register Write: Reset: 0 0 0 0 0 0 0 1 = Unimplemented R = Reserved NOTES: 1. When AUTO = 0, PLLIE is forced clear and is read-only. 2. When AUTO = 0, PLLF and LOCK read as clear. 3. When AUTO = 1, ACQ is read-only. 4. When PLLON = 0 or VRS7:VRS0 = $0, BCS is forced clear and is read-only. 5. When PLLON = 1, the PLL programming register is read-only. 6. When BCS = 1, PLLON is forced set and is read-only. Figure 4-3. CGM I/O Register Summary 4.5.1 PLL Control Register The PLL control register (PCTL) contains the interrupt enable and flag bits, the on/off switch, the base clock selector bit, and the VCO power-of-two range selector bits. Address: $0036 Bit 7 6 5 4 3 2 1 Bit 0 Read: PLLF PLLIE PLLON BCS R R VPR1 VPR0 Write: Reset: 0 0 1 0 0 0 0 0 =Unimplemented R = Reserved Figure 4-4. PLL Control Register (PCTL) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 69

Clock Generator Module (CGM) PLLIE — PLL Interrupt Enable Bit This read/write bit enables the PLL to generate an interrupt request when the LOCK bit toggles, setting the PLL flag, PLLF. When the AUTO bit in the PLL bandwidth control register (PBWC) is clear, PLLIE cannot be written and reads as logic 0. Reset clears the PLLIE bit. 1 = PLL interrupts enabled 0 = PLL interrupts disabled PLLF — PLL Interrupt Flag Bit This read-only bit is set whenever the LOCK bit toggles. PLLF generates an interrupt request if the PLLIE bit also is set. PLLF always reads as logic 0 when the AUTO bit in the PLL bandwidth control register (PBWC) is clear. Clear the PLLF bit by reading the PLL control register. Reset clears the PLLF bit. 1 = Change in lock condition 0 = No change in lock condition NOTE Do not inadvertently clear the PLLF bit. Any read or read-modify-write operation on the PLL control register clears the PLLF bit. PLLON — PLL On Bit This read/write bit activates the PLL and enables the VCO clock, CGMVCLK. PLLON cannot be cleared if the VCO clock is driving the base clock, CGMOUT (BCS = 1). (See 4.3.8 Base Clock Selector Circuit.) Reset sets this bit so that the loop can stabilize as the MCU is powering up. 1 = PLL on 0 = PLL off BCS — Base Clock Select Bit This read/write bit selects either the crystal oscillator output, CGMXCLK, or the VCO clock, CGMVCLK, as the source of the CGM output, CGMOUT. CGMOUT frequency is one-half the frequency of the selected clock. BCS cannot be set while the PLLON bit is clear. After toggling BCS, it may take up to three CGMXCLK and three CGMVCLK cycles to complete the transition from one source clock to the other. During the transition, CGMOUT is held in stasis. (See 4.3.8 Base Clock Selector Circuit.) Reset clears the BCS bit. 1 = CGMVCLK divided by two drives CGMOUT 0 = CGMXCLK divided by two drives CGMOUT NOTE PLLON and BCS have built-in protection that prevents the base clock selector circuit from selecting the VCO clock as the source of the base clock if the PLL is off. Therefore, PLLON cannot be cleared when BCS is set, and BCS cannot be set when PLLON is clear. If the PLL is off (PLLON = 0), selecting CGMVCLK requires two writes to the PLL control register. (See 4.3.8 Base Clock Selector Circuit.). MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 70 Freescale Semiconductor

CGM Registers VPR1 and VPR0 — VCO Power-of-Two Range Select Bits These read/write bits control the VCO’s hardware power-of-two range multiplier E that, in conjunction with L controls the hardware center-of-range frequency, f . VPR1:VPR0 cannot be written when the VRS PLLON bit is set. Reset clears these bits. (See 4.3.3 PLL Circuits, 4.3.6 Programming the PLL, and 4.5.5 PLL VCO Range Select Register.) Table 4-4. VPR1 and VPR0 Programming VCO Power-of-Two VPR1 and VPR0 E Range Multiplier 00 0 1 01 1 2 10 2(1) 4 1. Do not program E to a value of 3. NOTE Verify that the value of the VPR1 and VPR0 bits in the PCTL register are appropriate for the given reference and VCO clock frequencies before enabling the PLL. See 4.3.6 Programming the PLL for detailed instructions on selecting the proper value for these control bits. 4.5.2 PLL Bandwidth Control Register The PLL bandwidth control register (PBWC): (cid:129) Selects automatic or manual (software-controlled) bandwidth control mode (cid:129) Indicates when the PLL is locked (cid:129) In automatic bandwidth control mode, indicates when the PLL is in acquisition or tracking mode (cid:129) In manual operation, forces the PLL into acquisition or tracking mode Address: $0037 Bit 7 6 5 4 3 2 1 Bit 0 Read: LOCK 0 0 0 0 AUTO ACQ R Write: Reset: 0 0 0 0 0 0 0 0 =Unimplemented R = Reserved Figure 4-5. PLL Bandwidth Control Register (PBWC) AUTO — Automatic Bandwidth Control Bit This read/write bit selects automatic or manual bandwidth control. When initializing the PLL for manual operation (AUTO = 0), clear the ACQ bit before turning on the PLL. Reset clears the AUTO bit. 1 = Automatic bandwidth control 0 = Manual bandwidth control MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 71

Clock Generator Module (CGM) LOCK — Lock Indicator Bit When the AUTO bit is set, LOCK is a read-only bit that becomes set when the VCO clock, CGMVCLK, is locked (running at the programmed frequency). When the AUTO bit is clear, LOCK reads as logic 0 and has no meaning. The write one function of this bit is reserved for test, so this bit must always be written a 0. Reset clears the LOCK bit. 1 = VCO frequency correct or locked 0 = VCO frequency incorrect or unlocked ACQ — Acquisition Mode Bit When the AUTO bit is set, ACQ is a read-only bit that indicates whether the PLL is in acquisition mode or tracking mode. When the AUTO bit is clear, ACQ is a read/write bit that controls whether the PLL is in acquisition or tracking mode. In automatic bandwidth control mode (AUTO = 1), the last-written value from manual operation is stored in a temporary location and is recovered when manual operation resumes. Reset clears this bit, enabling acquisition mode. 1 = Tracking mode 0 = Acquisition mode 4.5.3 PLL Multiplier Select Register High The PLL multiplier select register high (PMSH) contains the programming information for the high byte of the modulo feedback divider. Address: $0038 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 MUL11 MUL10 MUL9 MUL8 Write: Reset: 0 0 0 0 0 0 0 0 =Unimplemented Figure 4-6. PLL Multiplier Select Register High (PMSH) MUL11–MUL8 — Multiplier Select Bits These read/write bits control the high byte of the modulo feedback divider that selects the VCO frequency multiplier N. (See 4.3.3 PLL Circuits and 4.3.6 Programming the PLL.) A value of $0000 in the multiplier select registers configures the modulo feedback divider the same as a value of $0001. Reset initializes the registers to $0040 for a default multiply value of 64. NOTE The multiplier select bits have built-in protection such that they cannot be written when the PLL is on (PLLON = 1). PMSH[7:4] — Unimplemented Bits These bits have no function and always read as logic 0s. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 72 Freescale Semiconductor

CGM Registers 4.5.4 PLL Multiplier Select Register Low The PLL multiplier select register low (PMSL) contains the programming information for the low byte of the modulo feedback divider. Address: $0038 Bit 7 6 5 4 3 2 1 Bit 0 Read: MUL7 MUL6 MUL5 MUL4 MUL3 MUL2 MUL1 MUL0 Write: Reset: 0 1 0 0 0 0 0 0 Figure 4-7. PLL Multiplier Select Register Low (PMSL) NOTE For applications using 1–8 MHz reference frequencies this register must be reprogrammed before enabling the PLL. The reset value of this register will cause applications using 1–8 MHz reference frequencies to become unstable if the PLL is enabled without programming an appropriate value. The programmed value must not allow the VCO clock to exceed 32 MHz. See 4.3.6 Programming the PLL for detailed instructions on choosing the proper value for PMSL. MUL7–MUL0 — Multiplier Select Bits These read/write bits control the low byte of the modulo feedback divider that selects the VCO frequency multiplier, N. (See 4.3.3 PLL Circuits and 4.3.6 Programming the PLL.) MUL7–MUL0 cannot be written when the PLLON bit in the PCTL is set. A value of $0000 in the multiplier select registers configures the modulo feedback divider the same as a value of $0001. Reset initializes the register to $40 for a default multiply value of 64. NOTE The multiplier select bits have built-in protection such that they cannot be written when the PLL is on (PLLON = 1). 4.5.5 PLL VCO Range Select Register NOTE PMRS may be called PVRS on other HC08 derivatives. The PLL VCO range select register (PMRS) contains the programming information required for the hardware configuration of the VCO. Address: $003A Bit 7 6 5 4 3 2 1 Bit 0 Read: VRS7 VRS6 VRS5 VRS4 VRS3 VRS2 VRS1 VRS0 Write: Reset: 0 1 0 0 0 0 0 0 Figure 4-8. PLL VCO Range Select Register (PMRS) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 73

Clock Generator Module (CGM) NOTE Verify that the value of the PMRS register is appropriate for the given reference and VCO clock frequencies before enabling the PLL. See 4.3.6 Programming the PLL for detailed instructions on selecting the proper value for these control bits. VRS7–VRS0 — VCO Range Select Bits These read/write bits control the hardware center-of-range linear multiplier L which, in conjunction with E (See 4.3.3 PLL Circuits, 4.3.6 Programming the PLL, and 4.5.1 PLL Control Register.), controls the hardware center-of-range frequency, f . VRS7–VRS0 cannot be written when the PLLON bit in the VRS PCTL is set. (See 4.3.7 Special Programming Exceptions.) A value of $00 in the VCO range select register disables the PLL and clears the BCS bit in the PLL control register (PCTL). (See 4.3.8 Base Clock Selector Circuit and 4.3.7 Special Programming Exceptions.). Reset initializes the register to $40 for a default range multiply value of 64. NOTE The VCO range select bits have built-in protection such that they cannot be written when the PLL is on (PLLON = 1) and such that the VCO clock cannot be selected as the source of the base clock (BCS = 1) if the VCO range select bits are all clear. The PLL VCO range select register must be programmed correctly. Incorrect programming can result in failure of the PLL to achieve lock. 4.6 Interrupts When the AUTO bit is set in the PLL bandwidth control register (PBWC), the PLL can generate a CPU interrupt request every time the LOCK bit changes state. The PLLIE bit in the PLL control register (PCTL) enables CPU interrupts from the PLL. PLLF, the interrupt flag in the PCTL, becomes set whether interrupts are enabled or not. When the AUTO bit is clear, CPU interrupts from the PLL are disabled and PLLF reads as logic 0. Software should read the LOCK bit after a PLL interrupt request to see if the request was due to an entry into lock or an exit from lock. When the PLL enters lock, the VCO clock, CGMVCLK, divided by two can be selected as the CGMOUT source by setting BCS in the PCTL. When the PLL exits lock, the VCO clock frequency is corrupt, and appropriate precautions should be taken. If the application is not frequency sensitive, interrupts should be disabled to prevent PLL interrupt service routines from impeding software performance or from exceeding stack limitations. NOTE Software can select the CGMVCLK divided by two as the CGMOUT source even if the PLL is not locked (LOCK = 0). Therefore, software should make sure the PLL is locked before setting the BCS bit. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 74 Freescale Semiconductor

Special Modes 4.7 Special Modes The WAIT instruction puts the MCU in low power-consumption standby modes. 4.7.1 Wait Mode The WAIT instruction does not affect the CGM. Before entering wait mode, software can disengage and turn off the PLL by clearing the BCS and PLLON bits in the PLL control register (PCTL) to save power. Less power-sensitive applications can disengage the PLL without turning it off, so that the PLL clock is immediately available at WAIT exit. This would be the case also when the PLL is to wake the MCU from wait mode, such as when the PLL is first enabled and waiting for LOCK or LOCK is lost. 4.7.2 Stop Mode If the OSCSTOPENB bit in the CONFIG register is cleared (default), then the STOP instruction disables the CGM (oscillator and phase locked loop) and holds low all CGM outputs (CGMXCLK, CGMOUT, and CGMINT). If the OSCSTOPENB bit in the CONFIG register is set, then the phase locked loop is shut off but the oscillator will continue to operate in stop mode. 4.7.3 CGM During Break Interrupts The system integration module (SIM) controls whether status bits in other modules can be cleared during the break state. The BCFE bit in the SIM break flag control register (SBFCR) enables software to clear status bits during the break state. See 16.7.3 Break Flag Control Register. To allow software to clear status bits during a break interrupt, write a logic 1 to the BCFE bit. If a status bit is cleared during the break state, it remains cleared when the MCU exits the break state. To protect the PLLF bit during the break state, write a logic 0 to the BCFE bit. With BCFE at logic 0 (its default state), software can read and write the PLL control register during the break state without affecting the PLLF bit. 4.8 Acquisition/Lock Time Specifications The acquisition and lock times of the PLL are, in many applications, the most critical PLL design parameters. Proper design and use of the PLL ensures the highest stability and lowest acquisition/lock times. 4.8.1 Acquisition/Lock Time Definitions Typical control systems refer to the acquisition time or lock time as the reaction time, within specified tolerances, of the system to a step input. In a PLL, the step input occurs when the PLL is turned on or when it suffers a noise hit. The tolerance is usually specified as a percent of the step input or when the output settles to the desired value plus or minus a percent of the frequency change. Therefore, the reaction time is constant in this definition, regardless of the size of the step input. For example, consider a system with a 5 percent acquisition time tolerance. If a command instructs the system to change from 0 Hz to 1 MHz, the acquisition time is the time taken for the frequency to reach 1 MHz ±50 kHz. Fifty kHz = 5% of the 1-MHz step input. If the system is operating at 1 MHz and suffers a –100-kHz noise hit, the acquisition time is the time taken to return from 900 kHz to 1 MHz ±5 kHz. Five kHz = 5% of the 100-kHz step input. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 75

Clock Generator Module (CGM) Other systems refer to acquisition and lock times as the time the system takes to reduce the error between the actual output and the desired output to within specified tolerances. Therefore, the acquisition or lock time varies according to the original error in the output. Minor errors may not even be registered. Typical PLL applications prefer to use this definition because the system requires the output frequency to be within a certain tolerance of the desired frequency regardless of the size of the initial error. 4.8.2 Parametric Influences on Reaction Time Acquisition and lock times are designed to be as short as possible while still providing the highest possible stability. These reaction times are not constant, however. Many factors directly and indirectly affect the acquisition time. The most critical parameter which affects the reaction times of the PLL is the reference frequency, f . RCLK This frequency is the input to the phase detector and controls how often the PLL makes corrections. For stability, the corrections must be small compared to the desired frequency, so several corrections are required to reduce the frequency error. Therefore, the slower the reference the longer it takes to make these corrections. This parameter is under user control via the choice of crystal frequency f . (See XCLK 4.3.3 PLL Circuits and 4.3.6 Programming the PLL.) Another critical parameter is the external filter network. The PLL modifies the voltage on the VCO by adding or subtracting charge from capacitors in this network. Therefore, the rate at which the voltage changes for a given frequency error (thus change in charge) is proportional to the capacitance. The size of the capacitor also is related to the stability of the PLL. If the capacitor is too small, the PLL cannot make small enough adjustments to the voltage and the system cannot lock. If the capacitor is too large, the PLL may not be able to adjust the voltage in a reasonable time. (See 4.8.3 Choosing a Filter.) Also important is the operating voltage potential applied to V . The power supply potential alters the DDA characteristics of the PLL. A fixed value is best. Variable supplies, such as batteries, are acceptable if they vary within a known range at very slow speeds. Noise on the power supply is not acceptable, because it causes small frequency errors which continually change the acquisition time of the PLL. Temperature and processing also can affect acquisition time because the electrical characteristics of the PLL change. The part operates as specified as long as these influences stay within the specified limits. External factors, however, can cause drastic changes in the operation of the PLL. These factors include noise injected into the PLL through the filter capacitor, filter capacitor leakage, stray impedances on the circuit board, and even humidity or circuit board contamination. 4.8.3 Choosing a Filter As described in 4.8.2 Parametric Influences on Reaction Time, the external filter network is critical to the stability and reaction time of the PLL. The PLL is also dependent on reference frequency and supply voltage. Figure 4-9 shows two types of filter circuits. In low-cost applications, where stability and reaction time of the PLL are not critical, the three component filter network shown in Figure 4-9 (B) can be replaced by a single capacitor, C , as shown in shown in Figure 4-9 (A). Refer to Table 4-5 for recommended filter F components at various reference frequencies. For reference frequencies between the values listed in the table, extrapolate to the nearest common capacitor value. In general, a slightly larger capacitor provides more stability at the expense of increased lock time. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 76 Freescale Semiconductor

Acquisition/Lock Time Specifications CGMXFC CGMXFC R F1 C C F2 F C F1 VSSA VSSA (A) (B) Figure 4-9. PLL Filter Table 4-5. Example Filter Component Values f C C R C RCLK F1 F2 F1 F 1 MHz 8.2 nF 820 pF 2k 18 nF 2 MHz 4.7 nF 470 pF 2k 6.8 nF 3 MHz 3.3 nF 330 pF 2k 5.6 nF 4 MHz 2.2 nF 220 pF 2k 4.7 nF 5 MHz 1.8 nF 180 pF 2k 3.9 nF 6 MHz 1.5 nF 150 pF 2k 3.3 nF 7 MHz 1.2 nF 120 pF 2k 2.7 nF 8 MHz 1 nF 100 pF 2k 2.2 nF MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 77

Clock Generator Module (CGM) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 78 Freescale Semiconductor

Chapter 5 Configuration Register (CONFIG) 5.1 Introduction This section describes the configuration registers, CONFIG1 and CONFIG2. The configuration registers enable or disable these options: (cid:129) Stop mode recovery time (32 CGMXCLK cycles or 4096 CGMXCLK cycles) (cid:129) COP timeout period (218 – 24 or 213 – 24 COPCLK cycles) (cid:129) STOP instruction (cid:129) Computer operating properly module (COP) (cid:129) Low-voltage inhibit (LVI) module control and voltage trip point selection (cid:129) Enable/disable the oscillator (OSC) during stop mode (cid:129) Enable/disable an extra divide by 128 prescaler in timebase module (cid:129) Enable for MSCAN 5.2 Functional Description The configuration registers are used in the initialization of various options. The configuration registers can be written once after each reset. All of the configuration register bits are cleared during reset. Since the various options affect the operation of the microcontroller unit (MCU), it is recommended that these registers be written immediately after reset. The configuration registers are located at $001E and $001F and may be read at anytime. NOTE On a FLASH device, the options except LVI5OR3 are one-time writable by the user after each reset. The LVI5OR3 bit is one-time writable by the user only after each POR (power-on reset). The CONFIG registers are not in the FLASH memory but are special registers containing one-time writable latches after each reset. Upon a reset, the CONFIG registers default to predetermined settings as shown in Figure 5-1 and Figure 5-2. Address: $001E Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 MSCANEN TMCLKSEL OSCENINSTOP ESCIBDSRC Write: Reset: 0 0 0 0 See note 0 0 1 Note: MSCANEN is only reset via POR (power-on reset). = Unimplemented Figure 5-1. Configuration Register 2 (CONFIG2) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 79

Configuration Register (CONFIG) Address: $001F Bit 7 6 5 4 3 2 1 Bit 0 Read: COPRS LVISTOP LVIRSTD LVIPWRD LVI5OR3 SSREC STOP COPD Write: Reset: 0 0 0 0 See note 0 0 0 Note: LVI5OR3 bit is only reset via POR (power-on reset). Figure 5-2. Configuration Register 1 (CONFIG1) MSCANEN— MSCAN08 Enable Bit Setting the MSCANEN enables the MSCAN08 module and allows the MSCAN08 to use the PTC0/PTC1 pins. See Chapter 12 MSCAN08 Controller (MSCAN08) for a more detailed description of the MSCAN08 operation. 1 = Enables MSCAN08 module 0 = Disables the MSCAN08 module NOTE The MSCANEN bit is cleared by a power-on reset (POR) only. Other resets will leave this bit unaffected. TMCLKSEL— Timebase Clock Select Bit TMCLKSEL enables an extra divide-by-128 prescaler in the timebase module. Setting this bit enables the extra prescaler and clearing this bit disables it. See Chapter 4 Clock Generator Module (CGM) for a more detailed description of the external clock operation. 1 = Enables extra divide-by-128 prescaler in timebase module 0 = Disables extra divide-by-128 prescaler in timebase module OSCENINSTOP — Oscillator Enable In Stop Mode Bit OSCENINSTOP, when set, will enable the oscillator to continue to generate clocks in stop mode. See Chapter 4 Clock Generator Module (CGM). This function is used to keep the timebase running while the reset of the MCU stops. See Chapter 18 Timebase Module (TBM). When clear, oscillator will cease to generate clocks while in stop mode. The default state for this option is clear, disabling the oscillator in stop mode. 1 = Oscillator enabled to operate during stop mode 0 = Oscillator disabled during stop mode (default) ESCIBDSRC — SCI Baud Rate Clock Source Bit ESCIBDSRC controls the clock source used for the serial communications interface (SCI). The setting of this bit affects the frequency at which the SCI operates.See Chapter 15 Enhanced Serial Communications Interface (ESCI) Module. 1 = Internal data bus clock used as clock source for SCI (default) 0 = External oscillator used as clock source for SCI COPRS — COP Rate Select Bit COPD selects the COP timeout period. Reset clears COPRS. See Chapter 6 Computer Operating Properly (COP) Module 1 = COP timeout period = 213 – 24 COPCLK cycles 0 = COP timeout period = 218 – 24 COPCLK cycles MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 80 Freescale Semiconductor

Functional Description LVISTOP — LVI Enable in Stop Mode Bit When the LVIPWRD bit is clear, setting the LVISTOP bit enables the LVI to operate during stop mode. Reset clears LVISTOP. 1 = LVI enabled during stop mode 0 = LVI disabled during stop mode LVIRSTD — LVI Reset Disable Bit LVIRSTD disables the reset signal from the LVI module. See Chapter 11 Low-Voltage Inhibit (LVI). 1 = LVI module resets disabled 0 = LVI module resets enabled LVIPWRD — LVI Power Disable Bit LVIPWRD disables the LVI module. See Chapter 11 Low-Voltage Inhibit (LVI). 1 = LVI module power disabled 0 = LVI module power enabled LVI5OR3 — LVI 5-V or 3-V Operating Mode Bit LVI5OR3 selects the voltage operating mode of the LVI module (see Chapter 11 Low-Voltage Inhibit (LVI)). The voltage mode selected for the LVI should match the operating V (see Chapter 21 DD Electrical Specifications) for the LVI’s voltage trip points for each of the modes. 1 = LVI operates in 5-V mode 0 = LVI operates in 3-V mode NOTE The LVI5OR3 bit is cleared by a power-on reset (POR) only. Other resets will leave this bit unaffected. SSREC — Short Stop Recovery Bit SSREC enables the CPU to exit stop mode with a delay of 32 CGMXCLK cycles instead of a 4096-CGMXCLK cycle delay. 1 = Stop mode recovery after 32 CGMXCLK cycles 0 = Stop mode recovery after 4096 CGMXCLCK cycles NOTE Exiting stop mode by an LVI reset will result in the long stop recovery. If the system clock source selected is the internal oscillator or the external crystal and the OSCENINSTOP configuration bit is not set, the oscillator will be disabled during stop mode. The short stop recovery does not provide enough time for oscillator stabilization and for this reason the SSREC bit should not be set. The system stabilization time for power-on reset and long stop recovery (both 4096 CGMXCLK cycles) gives a delay longer than the LVI enable time for these startup scenarios. There is no period where the MCU is not protected from a low-power condition. However, when using the short stop recovery configuration option, the 32-CGMXCLK delay must be greater than the LVI’s turn on time to avoid a period in startup where the LVI is not protecting the MCU. STOP — STOP Instruction Enable Bit STOP enables the STOP instruction. 1 = STOP instruction enabled 0 = STOP instruction treated as illegal opcode MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 81

Configuration Register (CONFIG) COPD — COP Disable Bit COPD disables the COP module. See Chapter 6 Computer Operating Properly (COP) Module. 1 = COP module disabled 0 = COP module enabled MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 82 Freescale Semiconductor

Chapter 6 Computer Operating Properly (COP) Module 6.1 Introduction The computer operating properly (COP) module contains a free-running counter that generates a reset if allowed to overflow. The COP module helps software recover from runaway code. Prevent a COP reset by clearing the COP counter periodically. The COP module can be disabled through the COPD bit in the CONFIG register. 6.2 Functional Description Figure 6-1 shows the structure of the COP module. SIM MODULE BUSCLKX4 12-BIT SIM COUNTER SIM RESET CIRCUIT RESET STATUS REGISTER 2 INTERNAL RESET SOURCES(1) CLEAR ALL STAGES CLEAR STAGES 5–1 TIMEOUT P O RESET VECTOR FETCH C COPCTL WRITE COP CLOCK COP MODULE 6-BIT COP COUNTER COPEN (FROM SIM) COPD (FROM CONFIG1) CLEAR RESET COP COUNTER COPCTL WRITE COP RATE SELECT (COPRS FROM CONFIG1) 1. See Chapter 16 System Integration Module (SIM) for more details. Figure 6-1. COP Block Diagram MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 83

Computer Operating Properly (COP) Module The COP counter is a free-running 6-bit counter preceded by a 12-bit prescaler counter. If not cleared by software, the COP counter overflows and generates an asynchronous reset after 218– 24 or 213– 24 CGMXCLK cycles, depending on the state of the COP rate select bit, COPRS, in the configuration register. With a 213– 24 CGMXCLK cycle overflow option, a 4.9152-MHz crystal gives a COP timeout period of 53.3 ms. Writing any value to location $FFFF before an overflow occurs prevents a COP reset by clearing the COP counter and stages 12–5 of the prescaler. NOTE Service the COP immediately after reset and before entering or after exiting stop mode to guarantee the maximum time before the first COP counter overflow. A COP reset pulls the RST pin low for 32 CGMXCLK cycles and sets the COP bit in the reset status register (RSR). In monitor mode, the COP is disabled if the RST pin or the IRQ1 is held at V . During the break state, TST V on the RST pin disables the COP. TST NOTE Place COP clearing instructions in the main program and not in an interrupt subroutine. Such an interrupt subroutine could keep the COP from generating a reset even while the main program is not working properly. 6.3 I/O Signals The following paragraphs describe the signals shown in Figure 6-1. 6.3.1 CGMXCLK CGMXCLK is the crystal oscillator output signal. CGMXCLK frequency is equal to the crystal frequency. 6.3.2 STOP Instruction The STOP instruction clears the COP prescaler. 6.3.3 COPCTL Write Writing any value to the COP control register (COPCTL) clears the COP counter and clears bits 12–5 of the prescaler. Reading the COP control register returns the low byte of the reset vector. See 6.4 COP Control Register. 6.3.4 Power-On Reset The power-on reset (POR) circuit clears the COP prescaler 4096 CGMXCLK cycles after power-up. 6.3.5 Internal Reset An internal reset clears the COP prescaler and the COP counter. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 84 Freescale Semiconductor

COP Control Register 6.3.6 Reset Vector Fetch A reset vector fetch occurs when the vector address appears on the data bus. A reset vector fetch clears the COP prescaler. 6.3.7 COPD (COP Disable) The COPD signal reflects the state of the COP disable bit (COPD) in the configuration register. See Chapter 5 Configuration Register (CONFIG). 6.3.8 COPRS (COP Rate Select) The COPRS signal reflects the state of the COP rate select bit (COPRS) in the configuration register. See Chapter 5 Configuration Register (CONFIG). 6.4 COP Control Register The COP control register (COPCTL) is located at address $FFFF and overlaps the reset vector. Writing any value to $FFFF clears the COP counter and starts a new timeout period. Reading location $FFFF returns the low byte of the reset vector. Address: $FFFF Bit 7 6 5 4 3 2 1 Bit 0 Read: Low byte of reset vector Write: Clear COP counter Reset: Unaffected by reset Figure 6-2. COP Control Register (COPCTL) 6.5 Interrupts The COP does not generate central processor unit (CPU) interrupt requests. 6.6 Monitor Mode When monitor mode is entered with V on the IRQ pin, the COP is disabled as long as V remains TST TST on the IRQ pin or the RST pin. When monitor mode is entered by having blank reset vectors and not having V on the IRQ pin, the COP is automatically disabled until a POR occurs. TST 6.7 Low-Power Modes The WAIT and STOP instructions put the microcontroller unit (MCU) in low power-consumption standby modes. 6.7.1 Wait Mode The COP remains active during wait mode. If COP is enabled, a reset will occur at COP timeout. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 85

Computer Operating Properly (COP) Module 6.7.2 Stop Mode Stop mode turns off the CGMXCLK input to the COP and clears the COP prescaler. Service the COP immediately before entering or after exiting stop mode to ensure a full COP timeout period after entering or exiting stop mode. To prevent inadvertently turning off the COP with a STOP instruction, a configuration option is available that disables the STOP instruction. When the STOP bit in the configuration register has the STOP instruction disabled, execution of a STOP instruction results in an illegal opcode reset. 6.8 COP Module During Break Mode The COP is disabled during a break interrupt when V is present on the RST pin. TST MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 86 Freescale Semiconductor

Chapter 7 Central Processor Unit (CPU) 7.1 Introduction The M68HC08 CPU (central processor unit) is an enhanced and fully object-code-compatible version of the M68HC05 CPU. The CPU08 Reference Manual (document order number CPU08RM/AD) contains a description of the CPU instruction set, addressing modes, and architecture. 7.2 Features Features of the CPU include: (cid:129) Object code fully upward-compatible with M68HC05 Family (cid:129) 16-bit stack pointer with stack manipulation instructions (cid:129) 16-bit index register with x-register manipulation instructions (cid:129) 8-MHz CPU internal bus frequency (cid:129) 64-Kbyte program/data memory space (cid:129) 16 addressing modes (cid:129) Memory-to-memory data moves without using accumulator (cid:129) Fast 8-bit by 8-bit multiply and 16-bit by 8-bit divide instructions (cid:129) Enhanced binary-coded decimal (BCD) data handling (cid:129) Modular architecture with expandable internal bus definition for extension of addressing range beyond 64 Kbytes (cid:129) Low-power stop and wait modes 7.3 CPU Registers Figure 7-1 shows the five CPU registers. CPU registers are not part of the memory map. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 87

Central Processor Unit (CPU) 7 0 ACCUMULATOR (A) 15 0 H X INDEX REGISTER (H:X) 15 0 STACK POINTER (SP) 15 0 PROGRAM COUNTER (PC) 7 0 V 1 1 H I N Z C CONDITION CODE REGISTER (CCR) CARRY/BORROW FLAG ZERO FLAG NEGATIVE FLAG INTERRUPT MASK HALF-CARRY FLAG TWO’S COMPLEMENT OVERFLOW FLAG Figure 7-1. CPU Registers 7.3.1 Accumulator The accumulator is a general-purpose 8-bit register. The CPU uses the accumulator to hold operands and the results of arithmetic/logic operations. Bit 7 6 5 4 3 2 1 Bit 0 Read: Write: Reset: Unaffected by reset Figure 7-2. Accumulator (A) 7.3.2 Index Register The 16-bit index register allows indexed addressing of a 64-Kbyte memory space. H is the upper byte of the index register, and X is the lower byte. H:X is the concatenated 16-bit index register. In the indexed addressing modes, the CPU uses the contents of the index register to determine the conditional address of the operand. The index register can serve also as a temporary data storage location. Bit Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Read: Write: Reset: 0 0 0 0 0 0 0 0 X X X X X X X X X = Indeterminate Figure 7-3. Index Register (H:X) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 88 Freescale Semiconductor

CPU Registers 7.3.3 Stack Pointer The stack pointer is a 16-bit register that contains the address of the next location on the stack. During a reset, the stack pointer is preset to $00FF. The reset stack pointer (RSP) instruction sets the least significant byte to $FF and does not affect the most significant byte. The stack pointer decrements as data is pushed onto the stack and increments as data is pulled from the stack. In the stack pointer 8-bit offset and 16-bit offset addressing modes, the stack pointer can function as an index register to access data on the stack. The CPU uses the contents of the stack pointer to determine the conditional address of the operand. Bit Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Read: Write: Reset: 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 Figure 7-4. Stack Pointer (SP) NOTE The location of the stack is arbitrary and may be relocated anywhere in random-access memory (RAM). Moving the SP out of page 0 ($0000 to $00FF) frees direct address (page 0) space. For correct operation, the stack pointer must point only to RAM locations. 7.3.4 Program Counter The program counter is a 16-bit register that contains the address of the next instruction or operand to be fetched. Normally, the program counter automatically increments to the next sequential memory location every time an instruction or operand is fetched. Jump, branch, and interrupt operations load the program counter with an address other than that of the next sequential location. During reset, the program counter is loaded with the reset vector address located at $FFFE and $FFFF. The vector address is the address of the first instruction to be executed after exiting the reset state. Bit Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Read: Write: Reset: Loaded with vector from $FFFE and $FFFF Figure 7-5. Program Counter (PC) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 89

Central Processor Unit (CPU) 7.3.5 Condition Code Register The 8-bit condition code register contains the interrupt mask and five flags that indicate the results of the instruction just executed. Bits 6 and 5 are set permanently to 1. The following paragraphs describe the functions of the condition code register. Bit 7 6 5 4 3 2 1 Bit 0 Read: V 1 1 H I N Z C Write: Reset: X 1 1 X 1 X X X X = Indeterminate Figure 7-6. Condition Code Register (CCR) V — Overflow Flag The CPU sets the overflow flag when a two's complement overflow occurs. The signed branch instructions BGT, BGE, BLE, and BLT use the overflow flag. 1 = Overflow 0 = No overflow H — Half-Carry Flag The CPU sets the half-carry flag when a carry occurs between accumulator bits 3 and 4 during an add-without-carry (ADD) or add-with-carry (ADC) operation. The half-carry flag is required for binary-coded decimal (BCD) arithmetic operations. The DAA instruction uses the states of the H and C flags to determine the appropriate correction factor. 1 = Carry between bits 3 and 4 0 = No carry between bits 3 and 4 I — Interrupt Mask When the interrupt mask is set, all maskable CPU interrupts are disabled. CPU interrupts are enabled when the interrupt mask is cleared. When a CPU interrupt occurs, the interrupt mask is set automatically after the CPU registers are saved on the stack, but before the interrupt vector is fetched. 1 = Interrupts disabled 0 = Interrupts enabled NOTE To maintain M6805 Family compatibility, the upper byte of the index register (H) is not stacked automatically. If the interrupt service routine modifies H, then the user must stack and unstack H using the PSHH and PULH instructions. After the I bit is cleared, the highest-priority interrupt request is serviced first. A return-from-interrupt (RTI) instruction pulls the CPU registers from the stack and restores the interrupt mask from the stack. After any reset, the interrupt mask is set and can be cleared only by the clear interrupt mask software instruction (CLI). N — Negative Flag The CPU sets the negative flag when an arithmetic operation, logic operation, or data manipulation produces a negative result, setting bit 7 of the result. 1 = Negative result 0 = Non-negative result MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 90 Freescale Semiconductor

Arithmetic/Logic Unit (ALU) Z — Zero Flag The CPU sets the zero flag when an arithmetic operation, logic operation, or data manipulation produces a result of $00. 1 = Zero result 0 = Non-zero result C — Carry/Borrow Flag The CPU sets the carry/borrow flag when an addition operation produces a carry out of bit 7 of the accumulator or when a subtraction operation requires a borrow. Some instructions — such as bit test and branch, shift, and rotate — also clear or set the carry/borrow flag. 1 = Carry out of bit 7 0 = No carry out of bit 7 7.4 Arithmetic/Logic Unit (ALU) The ALU performs the arithmetic and logic operations defined by the instruction set. Refer to the CPU08 Reference Manual (document order number CPU08RM/AD) for a description of the instructions and addressing modes and more detail about the architecture of the CPU. 7.5 Low-Power Modes The WAIT and STOP instructions put the MCU in low power-consumption standby modes. 7.5.1 Wait Mode The WAIT instruction: (cid:129) Clears the interrupt mask (I bit) in the condition code register, enabling interrupts. After exit from wait mode by interrupt, the I bit remains clear. After exit by reset, the I bit is set. (cid:129) Disables the CPU clock 7.5.2 Stop Mode The STOP instruction: (cid:129) Clears the interrupt mask (I bit) in the condition code register, enabling external interrupts. After exit from stop mode by external interrupt, the I bit remains clear. After exit by reset, the I bit is set. (cid:129) Disables the CPU clock After exiting stop mode, the CPU clock begins running after the oscillator stabilization delay. 7.6 CPU During Break Interrupts If a break module is present on the MCU, the CPU starts a break interrupt by: (cid:129) Loading the instruction register with the SWI instruction (cid:129) Loading the program counter with $FFFC:$FFFD or with $FEFC:$FEFD in monitor mode The break interrupt begins after completion of the CPU instruction in progress. If the break address register match occurs on the last cycle of a CPU instruction, the break interrupt begins immediately. A return-from-interrupt instruction (RTI) in the break routine ends the break interrupt and returns the MCU to normal operation if the break interrupt has been deasserted. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 91

Central Processor Unit (CPU) 7.7 Instruction Set Summary Table 7-1 provides a summary of the M68HC08 instruction set. Table 7-1. Instruction Set Summary (Sheet 1 of 6) SFoourrmce Operation Description oEnf fCeCctR dressde code erand cles V H I N Z C do p p y AM O O C ADC #opr IMM A9 ii 2 ADC opr DIR B9 dd 3 ADC opr EXT C9 hh ll 4 ADC opr,X IX2 D9 ee ff 4 Add with Carry A ← (A) + (M) + (C) (cid:21) (cid:21) – (cid:21) (cid:21) (cid:21) ADC opr,X IX1 E9 ff 3 ADC ,X IX F9 2 ADC opr,SP SP1 9EE9 ff 4 ADC opr,SP SP2 9ED9 ee ff 5 ADD #opr IMM AB ii 2 ADD opr DIR BB dd 3 ADD opr EXT CB hh ll 4 ADD opr,X IX2 DB ee ff 4 Add without Carry A ← (A) + (M) (cid:21) (cid:21) – (cid:21) (cid:21) (cid:21) ADD opr,X IX1 EB ff 3 ADD ,X IX FB 2 ADD opr,SP SP1 9EEB ff 4 ADD opr,SP SP2 9EDB ee ff 5 AIS #opr Add Immediate Value (Signed) to SP SP ← (SP) + (16 « M) – – – – – – IMM A7 ii 2 AIX #opr Add Immediate Value (Signed) to H:X H:X ← (H:X) + (16 « M) – – – – – – IMM AF ii 2 AND #opr IMM A4 ii 2 AND opr DIR B4 dd 3 AND opr EXT C4 hh ll 4 AND opr,X IX2 D4 ee ff 4 Logical AND A ← (A) & (M) 0 – – (cid:21) (cid:21) – AND opr,X IX1 E4 ff 3 AND ,X IX F4 2 AND opr,SP SP1 9EE4 ff 4 AND opr,SP SP2 9ED4 ee ff 5 ASL opr DIR 38 dd 4 ASLA INH 48 1 ASLX Arithmetic Shift Left INH 58 1 C 0 (cid:21) – – (cid:21) (cid:21) (cid:21) ASL opr,X (Same as LSL) IX1 68 ff 4 ASL ,X b7 b0 IX 78 3 ASL opr,SP SP1 9E68 ff 5 ASR opr DIR 37 dd 4 ASRA INH 47 1 ASRX Arithmetic Shift Right C (cid:21) – – (cid:21) (cid:21) (cid:21) INH 57 1 ASR opr,X IX1 67 ff 4 ASR opr,X b7 b0 IX 77 3 ASR opr,SP SP1 9E67 ff 5 BCC rel Branch if Carry Bit Clear PC ← (PC) + 2 + rel ? (C) = 0 – – – – – – REL 24 rr 3 DIR (b0) 11 dd 4 DIR (b1) 13 dd 4 DIR (b2) 15 dd 4 DIR (b3) 17 dd 4 BCLR n, opr Clear Bit n in M Mn ← 0 – – – – – – DIR (b4) 19 dd 4 DIR (b5) 1B dd 4 DIR (b6) 1D dd 4 DIR (b7) 1F dd 4 BCS rel Branch if Carry Bit Set (Same as BLO) PC ← (PC) + 2 + rel ? (C) = 1 – – – – – – REL 25 rr 3 BEQ rel Branch if Equal PC ← (PC) + 2 + rel ? (Z) = 1 – – – – – – REL 27 rr 3 BGE opr Branch if Greater Than or Equal To PC ← (PC) + 2 + rel ? (N ⊕ V) = 0 – – – – – – REL 90 rr 3 (Signed Operands) BGT opr Branch if Greater Than (Signed PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 0 – – – – – – REL 92 rr 3 Operands) BHCC rel Branch if Half Carry Bit Clear PC ← (PC) + 2 + rel ? (H) = 0 – – – – – – REL 28 rr 3 BHCS rel Branch if Half Carry Bit Set PC ← (PC) + 2 + rel ? (H) = 1 – – – – – – REL 29 rr 3 BHI rel Branch if Higher PC ← (PC) + 2 + rel ? (C) | (Z) = 0 – – – – – – REL 22 rr 3 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 92 Freescale Semiconductor

Instruction Set Summary Table 7-1. Instruction Set Summary (Sheet 2 of 6) SFoourrmce Operation Description oEnf fCeCctR dressde code erand cles V H I N Z C do p p y AM O O C Branch if Higher or Same BHS rel PC ← (PC) + 2 + rel ? (C) = 0 – – – – – – REL 24 rr 3 (Same as BCC) BIH rel Branch if IRQ Pin High PC ← (PC) + 2 + rel ? IRQ = 1 – – – – – – REL 2F rr 3 BIL rel Branch if IRQ Pin Low PC ← (PC) + 2 + rel ? IRQ = 0 – – – – – – REL 2E rr 3 BIT #opr IMM A5 ii 2 BIT opr DIR B5 dd 3 BIT opr EXT C5 hh ll 4 BIT opr,X IX2 D5 ee ff 4 Bit Test (A) & (M) 0 – – (cid:21) (cid:21) – BIT opr,X IX1 E5 ff 3 BIT ,X IX F5 2 BIT opr,SP SP1 9EE5 ff 4 BIT opr,SP SP2 9ED5 ee ff 5 BLE opr Branch if Less Than or Equal To PC ← (PC) + 2 + rel ? (Z) | (N ⊕ V) = 1 – – – – – – REL 93 rr 3 (Signed Operands) BLO rel Branch if Lower (Same as BCS) PC ← (PC) + 2 + rel ? (C) = 1 – – – – – – REL 25 rr 3 BLS rel Branch if Lower or Same PC ← (PC) + 2 + rel ? (C) | (Z) = 1 – – – – – – REL 23 rr 3 BLT opr Branch if Less Than (Signed Operands) PC ← (PC) + 2 + rel ? (N ⊕ V) =1 – – – – – – REL 91 rr 3 BMC rel Branch if Interrupt Mask Clear PC ← (PC) + 2 + rel ? (I) = 0 – – – – – – REL 2C rr 3 BMI rel Branch if Minus PC ← (PC) + 2 + rel ? (N) = 1 – – – – – – REL 2B rr 3 BMS rel Branch if Interrupt Mask Set PC ← (PC) + 2 + rel ? (I) = 1 – – – – – – REL 2D rr 3 BNE rel Branch if Not Equal PC ← (PC) + 2 + rel ? (Z) = 0 – – – – – – REL 26 rr 3 BPL rel Branch if Plus PC ← (PC) + 2 + rel ? (N) = 0 – – – – – – REL 2A rr 3 BRA rel Branch Always PC ← (PC) + 2 + rel – – – – – – REL 20 rr 3 DIR (b0) 01 dd rr 5 DIR (b1) 03 dd rr 5 DIR (b2) 05 dd rr 5 DIR (b3) 07 dd rr 5 BRCLR n,opr,rel Branch if Bit n in M Clear PC ← (PC) + 3 + rel ? (Mn) = 0 – – – – – (cid:21) DIR (b4) 09 dd rr 5 DIR (b5) 0B dd rr 5 DIR (b6) 0D dd rr 5 DIR (b7) 0F dd rr 5 BRN rel Branch Never PC ← (PC) + 2 – – – – – – REL 21 rr 3 DIR (b0) 00 dd rr 5 DIR (b1) 02 dd rr 5 DIR (b2) 04 dd rr 5 DIR (b3) 06 dd rr 5 BRSET n,opr,rel Branch if Bit n in M Set PC ← (PC) + 3 + rel ? (Mn) = 1 – – – – – (cid:21) DIR (b4) 08 dd rr 5 DIR (b5) 0A dd rr 5 DIR (b6) 0C dd rr 5 DIR (b7) 0E dd rr 5 DIR (b0) 10 dd 4 DIR (b1) 12 dd 4 DIR (b2) 14 dd 4 DIR (b3) 16 dd 4 BSET n,opr Set Bit n in M Mn ← 1 – – – – – – DIR (b4) 18 dd 4 DIR (b5) 1A dd 4 DIR (b6) 1C dd 4 DIR (b7) 1E dd 4 PC ← (PC) + 2; push (PCL) SP ← (SP) – 1; push (PCH) BSR rel Branch to Subroutine – – – – – – REL AD rr 4 SP ← (SP) – 1 PC ← (PC) + rel CBEQ opr,rel PC ← (PC) + 3 + rel ? (A) – (M) = $00 DIR 31 dd rr 5 CBEQA #opr,rel PC ← (PC) + 3 + rel ? (A) – (M) = $00 IMM 41 ii rr 4 CBEQX #opr,rel PC ← (PC) + 3 + rel ? (X) – (M) = $00 IMM 51 ii rr 4 Compare and Branch if Equal – – – – – – CBEQ opr,X+,rel PC ← (PC) + 3 + rel ? (A) – (M) = $00 IX1+ 61 ff rr 5 CBEQ X+,rel PC ← (PC) + 2 + rel ? (A) – (M) = $00 IX+ 71 rr 4 CBEQ opr,SP,rel PC ← (PC) + 4 + rel ? (A) – (M) = $00 SP1 9E61 ff rr 6 CLC Clear Carry Bit C ← 0 – – – – – 0 INH 98 1 CLI Clear Interrupt Mask I ← 0 – – 0 – – – INH 9A 2 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 93

Central Processor Unit (CPU) Table 7-1. Instruction Set Summary (Sheet 3 of 6) SFoourrmce Operation Description oEnf fCeCctR dressde code erand cles V H I N Z C do p p y AM O O C CLR opr M ← $00 DIR 3F dd 3 CLRA A ← $00 INH 4F 1 CLRX X ← $00 INH 5F 1 CLRH Clear H ← $00 0 – – 0 1 – INH 8C 1 CLR opr,X M ← $00 IX1 6F ff 3 CLR ,X M ← $00 IX 7F 2 CLR opr,SP M ← $00 SP1 9E6F ff 4 CMP #opr IMM A1 ii 2 CMP opr DIR B1 dd 3 CMP opr EXT C1 hh ll 4 CMP opr,X IX2 D1 ee ff 4 Compare A with M (A) – (M) (cid:21) – – (cid:21) (cid:21) (cid:21) CMP opr,X IX1 E1 ff 3 CMP ,X IX F1 2 CMP opr,SP SP1 9EE1 ff 4 CMP opr,SP SP2 9ED1 ee ff 5 COM opr M ← (M) = $FF – (M) DIR 33 dd 4 COMA A ← (A) = $FF – (M) INH 43 1 COMX X ← (X) = $FF – (M) INH 53 1 Complement (One’s Complement) 0 – – (cid:21) (cid:21) 1 COM opr,X M ← (M) = $FF – (M) IX1 63 ff 4 COM ,X M ← (M) = $FF – (M) IX 73 3 COM opr,SP M ← (M) = $FF – (M) SP1 9E63 ff 5 CPHX #opr IMM 65 ii ii+1 3 Compare H:X with M (H:X) – (M:M + 1) (cid:21) – – (cid:21) (cid:21) (cid:21) CPHX opr DIR 75 dd 4 CPX #opr IMM A3 ii 2 CPX opr DIR B3 dd 3 CPX opr EXT C3 hh ll 4 CPX ,X IX2 D3 ee ff 4 Compare X with M (X) – (M) (cid:21) – – (cid:21) (cid:21) (cid:21) CPX opr,X IX1 E3 ff 3 CPX opr,X IX F3 2 CPX opr,SP SP1 9EE3 ff 4 CPX opr,SP SP2 9ED3 ee ff 5 DAA Decimal Adjust A (A)10 U – – (cid:21) (cid:21) (cid:21) INH 72 2 A ← (A) – 1 or M ← (M) – 1 or X ← (X) – 1 5 DBNZ opr,rel PC ← (PC) + 3 + rel ? (result) ≠ 0 DIR 3B dd rr 3 DBNZA rel PC ← (PC) + 2 + rel ? (result) ≠ 0 INH 4B rr 3 DBNZX rel Decrement and Branch if Not Zero PC ← (PC) + 2 + rel ? (result) ≠ 0 – – – – – – INH 5B rr 5 DBNZ opr,X,rel PC ← (PC) + 3 + rel ? (result) ≠ 0 IX1 6B ff rr 4 DBNZ X,rel PC ← (PC) + 2 + rel ? (result) ≠ 0 IX 7B rr 6 DBNZ opr,SP,rel PC ← (PC) + 4 + rel ? (result) ≠ 0 SP1 9E6B ff rr DEC opr M ← (M) – 1 DIR 3A dd 4 DECA A ← (A) – 1 INH 4A 1 DECX X ← (X) – 1 INH 5A 1 Decrement (cid:21) – – (cid:21) (cid:21) – DEC opr,X M ← (M) – 1 IX1 6A ff 4 DEC ,X M ← (M) – 1 IX 7A 3 DEC opr,SP M ← (M) – 1 SP1 9E6A ff 5 A ← (H:A)/(X) DIV Divide – – – – (cid:21) (cid:21) INH 52 7 H ← Remainder EOR #opr IMM A8 ii 2 EOR opr DIR B8 dd 3 EOR opr EXT C8 hh ll 4 EOR opr,X Exclusive OR M with A A ← (A ⊕ M) 0 – – (cid:21) (cid:21) – IX2 D8 ee ff 4 EOR opr,X IX1 E8 ff 3 EOR ,X IX F8 2 EOR opr,SP SP1 9EE8 ff 4 EOR opr,SP SP2 9ED8 ee ff 5 INC opr M ← (M) + 1 DIR 3C dd 4 INCA A ← (A) + 1 INH 4C 1 INCX X ← (X) + 1 INH 5C 1 Increment (cid:21) – – (cid:21) (cid:21) – INC opr,X M ← (M) + 1 IX1 6C ff 4 INC ,X M ← (M) + 1 IX 7C 3 INC opr,SP M ← (M) + 1 SP1 9E6C ff 5 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 94 Freescale Semiconductor

Instruction Set Summary Table 7-1. Instruction Set Summary (Sheet 4 of 6) SFoourrmce Operation Description oEnf fCeCctR dressde code erand cles V H I N Z C do p p y AM O O C JMP opr DIR BC dd 2 JMP opr EXT CC hh ll 3 JMP opr,X Jump PC ← Jump Address – – – – – – IX2 DC ee ff 4 JMP opr,X IX1 EC ff 3 JMP ,X IX FC 2 JSR opr DIR BD dd 4 PC ← (PC) + n (n = 1, 2, or 3) JSR opr EXT CD hh ll 5 Push (PCL); SP ← (SP) – 1 JSR opr,X Jump to Subroutine – – – – – – IX2 DD ee ff 6 Push (PCH); SP ← (SP) – 1 JSR opr,X IX1 ED ff 5 PC ← Unconditional Address JSR ,X IX FD 4 LDA #opr IMM A6 ii 2 LDA opr DIR B6 dd 3 LDA opr EXT C6 hh ll 4 LDA opr,X IX2 D6 ee ff 4 Load A from M A ← (M) 0 – – (cid:21) (cid:21) – LDA opr,X IX1 E6 ff 3 LDA ,X IX F6 2 LDA opr,SP SP1 9EE6 ff 4 LDA opr,SP SP2 9ED6 ee ff 5 LDHX #opr IMM 45 ii jj 3 Load H:X from M H:X ← (M:M + 1) 0 – – (cid:21) (cid:21) – LDHX opr DIR 55 dd 4 LDX #opr IMM AE ii 2 LDX opr DIR BE dd 3 LDX opr EXT CE hh ll 4 LDX opr,X IX2 DE ee ff 4 Load X from M X ← (M) 0 – – (cid:21) (cid:21) – LDX opr,X IX1 EE ff 3 LDX ,X IX FE 2 LDX opr,SP SP1 9EEE ff 4 LDX opr,SP SP2 9EDE ee ff 5 LSL opr DIR 38 dd 4 LSLA INH 48 1 LSLX Logical Shift Left C 0 (cid:21) – – (cid:21) (cid:21) (cid:21) INH 58 1 LSL opr,X (Same as ASL) IX1 68 ff 4 LSL ,X b7 b0 IX 78 3 LSL opr,SP SP1 9E68 ff 5 LSR opr DIR 34 dd 4 LSRA INH 44 1 LSRX Logical Shift Right 0 C (cid:21) – – 0 (cid:21) (cid:21) INH 54 1 LSR opr,X IX1 64 ff 4 LSR ,X b7 b0 IX 74 3 LSR opr,SP SP1 9E64 ff 5 MOV opr,opr DD 4E dd dd 5 (M) ← (M) MOV opr,X+ Destination Source DIX+ 5E dd 4 Move 0 – – (cid:21) (cid:21) – MOV #opr,opr IMD 6E ii dd 4 H:X ← (H:X) + 1 (IX+D, DIX+) MOV X+,opr IX+D 7E dd 4 MUL Unsigned multiply X:A ← (X) × (A) – 0 – – – 0 INH 42 5 NEG opr DIR 30 dd 4 M ← –(M) = $00 – (M) NEGA INH 40 1 A ← –(A) = $00 – (A) NEGX INH 50 1 Negate (Two’s Complement) X ← –(X) = $00 – (X) (cid:21) – – (cid:21) (cid:21) (cid:21) NEG opr,X IX1 60 ff 4 M ← –(M) = $00 – (M) NEG ,X IX 70 3 M ← –(M) = $00 – (M) NEG opr,SP SP1 9E60 ff 5 NOP No Operation None – – – – – – INH 9D 1 NSA Nibble Swap A A ← (A[3:0]:A[7:4]) – – – – – – INH 62 3 ORA #opr IMM AA ii 2 ORA opr DIR BA dd 3 ORA opr EXT CA hh ll 4 ORA opr,X IX2 DA ee ff 4 Inclusive OR A and M A ← (A) | (M) 0 – – (cid:21) (cid:21) – ORA opr,X IX1 EA ff 3 ORA ,X IX FA 2 ORA opr,SP SP1 9EEA ff 4 ORA opr,SP SP2 9EDA ee ff 5 PSHA Push A onto Stack Push (A); SP ← (SP) – 1 – – – – – – INH 87 2 PSHH Push H onto Stack Push (H); SP ← (SP) – 1 – – – – – – INH 8B 2 PSHX Push X onto Stack Push (X); SP ← (SP) – 1 – – – – – – INH 89 2 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 95

Central Processor Unit (CPU) Table 7-1. Instruction Set Summary (Sheet 5 of 6) SFoourrmce Operation Description oEnf fCeCctR dressde code erand cles V H I N Z C do p p y AM O O C PULA Pull A from Stack SP ← (SP + 1); Pull (A) – – – – – – INH 86 2 PULH Pull H from Stack SP ← (SP + 1); Pull (H) – – – – – – INH 8A 2 PULX Pull X from Stack SP ← (SP + 1); Pull (X) – – – – – – INH 88 2 ROL opr DIR 39 dd 4 ROLA INH 49 1 ROLX INH 59 1 Rotate Left through Carry C (cid:21) – – (cid:21) (cid:21) (cid:21) ROL opr,X IX1 69 ff 4 ROL ,X b7 b0 IX 79 3 ROL opr,SP SP1 9E69 ff 5 ROR opr DIR 36 dd 4 RORA INH 46 1 RORX Rotate Right through Carry C (cid:21) – – (cid:21) (cid:21) (cid:21) INH 56 1 ROR opr,X IX1 66 ff 4 ROR ,X b7 b0 IX 76 3 ROR opr,SP SP1 9E66 ff 5 RSP Reset Stack Pointer SP ← $FF – – – – – – INH 9C 1 SP ← (SP) + 1; Pull (CCR) SP ← (SP) + 1; Pull (A) RTI Return from Interrupt SP ← (SP) + 1; Pull (X) (cid:21) (cid:21) (cid:21) (cid:21) (cid:21) (cid:21) INH 80 7 SP ← (SP) + 1; Pull (PCH) SP ← (SP) + 1; Pull (PCL) SP ← SP + 1; Pull (PCH) RTS Return from Subroutine – – – – – – INH 81 4 SP ← SP + 1; Pull (PCL) SBC #opr IMM A2 ii 2 SBC opr DIR B2 dd 3 SBC opr EXT C2 hh ll 4 SBC opr,X IX2 D2 ee ff 4 Subtract with Carry A ← (A) – (M) – (C) (cid:21) – – (cid:21) (cid:21) (cid:21) SBC opr,X IX1 E2 ff 3 SBC ,X IX F2 2 SBC opr,SP SP1 9EE2 ff 4 SBC opr,SP SP2 9ED2 ee ff 5 SEC Set Carry Bit C ← 1 – – – – – 1 INH 99 1 SEI Set Interrupt Mask I ← 1 – – 1 – – – INH 9B 2 STA opr DIR B7 dd 3 STA opr EXT C7 hh ll 4 STA opr,X IX2 D7 ee ff 4 STA opr,X Store A in M M ← (A) 0 – – (cid:21) (cid:21) – IX1 E7 ff 3 STA ,X IX F7 2 STA opr,SP SP1 9EE7 ff 4 STA opr,SP SP2 9ED7 ee ff 5 STHX opr Store H:X in M (M:M + 1) ← (H:X) 0 – – (cid:21) (cid:21) – DIR 35 dd 4 Enable Interrupts, Stop Processing, STOP I ← 0; Stop Processing – – 0 – – – INH 8E 1 Refer to MCU Documentation STX opr DIR BF dd 3 STX opr EXT CF hh ll 4 STX opr,X IX2 DF ee ff 4 STX opr,X Store X in M M ← (X) 0 – – (cid:21) (cid:21) – IX1 EF ff 3 STX ,X IX FF 2 STX opr,SP SP1 9EEF ff 4 STX opr,SP SP2 9EDF ee ff 5 SUB #opr IMM A0 ii 2 SUB opr DIR B0 dd 3 SUB opr EXT C0 hh ll 4 SUB opr,X IX2 D0 ee ff 4 Subtract A ← (A) – (M) (cid:21) – – (cid:21) (cid:21) (cid:21) SUB opr,X IX1 E0 ff 3 SUB ,X IX F0 2 SUB opr,SP SP1 9EE0 ff 4 SUB opr,SP SP2 9ED0 ee ff 5 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 96 Freescale Semiconductor

Opcode Map Table 7-1. Instruction Set Summary (Sheet 6 of 6) SFoourrmce Operation Description oEnf fCeCctR dressde code erand cles V H I N Z C do p p y AM O O C PC ← (PC) + 1; Push (PCL) SP ← (SP) – 1; Push (PCH) SP ← (SP) – 1; Push (X) SP ← (SP) – 1; Push (A) SWI Software Interrupt – – 1 – – – INH 83 9 SP ← (SP) – 1; Push (CCR) SP ← (SP) – 1; I ← 1 PCH ← Interrupt Vector High Byte PCL ← Interrupt Vector Low Byte TAP Transfer A to CCR CCR ← (A) (cid:21) (cid:21) (cid:21) (cid:21) (cid:21) (cid:21) INH 84 2 TAX Transfer A to X X ← (A) – – – – – – INH 97 1 TPA Transfer CCR to A A ← (CCR) – – – – – – INH 85 1 TST opr DIR 3D dd 3 TSTA INH 4D 1 TSTX INH 5D 1 Test for Negative or Zero (A) – $00 or (X) – $00 or (M) – $00 0 – – (cid:21) (cid:21) – TST opr,X IX1 6D ff 3 TST ,X IX 7D 2 TST opr,SP SP1 9E6D ff 4 TSX Transfer SP to H:X H:X ← (SP) + 1 – – – – – – INH 95 2 TXA Transfer X to A A ← (X) – – – – – – INH 9F 1 TXS Transfer H:X to SP (SP) ← (H:X) – 1 – – – – – – INH 94 2 I bit ← 0; Inhibit CPU clocking WAIT Enable Interrupts; Wait for Interrupt – – 0 – – – INH 8F 1 until interrupted A Accumulator n Any bit C Carry/borrow bit opr Operand (one or two bytes) CCR Condition code register PC Program counter dd Direct address of operand PCH Program counter high byte dd rr Direct address of operand and relative offset of branch instruction PCL Program counter low byte DD Direct to direct addressing mode REL Relative addressing mode DIR Direct addressing mode rel Relative program counter offset byte DIX+ Direct to indexed with post increment addressing mode rr Relative program counter offset byte ee ff High and low bytes of offset in indexed, 16-bit offset addressing SP1 Stack pointer, 8-bit offset addressing mode EXT Extended addressing mode SP2 Stack pointer 16-bit offset addressing mode ff Offset byte in indexed, 8-bit offset addressing SP Stack pointer H Half-carry bit U Undefined H Index register high byte V Overflow bit hh ll High and low bytes of operand address in extended addressing X Index register low byte I Interrupt mask Z Zero bit ii Immediate operand byte & Logical AND IMD Immediate source to direct destination addressing mode | Logical OR IMM Immediate addressing mode ⊕ Logical EXCLUSIVE OR INH Inherent addressing mode ( ) Contents of IX Indexed, no offset addressing mode –( ) Negation (two’s complement) IX+ Indexed, no offset, post increment addressing mode # Immediate value IX+D Indexed with post increment to direct addressing mode « Sign extend IX1 Indexed, 8-bit offset addressing mode ← Loaded with IX1+ Indexed, 8-bit offset, post increment addressing mode ? If IX2 Indexed, 16-bit offset addressing mode : Concatenated with M Memory location (cid:21) Set or cleared N Negative bit — Not affected 7.8 Opcode Map See Table 7-2. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 97

9 C 8 Table 7-2. Opcode Map en tr Bit Manipulation Branch Read-Modify-Write Control Register/Memory a DIR DIR REL DIR INH INH IX1 SP1 IX INH INH IMM DIR EXT IX2 SP2 IX1 SP1 IX l P r MSB o 0 1 2 3 4 5 6 9E6 7 8 9 A B C D 9ED E 9EE F c LSB e s 5 4 3 4 1 1 4 5 3 7 3 2 3 4 4 5 3 4 2 s 0 BRSET0 BSET0 BRA NEG NEGA NEGX NEG NEG NEG RTI BGE SUB SUB SUB SUB SUB SUB SUB SUB or 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 2 REL 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX U 5 4 3 5 4 4 5 6 4 4 3 2 3 4 4 5 3 4 2 n 1 B3RCDLRIR0 2BCLDRIR0 2BRRNEL 3CBEDQIR 3CBEIMQAM 3CBEIMQXM 3CBIXE1Q+ 4CBESQP1 2CBEIXQ+ 1RTINSH 2 BLRTEL 2CMIMPM 2CMDPIR 3CMEPXT 3CMIXP2 4CMSPP2 2CMIXP1 3CMSPP1 1CMIXP it (C 5 4 3 5 7 3 2 3 2 3 4 4 5 3 4 2 P 2 BRSET1 BSET1 BHI MUL DIV NSA DAA BGT SBC SBC SBC SBC SBC SBC SBC SBC U 3 DIR 2 DIR 2 REL 1 INH 1 INH 1 INH 1 INH 2 REL 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX ) 5 4 3 4 1 1 4 5 3 9 3 2 3 4 4 5 3 4 2 M 3 BRCLR1 BCLR1 BLS COM COMA COMX COM COM COM SWI BLE CPX CPX CPX CPX CPX CPX CPX CPX C 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 2 REL 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX 6 8 5 4 3 4 1 1 4 5 3 2 2 2 3 4 4 5 3 4 2 H 4 BRSET2 BSET2 BCC LSR LSRA LSRX LSR LSR LSR TAP TXS AND AND AND AND AND AND AND AND C 9 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 1 INH 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX 0 5 4 3 4 3 4 3 4 1 2 2 3 4 4 5 3 4 2 8G 5 BRCLR2 BCLR2 BCS STHX LDHX LDHX CPHX CPHX TPA TSX BIT BIT BIT BIT BIT BIT BIT BIT Z 3 DIR 2 DIR 2 REL 2 DIR 3 IMM 2 DIR 3 IMM 2 DIR 1 INH 1 INH 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX 1 5 4 3 4 1 1 4 5 3 2 2 3 4 4 5 3 4 2 6 (cid:129) 6 BRSET3 BSET3 BNE ROR RORA RORX ROR ROR ROR PULA LDA LDA LDA LDA LDA LDA LDA LDA M 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX C 5 4 3 4 1 1 4 5 3 2 1 2 3 4 4 5 3 4 2 6 7 BRCLR3 BCLR3 BEQ ASR ASRA ASRX ASR ASR ASR PSHA TAX AIS STA STA STA STA STA STA STA 8 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 1 INH 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX H C 5 4 3 4 1 1 4 5 3 2 1 2 3 4 4 5 3 4 2 9 8 BRSET4 BSET4 BHCC LSL LSLA LSLX LSL LSL LSL PULX CLC EOR EOR EOR EOR EOR EOR EOR EOR 0 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 1 INH 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX 8 G 5 4 3 4 1 1 4 5 3 2 1 2 3 4 4 5 3 4 2 Z 9 BRCLR4 BCLR4 BHCS ROL ROLA ROLX ROL ROL ROL PSHX SEC ADC ADC ADC ADC ADC ADC ADC ADC 8 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 1 INH 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX D 5 4 3 4 1 1 4 5 3 2 2 2 3 4 4 5 3 4 2 a ta S A 3BRSDEITR5 2BSEDTIR5 2 BPRLEL 2DEDCIR 1DECINAH 1DECINXH 2DEIXC1 3DESCP1 1DEIXC 1PUILNHH 1 CLINIH 2ORIMAM 2ORDAIR 3OREAXT 3ORIXA2 4ORSAP2 2ORIXA1 3ORSAP1 1ORIXA h 5 4 3 5 3 3 5 6 4 2 2 2 3 4 4 5 3 4 2 e B BRCLR5 BCLR5 BMI DBNZ DBNZA DBNZX DBNZ DBNZ DBNZ PSHH SEI ADD ADD ADD ADD ADD ADD ADD ADD et, R 3 D5IR 2 D4IR 2 R3EL 3 D4IR 2 I1NH 2 I1NH 3 I4X1 4 S5P1 2 I3X 1 I1NH 1 I1NH 2 IMM 2 D2IR 3 E3XT 3 I4X2 4 SP2 2 I3X1 3 SP1 1 I2X e C BRSET6 BSET6 BMC INC INCA INCX INC INC INC CLRH RSP JMP JMP JMP JMP JMP v 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 1 INH 2 DIR 3 EXT 3 IX2 2 IX1 1 IX . 4 5 4 3 3 1 1 3 4 2 1 4 4 5 6 5 4 D BRCLR6 BCLR6 BMS TST TSTA TSTX TST TST TST NOP BSR JSR JSR JSR JSR JSR 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 2 REL 2 DIR 3 EXT 3 IX2 2 IX1 1 IX 5 4 3 5 4 4 4 1 2 3 4 4 5 3 4 2 E BRSET7 BSET7 BIL MOV MOV MOV MOV STOP * LDX LDX LDX LDX LDX LDX LDX LDX F 3 DIR 2 DIR 2 REL 3 DD 2 DIX+ 3 IMD 2 IX+D 1 INH 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX re 5 4 3 3 1 1 3 4 2 1 1 2 3 4 4 5 3 4 2 e F BRCLR7 BCLR7 BIH CLR CLRA CLRX CLR CLR CLR WAIT TXA AIX STX STX STX STX STX STX STX sc 3 DIR 2 DIR 2 REL 2 DIR 1 INH 1 INH 2 IX1 3 SP1 1 IX 1 INH 1 INH 2 IMM 2 DIR 3 EXT 3 IX2 4 SP2 2 IX1 3 SP1 1 IX a le S INH Inherent REL Relative SP1 Stack Pointer, 8-Bit Offset MSB e IMM Immediate IX Indexed, No Offset SP2 Stack Pointer, 16-Bit Offset 0 High Byte of Opcode in Hexadecimal m DIR Direct IX1 Indexed, 8-Bit Offset IX+ Indexed, No Offset with LSB ic EXT Extended IX2 Indexed, 16-Bit Offset Post Increment 5 Cycles ond DIXD+DDInidreecxte-dD-iDreircetct DIMIXD+DImirmecetd-Iinadtee-xDeidrect IX1+ PInodsetx Iendc,r e1m-Beyntet Offset with Low Byte of Opcode in Hexadecimal 0 3BRSDEITR0 ONupmcobdeer Mofn Beymteosn i/c Addressing Mode u *Pre-byte for stack pointer indexed instructions c to r

Chapter 8 External Interrupt (IRQ) 8.1 Introduction The IRQ (external interrupt) module provides a maskable interrupt input. 8.2 Features Features of the IRQ module include: (cid:129) A dedicated external interrupt pin (IRQ) (cid:129) IRQ interrupt control bits (cid:129) Hysteresis buffer (cid:129) Programmable edge-only or edge and level interrupt sensitivity (cid:129) Automatic interrupt acknowledge (cid:129) Internal pullup resistor 8.3 Functional Description A logic 0 applied to the external interrupt pin can latch a central processor unit (CPU) interrupt request. Figure 8-1 shows the structure of the IRQ module. Interrupt signals on the IRQ pin are latched into the IRQ latch. An interrupt latch remains set until one of the following actions occurs: (cid:129) Vector fetch — A vector fetch automatically generates an interrupt acknowledge signal that clears the latch that caused the vector fetch. (cid:129) Software clear — Software can clear an interrupt latch by writing to the appropriate acknowledge bit in the interrupt status and control register (INTSCR). Writing a logic 1 to the ACK bit clears the IRQ latch. (cid:129) Reset — A reset automatically clears the interrupt latch. The external interrupt pin is falling-edge triggered and is software-configurable to be either falling-edge or falling-edge and low-level triggered. The MODE bit in the INTSCR controls the triggering sensitivity of the IRQ pin. When an interrupt pin is edge-triggered only, the interrupt remains set until a vector fetch, software clear, or reset occurs. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 99

External Interrupt (IRQ) RESET ACK TO CPU FOR S VECTOR U BIL/BIH B FETCH SS DECODER INSTRUCTIONS E R DD VDD A RNAL IPNUTLELRUNPAL VDD IRQF E DEVICE T CLR IN D Q IRQ SYNCHRONIZER INTERRUPT IRQ CK REQUEST IMASK MODE HIGH TO MODE VOLTAGE SELECT DETECT LOGIC Figure 8-1. IRQ Module Block Diagram When an interrupt pin is both falling-edge and low-level triggered, the interrupt remains set until both of these events occur: (cid:129) Vector fetch or software clear (cid:129) Return of the interrupt pin to logic 1 The vector fetch or software clear may occur before or after the interrupt pin returns to logic 1. As long as the pin is low, the interrupt request remains pending. A reset will clear the latch and the MODE control bit, thereby clearing the interrupt even if the pin stays low. When set, the IMASK bit in the INTSCR mask all external interrupt requests. A latched interrupt request is not presented to the interrupt priority logic unless the IMASK bit is clear. NOTE The interrupt mask (I) in the condition code register (CCR) masks all interrupt requests, including external interrupt requests. Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 IRQF 0 IRQ Status and Control IMASK MODE $001D Register (INTSCR) Write: ACK See page 102. Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 8-2. IRQ I/O Register Summary MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 100 Freescale Semiconductor

IRQ Pin 8.4 IRQ Pin A logic 0 on the IRQ pin can latch an interrupt request into the IRQ latch. A vector fetch, software clear, or reset clears the IRQ latch. If the MODE bit is set, the IRQ pin is both falling-edge-sensitive and low-level-sensitive. With MODE set, both of the following actions must occur to clear IRQ: (cid:129) Vector fetch or software clear — A vector fetch generates an interrupt acknowledge signal to clear the latch. Software may generate the interrupt acknowledge signal by writing a logic 1 to the ACK bit in the interrupt status and control register (INTSCR). The ACK bit is useful in applications that poll the IRQ pin and require software to clear the IRQ latch. Writing to the ACK bit prior to leaving an interrupt service routine can also prevent spurious interrupts due to noise. Setting ACK does not affect subsequent transitions on the IRQ pin. A falling edge that occurs after writing to the ACK bit another interrupt request. If the IRQ mask bit, IMASK, is clear, the CPU loads the program counter with the vector address at locations $FFFA and $FFFB. (cid:129) Return of the IRQ pin to logic 1 — As long as the IRQ pin is at logic 0, IRQ remains active. The vector fetch or software clear and the return of the IRQ pin to logic 1 may occur in any order. The interrupt request remains pending as long as the IRQ pin is at logic 0. A reset will clear the latch and the MODE control bit, thereby clearing the interrupt even if the pin stays low. If the MODE bit is clear, the IRQ pin is falling-edge-sensitive only. With MODE clear, a vector fetch or software clear immediately clears the IRQ latch. The IRQF bit in the INTSCR register can be used to check for pending interrupts. The IRQF bit is not affected by the IMASK bit, which makes it useful in applications where polling is preferred. Use the BIH or BIL instruction to read the logic level on the IRQ pin. NOTE When using the level-sensitive interrupt trigger, avoid false interrupts by masking interrupt requests in the interrupt routine. 8.5 IRQ Module During Break Interrupts The BCFE bit in the SIM break flag control register (SBFCR) enables software to clear the latch during the break state. See Chapter 20 Development Support. To allow software to clear the IRQ latch during a break interrupt, write a logic 1 to the BCFE bit. If a latch is cleared during the break state, it remains cleared when the MCU exits the break state. To protect CPU interrupt flags during the break state, write a logic 0 to the BCFE bit. With BCFE at logic 0 (its default state), writing to the ACK bit in the IRQ status and control register during the break state has no effect on the IRQ interrupt flags. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 101

External Interrupt (IRQ) 8.6 IRQ Status and Control Register The IRQ status and control register (INTSCR) controls and monitors operation of the IRQ module. The INTSCR: (cid:129) Shows the state of the IRQ flag (cid:129) Clears the IRQ latch (cid:129) Masks IRQ interrupt request (cid:129) Controls triggering sensitivity of the IRQ interrupt pin Address: $001D Bit 7 6 5 4 3 2 1 Bit 0 Read: IRQF 0 IMASK MODE Write: ACK Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 8-3. IRQ Status and Control Register (INTSCR) IRQF — IRQ Flag Bit This read-only status bit is high when the IRQ interrupt is pending. 1 = IRQ interrupt pending 0 = IRQ interrupt not pending ACK — IRQ Interrupt Request Acknowledge Bit Writing a logic 1 to this write-only bit clears the IRQ latch. ACK always reads as logic 0. Reset clears ACK. IMASK — IRQ Interrupt Mask Bit Writing a logic 1 to this read/write bit disables IRQ interrupt requests. Reset clears IMASK. 1 = IRQ interrupt requests disabled 0 = IRQ interrupt requests enabled MODE — IRQ Edge/Level Select Bit This read/write bit controls the triggering sensitivity of the IRQ pin. Reset clears MODE. 1 = IRQ interrupt requests on falling edges and low levels 0 = IRQ interrupt requests on falling edges only MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 102 Freescale Semiconductor

Chapter 9 Keyboard Interrupt Module (KBI) 9.1 Introduction The keyboard interrupt module (KBI) provides eight independently maskable external interrupts which are accessible via PTA0–PTA7. When a port pin is enabled for keyboard interrupt function, an internal pullup device is also enabled on the pin. 9.2 Features Features include: (cid:129) Eight keyboard interrupt pins with separate keyboard interrupt enable bits and one keyboard interrupt mask (cid:129) Hysteresis buffers (cid:129) Programmable edge-only or edge- and level- interrupt sensitivity (cid:129) Exit from low-power modes (cid:129) I/O (input/output) port bit(s) software configurable with pullup device(s) if configured as input port bit(s) 9.3 Functional Description Writing to the KBIE7–KBIE0 bits in the keyboard interrupt enable register independently enables or disables each port A pin as a keyboard interrupt pin. Enabling a keyboard interrupt pin also enables its internal pullup device. A logic 0 applied to an enabled keyboard interrupt pin latches a keyboard interrupt request. A keyboard interrupt is latched when one or more keyboard pins goes low after all were high. The MODEK bit in the keyboard status and control register controls the triggering mode of the keyboard interrupt. (cid:129) If the keyboard interrupt is edge-sensitive only, a falling edge on a keyboard pin does not latch an interrupt request if another keyboard pin is already low. To prevent losing an interrupt request on one pin because another pin is still low, software can disable the latter pin while it is low. (cid:129) If the keyboard interrupt is falling edge- and low-level sensitive, an interrupt request is present as long as any keyboard interrupt pin is low and the pin is keyboard interrupt enabled. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 103

Keyboard Interrupt Module (KBI) INTERNAL BUS M68HC08 CPU REGCISPTUERS ARITUHNMIET T(AICL/ULO)GIC PROGRAMMMOADBULLEE TIMEBASE DDRA PORTA PPTTAA70//KKBBDD70–(1) PTB7/AD7 SINGLE BREAKPOINT CONTROL AND STATUS REGISTERS — 64 BYTES PTB6/AD6 BREAK MODULE PTB5/AD5 USER FLASH — 15,872 BYTES LOWD-UVAOLL TVAOGLETA INGHEIBIT DDRB PORTB PPTTBB43//AADD43 MODULE PTB2/AD2 USER RAM — 1024 BYTES PTB1/AD1 8-BIT KEYBOARD PTB0/AD0 MONITOR ROM — 350 BYTES INTERRUPT MODULE PTC6(1) PTC5(1) FLASH PROGRAMMING ROUTINES ROM — 406 BYTES 2-CHANNEL TIMER USER FLASH VECTOR SPACE — 44 BYTES INTERFACE MODULE 1 DDRC PORTC PPPTTTCCC432(((111))),,, (((222))) 2-CHANNEL TIMER INTERFACE MODULE 2 PTC1/CANRX(1), (2) CLOCK GENERATOR MODULE PTC0/CAN (1), (2) TX OSC1 1–8 MHz OSCILLATOR ENHANCED SERIAL OSC2 COMUNICATIONS PTD7/T2CH1(1) PHASE LOCKED LOOP INTERFACE MODULE PTD6/T2CH0(1) CGMXFC PTD5/T1CH1(1) RST(3) SYSTEM INTEGRATION COPMRPOUPTEERRL YO MPEORDAUTLIENG DDRD PORTD PPPTTTDDD243///MTS1POCSSHCI(0K1()(11)) MODULE SERIAL PERIPHERAL PTD1/MISO(1) INTERFACE MODULE PTD0/SS(1) IRQ(3) SINGLE EXTERNAL INTERRUPT MODULE PTE5–PTE2 VVDDAD//VVREFH 10-CBOITN AVNEARLTOEGR- TMOO-DDUIGLIETAL MONITOR MODULE DDRE PORTE PPTTEE10//RTxxDD DDAD REFL MEMORY MAP MODULE POWER-ON RESET MODULE SECURITY CONFIGURATION MODULE VDD REGISTER 1–2 VSS POWER MODULE V DDA V MONITOR MODE ENTRY SSA MSCAN08 MODULE MODULE 1. Ports are software configurable with pullup device if input port. 2. Higher current drive port pins 3. Pin contains integrated pullup device Figure 9-1. Block Diagram Highlighting KBI Block and Pins MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 104 Freescale Semiconductor

Functional Description INTERNAL BUS VECTOR FETCH DECODER ACKK RESET KBD0 V DD KEYF . CLR TO PULLUP ENABLE D Q SYNCHRONIZER . CK KB0IE . KEYBOARD INTERRUPT IMASKK REQUEST KBD7 MODEK TO PULLUP ENABLE KB7IE Figure 9-2. Keyboard Module Block Diagram Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Keyboard Status Read: 0 0 0 0 KEYF 0 IMASKK MODEK and Control Register $001A Write: ACKK (INTKBSCR) See page 107. Reset: 0 0 0 0 0 0 0 0 Read: Keyboard Interrupt Enable KBIE7 KBIE6 KBIE5 KBIE4 KBIE3 KBIE2 KBIE1 KBIE0 $001B Register (INTKBIER) Write: See page 108. Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 9-3. I/O Register Summary If the MODEK bit is set, the keyboard interrupt pins are both falling edge- and low-level sensitive, and both of the following actions must occur to clear a keyboard interrupt request: (cid:129) Vector fetch or software clear — A vector fetch generates an interrupt acknowledge signal to clear the interrupt request. Software may generate the interrupt acknowledge signal by writing a logic 1 to the ACKK bit in the keyboard status and control register (INTKBSCR). The ACKK bit is useful in applications that poll the keyboard interrupt pins and require software to clear the keyboard interrupt request. Writing to the ACKK bit prior to leaving an interrupt service routine can also prevent spurious interrupts due to noise. Setting ACKK does not affect subsequent transitions on the keyboard interrupt pins. A falling edge that occurs after writing to the ACKK bit latches another interrupt request. If the keyboard interrupt mask bit, IMASKK, is clear, the CPU loads the program counter with the vector address at locations $FFE0 and $FFE1. (cid:129) Return of all enabled keyboard interrupt pins to logic 1 — As long as any enabled keyboard interrupt pin is at logic 0, the keyboard interrupt remains set. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 105

Keyboard Interrupt Module (KBI) The vector fetch or software clear and the return of all enabled keyboard interrupt pins to logic 1 may occur in any order. If the MODEK bit is clear, the keyboard interrupt pin is falling-edge-sensitive only. With MODEK clear, a vector fetch or software clear immediately clears the keyboard interrupt request. Reset clears the keyboard interrupt request and the MODEK bit, clearing the interrupt request even if a keyboard interrupt pin stays at logic 0. The keyboard flag bit (KEYF) in the keyboard status and control register can be used to see if a pending interrupt exists. The KEYF bit is not affected by the keyboard interrupt mask bit (IMASKK) which makes it useful in applications where polling is preferred. To determine the logic level on a keyboard interrupt pin, use the data direction register to configure the pin as an input and read the data register. NOTE Setting a keyboard interrupt enable bit (KBIEx) forces the corresponding keyboard interrupt pin to be an input, overriding the data direction register. However, the data direction register bit must be a logic 0 for software to read the pin. 9.4 Keyboard Initialization When a keyboard interrupt pin is enabled, it takes time for the internal pullup to reach a logic 1. Therefore, a false interrupt can occur as soon as the pin is enabled. To prevent a false interrupt on keyboard initialization: 1. Mask keyboard interrupts by setting the IMASKK bit in the keyboard status and control register. 2. Enable the KBI pins by setting the appropriate KBIEx bits in the keyboard interrupt enable register. 3. Write to the ACKK bit in the keyboard status and control register to clear any false interrupts. 4. Clear the IMASKK bit. An interrupt signal on an edge-triggered pin can be acknowledged immediately after enabling the pin. An interrupt signal on an edge- and level-triggered interrupt pin must be acknowledged after a delay that depends on the external load. Another way to avoid a false interrupt: 1. Configure the keyboard pins as outputs by setting the appropriate DDRA bits in data direction register A. 2. Write logic 1s to the appropriate port A data register bits. 3. Enable the KBI pins by setting the appropriate KBIEx bits in the keyboard interrupt enable register. 9.5 Low-Power Modes The WAIT and STOP instructions put the microcontroller unit (MCU) in low power-consumption standby modes. 9.5.1 Wait Mode The keyboard module remains active in wait mode. Clearing the IMASKK bit in the keyboard status and control register enables keyboard interrupt requests to bring the MCU out of wait mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 106 Freescale Semiconductor

Keyboard Module During Break Interrupts 9.5.2 Stop Mode The keyboard module remains active in stop mode. Clearing the IMASKK bit in the keyboard status and control register enables keyboard interrupt requests to bring the MCU out of stop mode. 9.6 Keyboard Module During Break Interrupts The system integration module (SIM) controls whether the keyboard interrupt latch can be cleared during the break state. The BCFE bit in the break flag control register (BFCR) enables software to clear status bits during the break state. To allow software to clear the keyboard interrupt latch during a break interrupt, write a logic 1 to the BCFE bit. If a latch is cleared during the break state, it remains cleared when the MCU exits the break state. To protect the latch during the break state, write a logic 0 to the BCFE bit. With BCFE at logic 0 (its default state), writing to the keyboard acknowledge bit (ACKK) in the keyboard status and control register during the break state has no effect. See 9.7.1 Keyboard Status and Control Register. 9.7 I/O Registers These registers control and monitor operation of the keyboard module: (cid:129) Keyboard status and control register (INTKBSCR) (cid:129) Keyboard interrupt enable register (INTKBIER) 9.7.1 Keyboard Status and Control Register The keyboard status and control register: (cid:129) Flags keyboard interrupt requests (cid:129) Acknowledges keyboard interrupt requests (cid:129) Masks keyboard interrupt requests (cid:129) Controls keyboard interrupt triggering sensitivity Address: $001A Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 KEYF 0 IMASKK MODEK Write: ACKK Reset: 0 0 0 0 0 0 0 0 =Unimplemented Figure 9-4. Keyboard Status and Control Register (INTKBSCR) Bits 7–4 — Not used These read-only bits always read as logic 0s. KEYF — Keyboard Flag Bit This read-only bit is set when a keyboard interrupt is pending. Reset clears the KEYF bit. 1 = Keyboard interrupt pending 0 = No keyboard interrupt pending MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 107

Keyboard Interrupt Module (KBI) ACKK — Keyboard Acknowledge Bit Writing a logic 1 to this write-only bit clears the keyboard interrupt request. ACKK always reads as logic 0. Reset clears ACKK. IMASKK — Keyboard Interrupt Mask Bit Writing a logic 1 to this read/write bit prevents the output of the keyboard interrupt mask from generating interrupt requests. Reset clears the IMASKK bit. 1 = Keyboard interrupt requests masked 0 = Keyboard interrupt requests not masked MODEK — Keyboard Triggering Sensitivity Bit This read/write bit controls the triggering sensitivity of the keyboard interrupt pins. Reset clears MODEK. 1 = Keyboard interrupt requests on falling edges and low levels 0 = Keyboard interrupt requests on falling edges only 9.7.2 Keyboard Interrupt Enable Register The keyboard interrupt enable register enables or disables each port A pin to operate as a keyboard interrupt pin. Address: $001B Bit 7 6 5 4 3 2 1 Bit 0 Read: KBIE7 KBIE6 KBIE5 KBIE4 KBIE3 KBIE2 KBIE1 KBIE0 Write: Reset: 0 0 0 0 0 0 0 0 Figure 9-5. Keyboard Interrupt Enable Register (INTKBIER) KBIE7–KBIE0 — Keyboard Interrupt Enable Bits Each of these read/write bits enables the corresponding keyboard interrupt pin to latch interrupt requests. Reset clears the keyboard interrupt enable register. 1 = PTAx pin enabled as keyboard interrupt pin 0 = PTAx pin not enabled as keyboard interrupt pin MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 108 Freescale Semiconductor

Chapter 10 Low-Power Modes 10.1 Introduction The microcontroller (MCU) may enter two low-power modes: wait mode and stop mode. They are common to all HC08 MCUs and are entered through instruction execution. This section describes how each module acts in the low-power modes. 10.1.1 Wait Mode The WAIT instruction puts the MCU in a low-power standby mode in which the central processor unit (CPU) clock is disabled but the bus clock continues to run. Power consumption can be further reduced by disabling the low-voltage inhibit (LVI) module through bits in the CONFIG1 register. See Chapter 5 Configuration Register (CONFIG). 10.1.2 Stop Mode Stop mode is entered when a STOP instruction is executed. The CPU clock is disabled and the bus clock is disabled if the OSCENINSTOP bit in the CONFIG2 register is at a logic 0. See Chapter 5 Configuration Register (CONFIG). 10.2 Analog-to-Digital Converter (ADC) 10.2.1 Wait Mode The analog-to-digital converter (ADC) continues normal operation during wait mode. Any enabled CPU interrupt request from the ADC can bring the MCU out of wait mode. If the ADC is not required to bring the MCU out of wait mode, power down the ADC by setting ADCH4–ADCH0 bits in the ADC status and control register before executing the WAIT instruction. 10.2.2 Stop Mode The ADC module is inactive after the execution of a STOP instruction. Any pending conversion is aborted. ADC conversions resume when the MCU exits stop mode after an external interrupt. Allow one conversion cycle to stabilize the analog circuitry. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 109

Low-Power Modes 10.3 Break Module (BRK) 10.3.1 Wait Mode If enabled, the break (BRK) module is active in wait mode. In the break routine, the user can subtract one from the return address on the stack if the SBSW bit in the break status register is set. 10.3.2 Stop Mode The break module is inactive in stop mode. The STOP instruction does not affect break module register states. 10.4 Central Processor Unit (CPU) 10.4.1 Wait Mode The WAIT instruction: (cid:129) Clears the interrupt mask (I bit) in the condition code register, enabling interrupts. After exit from wait mode by interrupt, the I bit remains clear. After exit by reset, the I bit is set. (cid:129) Disables the CPU clock 10.4.2 Stop Mode The STOP instruction: (cid:129) Clears the interrupt mask (I bit) in the condition code register, enabling external interrupts. After exit from stop mode by external interrupt, the I bit remains clear. After exit by reset, the I bit is set. (cid:129) Disables the CPU clock After exiting stop mode, the CPU clock begins running after the oscillator stabilization delay. 10.5 Clock Generator Module (CGM) 10.5.1 Wait Mode The clock generator module (CGM) remains active in wait mode. Before entering wait mode, software can disengage and turn off the PLL by clearing the BCS and PLLON bits in the PLL control register (PCTL). Less power-sensitive applications can disengage the PLL without turning it off. Applications that require the PLL to wake the MCU from wait mode also can deselect the PLL output without turning off the PLL. 10.5.2 Stop Mode If the OSCSTOPEN bit in the CONFIG register is cleared (default), then the STOP instruction disables the CGM (oscillator and phase-locked loop) and holds low all CGM outputs (CGMXCLK, CGMOUT, and CGMINT). If the OSCSTOPEN bit in the CONFIG register is set, then the phase locked loop is shut off, but the oscillator will continue to operate in stop mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 110 Freescale Semiconductor

Computer Operating Properly Module (COP) 10.6 Computer Operating Properly Module (COP) 10.6.1 Wait Mode The COP remains active during wait mode. If COP is enabled, a reset will occur at COP timeout. 10.6.2 Stop Mode Stop mode turns off the COPCLK input to the COP and clears the COP prescaler. Service the COP immediately before entering or after exiting stop mode to ensure a full COP timeout period after entering or exiting stop mode. The STOP bit in the CONFIG1 register enables the STOP instruction. To prevent inadvertently turning off the COP with a STOP instruction, disable the STOP instruction by clearing the STOP bit. 10.7 External Interrupt Module (IRQ) 10.7.1 Wait Mode The external interrupt (IRQ) module remains active in wait mode. Clearing the IMASK1 bit in the IRQ status and control register enables IRQ CPU interrupt requests to bring the MCU out of wait mode. 10.7.2 Stop Mode The IRQ module remains active in stop mode. Clearing the IMASK1 bit in the IRQ status and control register enables IRQ CPU interrupt requests to bring the MCU out of stop mode. 10.8 Keyboard Interrupt Module (KBI) 10.8.1 Wait Mode The keyboard interrupt (KBI) module remains active in wait mode. Clearing the IMASKK bit in the keyboard status and control register enables keyboard interrupt requests to bring the MCU out of wait mode. 10.8.2 Stop Mode The keyboard module remains active in stop mode. Clearing the IMASKK bit in the keyboard status and control register enables keyboard interrupt requests to bring the MCU out of stop mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 111

Low-Power Modes 10.9 Low-Voltage Inhibit Module (LVI) 10.9.1 Wait Mode If enabled, the low-voltage inhibit (LVI) module remains active in wait mode. If enabled to generate resets, the LVI module can generate a reset and bring the MCU out of wait mode. 10.9.2 Stop Mode If enabled, the LVI module remains active in stop mode. If enabled to generate resets, the LVI module can generate a reset and bring the MCU out of stop mode. 10.10 Enhanced Serial Communications Interface Module (ESCI) 10.10.1 Wait Mode The enhanced serial communications interface (ESCI), or SCI module for short, module remains active in wait mode. Any enabled CPU interrupt request from the SCI module can bring the MCU out of wait mode. If SCI module functions are not required during wait mode, reduce power consumption by disabling the module before executing the WAIT instruction. 10.10.2 Stop Mode The SCI module is inactive in stop mode. The STOP instruction does not affect SCI register states. SCI module operation resumes after the MCU exits stop mode. Because the internal clock is inactive during stop mode, entering stop mode during an SCI transmission or reception results in invalid data. 10.11 Serial Peripheral Interface Module (SPI) 10.11.1 Wait Mode The serial peripheral interface (SPI) module remains active in wait mode. Any enabled CPU interrupt request from the SPI module can bring the MCU out of wait mode. If SPI module functions are not required during wait mode, reduce power consumption by disabling the SPI module before executing the WAIT instruction. 10.11.2 Stop Mode The SPI module is inactive in stop mode. The STOP instruction does not affect SPI register states. SPI operation resumes after an external interrupt. If stop mode is exited by reset, any transfer in progress is aborted, and the SPI is reset. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 112 Freescale Semiconductor

Timer Interface Module (TIM1 and TIM2) 10.12 Timer Interface Module (TIM1 and TIM2) 10.12.1 Wait Mode The timer interface modules (TIM) remain active in wait mode. Any enabled CPU interrupt request from the TIM can bring the MCU out of wait mode. If TIM functions are not required during wait mode, reduce power consumption by stopping the TIM before executing the WAIT instruction. 10.12.2 Stop Mode The TIM is inactive in stop mode. The STOP instruction does not affect register states or the state of the TIM counter. TIM operation resumes when the MCU exits stop mode after an external interrupt. 10.13 Timebase Module (TBM) 10.13.1 Wait Mode The timebase module (TBM) remains active after execution of the WAIT instruction. In wait mode, the timebase register is not accessible by the CPU. If the timebase functions are not required during wait mode, reduce the power consumption by stopping the timebase before enabling the WAIT instruction. 10.13.2 Stop Mode The timebase module may remain active after execution of the STOP instruction if the oscillator has been enabled to operate during stop mode through the OSCENINSTOP bit in the CONFIG2 register. The timebase module can be used in this mode to generate a periodic wakeup from stop mode. If the oscillator has not been enabled to operate in stop mode, the timebase module will not be active during stop mode. In stop mode, the timebase register is not accessible by the CPU. If the timebase functions are not required during stop mode, reduce the power consumption by stopping the timebase before enabling the STOP instruction. 10.14 MSCAN 10.14.1 Wait Mode The MSCAN module remains active after execution of the WAIT instruction. In wait mode, the MSCAN08 registers are not accessible by the CPU. If the MSCAN08 functions are not required during wait mode, reduce the power consumption by disabling the MSCAN08 module before enabling the WAIT instruction. 10.14.2 Stop Mode The MSCAN08 module is inactive in stop mode. The STOP instruction does not affect MSCAN08 register states. Because the internal clock is inactive during stop mode, entering stop mode during an MSCAN08 transmission or reception results in invalid data. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 113

Low-Power Modes 10.15 Exiting Wait Mode These events restart the CPU clock and load the program counter with the reset vector or with an interrupt vector: (cid:129) External reset — A logic 0 on the RST pin resets the MCU and loads the program counter with the contents of locations $FFFE and $FFFF. (cid:129) External interrupt — A high-to-low transition on an external interrupt pin (IRQ pin) loads the program counter with the contents of locations: $FFFA and $FFFB; IRQ pin. (cid:129) Break interrupt — In emulation mode, a break interrupt loads the program counter with the contents of $FFFC and $FFFD. (cid:129) Computer operating properly (COP) module reset — A timeout of the COP counter resets the MCU and loads the program counter with the contents of $FFFE and $FFFF. (cid:129) Low-voltage inhibit (LVI) module reset — A power supply voltage below the V voltage resets TRIPF the MCU and loads the program counter with the contents of locations $FFFE and $FFFF. (cid:129) Clock generator module (CGM) interrupt — A CPU interrupt request from the CGM loads the program counter with the contents of $FFF8 and $FFF9. (cid:129) Keyboard interrupt (KBI) module — A CPU interrupt request from the KBI module loads the program counter with the contents of $FFE0 and $FFE1. (cid:129) Timer 1 interface (TIM1) module interrupt — A CPU interrupt request from the TIM1 loads the program counter with the contents of: – $FFF2 and $FFF3; TIM1 overflow – $FFF4 and $FFF5; TIM1 channel 1 – $FFF6 and $FFF7; TIM1 channel 0 (cid:129) Timer 2 interface (TIM2) module interrupt — A CPU interrupt request from the TIM2 loads the program counter with the contents of: – $FFEC and $FFED; TIM2 overflow – $FFEE and $FFEF; TIM2 channel 1 – $FFF0 and $FFF1; TIM2 channel 0 (cid:129) Serial peripheral interface (SPI) module interrupt — A CPU interrupt request from the SPI loads the program counter with the contents of: – $FFE8 and $FFE9; SPI transmitter – $FFEA and $FFEB; SPI receiver (cid:129) Serial communications interface (SCI) module interrupt — A CPU interrupt request from the SCI loads the program counter with the contents of: – $FFE2 and $FFE3; SCI transmitter – $FFE4 and $FFE5; SCI receiver – $FFE6 and $FFE7; SCI receiver error (cid:129) Analog-to-digital converter (ADC) module interrupt — A CPU interrupt request from the ADC loads the program counter with the contents of: $FFDE and $FFDF; ADC conversion complete. (cid:129) Timebase module (TBM) interrupt — A CPU interrupt request from the TBM loads the program counter with the contents of: $FFDC and $FFDD; TBM interrupt. (cid:129) MSCAN module interrupt — A CPU interrupt request from the MSCAN08 loads the program counter with the contents of: – $FFD4 and $FFD5; MSCAN08 transmitter – $FFD6 and $FFD7; MSCAN08 receiver – $FFD8 and $FFD9; MSCAN08 error – $FFDA and $FFDB; MSCAN08 wakeup MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 114 Freescale Semiconductor

Exiting Stop Mode 10.16 Exiting Stop Mode These events restart the system clocks and load the program counter with the reset vector or with an interrupt vector: (cid:129) External reset — A logic 0 on the RST pin resets the MCU and loads the program counter with the contents of locations $FFFE and $FFFF. (cid:129) External interrupt — A high-to-low transition on an external interrupt pin loads the program counter with the contents of locations: – $FFFA and $FFFB; IRQ pin – $FFE0 and $FFE1; keyboard interrupt pins (cid:129) Low-voltage inhibit (LVI) reset — A power supply voltage below the LVI voltage resets the TRIPF MCU and loads the program counter with the contents of locations $FFFE and $FFFF. (cid:129) Timebase module (TBM) interrupt — A TBM interrupt loads the program counter with the contents of locations $FFDC and $FFDD when the timebase counter has rolled over. This allows the TBM to generate a periodic wakeup from stop mode. (cid:129) MSCAN08 interrupt — MSCAN08 bus activity can wake the MCU from CPU stop. However, until the oscillator starts up and synchronization is achieved the MSCAN08 will not respond to incoming data. Upon exit from stop mode, the system clocks begin running after an oscillator stabilization delay. A 12-bit stop recovery counter inhibits the system clocks for 4096 CGMXCLK cycles after the reset or external interrupt. The short stop recovery bit, SSREC, in the CONFIG1 register controls the oscillator stabilization delay during stop recovery. Setting SSREC reduces stop recovery time from 4096 CGMXCLK cycles to 32 CGMXCLK cycles. NOTE Use the full stop recovery time (SSREC = 0) in applications that use an external crystal. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 115

Low-Power Modes MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 116 Freescale Semiconductor

Chapter 11 Low-Voltage Inhibit (LVI) 11.1 Introduction This section describes the low-voltage inhibit (LVI) module, which monitors the voltage on the V pin DD and can force a reset when the V voltage falls below the LVI trip falling voltage, V . DD TRIPF 11.2 Features Features of the LVI module include: (cid:129) Programmable LVI reset (cid:129) Selectable LVI trip voltage (cid:129) Programmable stop mode operation 11.3 Functional Description Figure 11-1 shows the structure of the LVI module. The LVI is enabled out of reset. The LVI module contains a bandgap reference circuit and comparator. Clearing the LVI power disable bit, LVIPWRD, enables the LVI to monitor V voltage. Clearing the LVI reset disable bit, LVIRSTD, enables the LVI DD module to generate a reset when V falls below a voltage, V . Setting the LVI enable in stop mode DD TRIPF bit, LVISTOP, enables the LVI to operate in stop mode. Setting the LVI 5-V or 3-V trip point bit, LVI5OR3, enables the trip point voltage, V , to be configured for 5-V operation. Clearing the LVI5OR3 bit TRIPF enables the trip point voltage, V , to be configured for 3-V operation. The actual trip points are shown TRIPF in Chapter 21 Electrical Specifications. NOTE After a power-on reset (POR) the LVI’s default mode of operation is 3 V. If a 5-V system is used, the user must set the LVI5OR3 bit to raise the trip point to 5-V operation. Note that this must be done after every power-on reset since the default will revert back to 3-V mode after each power-on reset. If the V supply is below the 5-V mode trip voltage but above the DD 3-V mode trip voltage when POR is released, the part will operate because V defaults to 3-V mode after a POR. So, in a 5-V system care must be TRIPF taken to ensure that V is above the 5-V mode trip voltage after POR is DD released. If the user requires 5-V mode and sets the LVI5OR3 bit after a power-on reset while the V supply is not above the V for 5-V mode, the DD TRIPR microcontroller unit (MCU) will immediately go into reset. The LVI in this case will hold the part in reset until either V goes above the rising 5-V trip DD point, V , which will release reset or V decreases to approximately 0 TRIPR DD V which will re-trigger the power-on reset and reset the trip point to 3-V operation. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 117

Low-Voltage Inhibit (LVI) LVISTOP, LVIPWRD, LVI5OR3, and LVIRSTD are in the configuration register (CONFIG1). See Figure 5-2. Configuration Register 1 (CONFIG1) for details of the LVI’s configuration bits. Once an LVI reset occurs, the MCU remains in reset until V rises above a voltage, V , which causes the MCU DD TRIPR to exit reset. See 16.3.2.5 Low-Voltage Inhibit (LVI) Reset for details of the interaction between the SIM and the LVI. The output of the comparator controls the state of the LVIOUT flag in the LVI status register (LVISR). An LVI reset also drives the RST pin low to provide low-voltage protection to external peripheral devices. V DD STOP INSTRUCTION LVISTOP FROM CONFIG1 FROM CONFIG1 LVIRSTD LVIPWRD FROM CONFIG LOW V VDD > LVITrip = 0 LVI RESET DD DETECTOR V ≤ LVI = 1 DD Trip LVIOUT LVI5OR3 FROM CONFIG1 Figure 11-1. LVI Module Block Diagram Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: LVIOUT 0 0 0 0 0 0 0 LVI Status Register $FE0C (LVISR) Write: See page 119. Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 11-2. LVI I/O Register Summary 11.3.1 Polled LVI Operation In applications that can operate at V levels below the V level, software can monitor V by polling DD TRIPF DD the LVIOUT bit. In the configuration register, the LVIPWRD bit must be at logic 0 to enable the LVI module, and the LVIRSTD bit must be at logic 1 to disable LVI resets. 11.3.2 Forced Reset Operation In applications that require V to remain above the V level, enabling LVI resets allows the LVI DD TRIPF module to reset the MCU when V falls below the V level. In the configuration register, the DD TRIPF LVIPWRD and LVIRSTD bits must be at logic 0 to enable the LVI module and to enable LVI resets. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 118 Freescale Semiconductor

LVI Status Register 11.3.3 Voltage Hysteresis Protection Once the LVI has triggered (by having V fall below V ), the LVI will maintain a reset condition until DD TRIPF V rises above the rising trip point voltage, V . This prevents a condition in which the MCU is DD TRIPR continually entering and exiting reset if V is approximately equal to V . V is greater than DD TRIPF TRIPR V by the hysteresis voltage, V . TRIPF HYS 11.3.4 LVI Trip Selection The LVI5OR3 bit in the configuration register selects whether the LVI is configured for 5-V or 3-V protection. NOTE The microcontroller is guaranteed to operate at a minimum supply voltage. The trip point (V [5 V] or V [3 V]) may be lower than this. See TRIPF TRIPF Chapter 21 Electrical Specifications for the actual trip point voltages. 11.4 LVI Status Register The LVI status register (LVISR) indicates if the V voltage was detected below the V level. DD TRIPF Address: $FE0C Bit 7 6 5 4 3 2 1 Bit 0 Read: LVIOUT 0 0 0 0 0 0 0 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 11-3. LVI Status Register (LVISR) LVIOUT — LVI Output Bit This read-only flag becomes set when the V voltage falls below the V trip voltage (see DD TRIPF Table 11-1). Reset clears the LVIOUT bit. Table 11-1. LVIOUT Bit Indication VDD LVIOUT VDD > VTRIPR 0 VDD < VTRIPF 1 VTRIPF < VDD < VTRIPR Previous value 11.5 LVI Interrupts The LVI module does not generate interrupt requests. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 119

Low-Voltage Inhibit (LVI) 11.6 Low-Power Modes The STOP and WAIT instructions put the MCU in low power-consumption standby modes. 11.6.1 Wait Mode If enabled, the LVI module remains active in wait mode. If enabled to generate resets, the LVI module can generate a reset and bring the MCU out of wait mode. 11.6.2 Stop Mode If enabled in stop mode (LVISTOP set), the LVI module remains active in stop mode. If enabled to generate resets, the LVI module can generate a reset and bring the MCU out of stop mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 120 Freescale Semiconductor

Chapter 12 MSCAN08 Controller (MSCAN08) 12.1 Introduction The MSCAN08 is the specific implementation of the MSCAN concept targeted for the M68HC08 Microcontroller Family. The module is a communication controller implementing the CAN 2.0 A/B protocol as defined in the BOSCH specification dated September, 1991. The CAN protocol was primarily, but not exclusively, designed to be used as a vehicle serial data bus, meeting the specific requirements of this field: real-time processing, reliable operation in the electromagnetic interference (EMI) environment of a vehicle, cost-effectiveness, and required bandwidth. MSCAN08 utilizes an advanced buffer arrangement, resulting in a predictable real-time behavior, and simplifies the application software. 12.2 Features Basic features of the MSCAN08 are: (cid:129) MSCAN08 enable is software controlled by bit (MSCANEN) in configuration register (CONFIG2) (cid:129) Modular architecture (cid:129) Implementation of the CAN Protocol — Version 2.0A/B – Standard and extended data frames – 0–8 bytes data length. – Programmable bit rate up to 1 Mbps depending on the actual bit timing and the clock jitter of the phase-locked loop (PLL) (cid:129) Support for remote frames (cid:129) Double-buffered receive storage scheme (cid:129) Triple-buffered transmit storage scheme with internal prioritization using a “local priority” concept (cid:129) Flexible maskable identifier filter supports alternatively one full size extended identifier filter or two 16-bit filters or four 8-bit filters (cid:129) Programmable wakeup functionality with integrated low-pass filter (cid:129) Programmable loop-back mode supports self-test operation (cid:129) Separate signalling and interrupt capabilities for all CAN receiver and transmitter error states (warning, error passive, bus off) (cid:129) Programmable MSCAN08 clock source either CPU bus clock or crystal oscillator output (cid:129) Programmable link to timer interface module 1, channel 0, for time-stamping and network synchronization (cid:129) Low-power sleep mode MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 121

MSCAN08 Controller (MSCAN08) INTERNAL BUS M68HC08 CPU REGCISPTUERS ARITUHNMIET T(AICL/ULO)GIC PROGRAMMMOADBULLEE TIMEBASE DDRA PORTA PPTTAA70//KKBBDD70–(1) PTB7/AD7 SINGLE BREAKPOINT CONTROL AND STATUS REGISTERS — 64 BYTES PTB6/AD6 BREAK MODULE PTB5/AD5 USER FLASH — 15,872 BYTES LOWD-UVAOLL TVAOGLETA INGHEIBIT DDRB PORTB PPTTBB43//AADD43 MODULE PTB2/AD2 USER RAM — 1024 BYTES PTB1/AD1 8-BIT KEYBOARD PTB0/AD0 MONITOR ROM — 350 BYTES INTERRUPT MODULE PTC6(1) PTC5(1) FLASH PROGRAMMING ROUTINES ROM — 406 BYTES 2-CHANNEL TIMER USER FLASH VECTOR SPACE — 44 BYTES INTERFACE MODULE 1 DDRC PORTC PPPTTTCCC432(((111))),,, (((222))) 2-CHANNEL TIMER INTERFACE MODULE 2 PTC1/CANRX(1), (2) CLOCK GENERATOR MODULE PTC0/CAN (1), (2) TX OSC1 1–8 MHz OSCILLATOR ENHANCED SERIAL OSC2 COMUNICATIONS PTD7/T2CH1(1) PHASE LOCKED LOOP INTERFACE MODULE PTD6/T2CH0(1) CGMXFC PTD5/T1CH1(1) RST(3) SYSTEM INTEGRATION COPMRPOUPTEERRL YO MPEORDAUTLIENG DDRD PORTD PPPTTTDDD243///MTS1POCSSHCI(0K1()(11)) MODULE SERIAL PERIPHERAL PTD1/MISO(1) INTERFACE MODULE PTD0/SS(1) IRQ(3) SINGLE EXTERNAL INTERRUPT MODULE PTE5–PTE2 VVDDAD//VVREFH 10-CBOITN AVNEARLTOEGR- TMOO-DDUIGLIETAL MONITOR MODULE DDRE PORTE PPTTEE10//RTxxDD DDAD REFL MEMORY MAP MODULE POWER-ON RESET MODULE SECURITY CONFIGURATION MODULE VDD REGISTER 1–2 VSS POWER MODULE V DDA V MONITOR MODE ENTRY SSA MSCAN08 MODULE MODULE 1. Ports are software configurable with pullup device if input port. 2. Higher current drive port pins 3. Pin contains integrated pullup device Figure 12-1. Block Diagram Highlighting MSCAN08 Block and Pins 12.3 External Pins The MSCAN08 uses two external pins, one input (CAN ) and one output (CAN ). The CAN output RX TX TX pin represents the logic level on the CAN: 0 is for a dominant state, and 1 is for a recessive state. A typical CAN system with MSCAN08 is shown in Figure 12-2. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 122 Freescale Semiconductor

Message Storage CAN STATION 1 CAN NODE 1 CAN NODE 2 CAN NODE N MCU CAN CONTROLLER (MSCAN08) CAN CAN TX RX TRANSCEIVER CAN_H CAN_L CAN BUS Figure 12-2. The CAN System Each CAN station is connected physically to the CAN bus lines through a transceiver chip. The transceiver is capable of driving the large current needed for the CAN and has current protection against defected CAN or defected stations. 12.4 Message Storage MSCAN08 facilitates a sophisticated message storage system which addresses the requirements of a broad range of network applications. 12.4.1 Background Modern application layer software is built under two fundamental assumptions: 1. Any CAN node is able to send out a stream of scheduled messages without releasing the bus between two messages. Such nodes will arbitrate for the bus right after sending the previous message and will only release the bus in case of lost arbitration. 2. The internal message queue within any CAN node is organized as such that the highest priority message will be sent out first if more than one message is ready to be sent. Above behavior cannot be achieved with a single transmit buffer. That buffer must be reloaded right after the previous message has been sent. This loading process lasts a definite amount of time and has to be completed within the inter-frame sequence (IFS) to be able to send an uninterrupted stream of messages. Even if this is feasible for limited CAN bus speeds, it requires that the CPU reacts with short latencies to the transmit interrupt. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 123

MSCAN08 Controller (MSCAN08) A double buffer scheme would de-couple the re-loading of the transmit buffers from the actual message being sent and as such reduces the reactiveness requirements on the CPU. Problems may arise if the sending of a message would be finished just while the CPU re-loads the second buffer. In that case, no buffer would then be ready for transmission and the bus would be released. At least three transmit buffers are required to meet the first of the above requirements under all circumstances. The MSCAN08 has three transmit buffers. The second requirement calls for some sort of internal prioritization which the MSCAN08 implements with the “local priority” concept described in 12.4.2 Receive Structures. 12.4.2 Receive Structures The received messages are stored in a 2-stage input first in first out (FIFO). The two message buffers are mapped using a "ping pong" arrangement into a single memory area (see Figure 12-3). While the background receive buffer (RxBG) is exclusively associated to the MSCAN08, the foreground receive buffer (RxFG) is addressable by the central processor unit (CPU08). This scheme simplifies the handler software, because only one address area is applicable for the receive process. Both buffers have a size of 13 bytes to store the CAN control bits, the identifier (standard or extended), and the data content. For details, see 12.12 Programmer’s Model of Message Storage. The receiver full flag (RXF) in the MSCAN08 receiver flag register (CRFLG), signals the status of the foreground receive buffer. When the buffer contains a correctly received message with matching identifier, this flag is set. See 12.13.5 MSCAN08 Receiver Flag Register (CRFLG) On reception, each message is checked to see if it passes the filter (for details see 12.5 Identifier Acceptance Filter) and in parallel is written into RxBG. The MSCAN08 copies the content of RxBG into RxFG(1), sets the RXF flag, and generates a receive interrupt to the CPU(2). The user’s receive handler has to read the received message from RxFG and to reset the RXF flag to acknowledge the interrupt and to release the foreground buffer. A new message which can follow immediately after the IFS field of the CAN frame, is received into RxBG. The overwriting of the background buffer is independent of the identifier filter function. When the MSCAN08 module is transmitting, the MSCAN08 receives its own messages into the background receive buffer, RxBG. It does NOT overwrite RxFG, generate a receive interrupt or acknowledge its own messages on the CAN bus. The exception to this rule is in loop-back mode (see 12.13.2 MSCAN08 Module Control Register 1), where the MSCAN08 treats its own messages exactly like all other incoming messages. The MSCAN08 receives its own transmitted messages in the event that it loses arbitration. If arbitration is lost, the MSCAN08 must be prepared to become the receiver. An overrun condition occurs when both the foreground and the background receive message buffers are filled with correctly received messages with accepted identifiers and another message is correctly received from the bus with an accepted identifier. The latter message will be discarded and an error interrupt with overrun indication will be generated if enabled. The MSCAN08 is still able to transmit messages with both receive message buffers filled, but all incoming messages are discarded. 1. Only if the RXF flag is not set. 2. The receive interrupt will occur only if not masked. A polling scheme can be applied on RXF also. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 124 Freescale Semiconductor

Message Storage MSCAN08 CPU08 I BUS RxBG RxFG RXF Tx0 TXE PRIO Tx1 TXE PRIO Tx2 TXE PRIO Figure 12-3. User Model for Message Buffer Organization 12.4.3 Transmit Structures The MSCAN08 has a triple transmit buffer scheme to allow multiple messages to be set up in advance and to achieve an optimized real-time performance. The three buffers are arranged as shown in Figure 12-3. All three buffers have a 13-byte data structure similar to the outline of the receive buffers (see 12.12 Programmer’s Model of Message Storage). An additional transmit buffer priority register (TBPR) contains an 8-bit “local priority” field (PRIO) (see 12.12.5 Transmit Buffer Priority Registers). MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 125

MSCAN08 Controller (MSCAN08) To transmit a message, the CPU08 has to identify an available transmit buffer which is indicated by a set transmit buffer empty (TXE) flag in the MSCAN08 transmitter flag register (CTFLG) (see 12.13.7 MSCAN08 Transmitter Flag Register). The CPU08 then stores the identifier, the control bits and the data content into one of the transmit buffers. Finally, the buffer has to be flagged ready for transmission by clearing the TXE flag. The MSCAN08 then will schedule the message for transmission and will signal the successful transmission of the buffer by setting the TXE flag. A transmit interrupt is generated(1) when TXE is set and can be used to drive the application software to re-load the buffer. In case more than one buffer is scheduled for transmission when the CAN bus becomes available for arbitration, the MSCAN08 uses the local priority setting of the three buffers for prioritization. For this purpose, every transmit buffer has an 8-bit local priority field (PRIO). The application software sets this field when the message is set up. The local priority reflects the priority of this particular message relative to the set of messages being emitted from this node. The lowest binary value of the PRIO field is defined as the highest priority. The internal scheduling process takes place whenever the MSCAN08 arbitrates for the bus. This is also the case after the occurrence of a transmission error. When a high priority message is scheduled by the application software, it may become necessary to abort a lower priority message being set up in one of the three transmit buffers. As messages that are already under transmission cannot be aborted, the user has to request the abort by setting the corresponding abort request flag (ABTRQ) in the transmission control register (CTCR). The MSCAN08 will then grant the request, if possible, by setting the corresponding abort request acknowledge (ABTAK) and the TXE flag in order to release the buffer and by generating a transmit interrupt. The transmit interrupt handler software can tell from the setting of the ABTAK flag whether the message was actually aborted (ABTAK = 1) or sent (ABTAK = 0). 12.5 Identifier Acceptance Filter The identifier acceptance registers (CIDAR0–CIDAR3) define the acceptance patterns of the standard or extended identifier (ID10–ID0 or ID28–ID0). Any of these bits can be marked ‘don’t care’ in the identifier mask registers (CIDMR0–CIDMR3). A filter hit is indicated to the application on software by a set RXF (receive buffer full flag, see 12.13.5 MSCAN08 Receiver Flag Register (CRFLG)) and two bits in the identifier acceptance control register (see 12.13.9 MSCAN08 Identifier Acceptance Control Register). These identifier hit flags (IDHIT1 and IDHIT0) clearly identify the filter section that caused the acceptance. They simplify the application software’s task to identify the cause of the receiver interrupt. In case that more than one hit occurs (two or more filters match) the lower hit has priority. A very flexible programmable generic identifier acceptance filter has been introduced to reduce the CPU interrupt loading. The filter is programmable to operate in four different modes: 1. Single identifier acceptance filter, each to be applied to a) the full 29 bits of the extended identifier and to the following bits of the CAN frame: RTR, IDE, SRR or b) the 11 bits of the standard identifier plus the RTR and IDE bits of CAN 2.0A/B messages. This mode implements a single filter for a full length CAN 2.0B compliant extended identifier. Figure 12-4 shows how the 32-bit filter bank (CIDAR0-3, CIDMR0-3) produces a filter 0 hit. 1. The transmit interrupt will occur only if not masked. A polling scheme can be applied on TXE also. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 126 Freescale Semiconductor

Identifier Acceptance Filter 2. Two identifier acceptance filters, each to be applied to: a. The 14 most significant bits of the extended identifier plus the SRR and the IDE bits of CAN2.0B messages, or b. The 11 bits of the identifier plus the RTR and IDE bits of CAN 2.0A/B messages. Figure 12-5 shows how the 32-bit filter bank (CIDAR0–CIDAR3 and CIDMR0–CIDMR3) produces filter 0 and 1 hits. 3. Four identifier acceptance filters, each to be applied to the first eight bits of the identifier. This mode implements four independent filters for the first eight bits of a CAN 2.0A/B compliant standard identifier. Figure 12-6 shows how the 32-bit filter bank (CIDAR0–CIDAR3 and CIDMR0–CIDMR3) produces filter 0 to 3 hits. 4. Closed filter. No CAN message will be copied into the foreground buffer RxFG, and the RXF flag will never be set. ID28 IDR0 ID21 ID20 IDR1 ID15 ID14 IDR2 ID7 ID6 IDR3 RTR ID10 IDR0 ID3 ID2 IDR1 IDE ID10 IDR2 ID3 ID10 IDR3 ID3 AM7 CIDMR0 AM0 AM7 CIDMR1 AM0 AM7 CIDMR2 AM0 AM7 CIDMR3 AM0 AC7 CIDAR0 AC0 AC7 CIDAR1 AC0 AC7 CIDAR2 AC0 AC7 CIDAR3 AC0 ID Accepted (Filter 0 Hit) Figure 12-4. Single 32-Bit Maskable Identifier Acceptance Filter ID28 IDR0 ID21 ID20 IDR1 ID15 ID14 IDR2 ID7 ID6 IDR3 RTR ID10 IDR0 ID3 ID2 IDR1 IDE ID10 IDR2 ID3 ID10 IDR3 ID3 AM7 CIDMR0 AM0 AM7 CIDMR1 AM0 AC7 CIDAR0 AC0 AC7 CIDAR1 AC0 ID ACCEPTED (FILTER 0 HIT) AM7 CIDMR2 AM0 AM7 CIDMR3 AM0 AC7 CIDAR2 AC0 AC7 CIDAR3 AC0 ID ACCEPTED (FILTER 1 HIT) Figure 12-5. Dual 16-Bit Maskable Acceptance Filters MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 127

MSCAN08 Controller (MSCAN08) ID28 IDR0 ID21 ID20 IDR1 ID15 ID14 IDR2 ID7 ID6 IDR3 RTR ID10 IDR0 ID3 ID2 IDR1 IDE ID10 IDR2 ID3 ID10 IDR3 ID3 AM7 CIDMR0 AM0 AC7 CIDAR0 AC0 ID ACCEPTED (FILTER 0 HIT) AM7 CIDMR1 AM0 AC7 CIDAR1 AC0 ID ACCEPTED (FILTER 1 HIT) AM7 CIDMR2 AM0 AC7 CIDAR2 AC0 ID ACCEPTED (FILTER 2 HIT) AM7 CIDMR3 AM0 AC7 CIDAR3 AC0 ID ACCEPTED (FILTER 3 HIT) Figure 12-6. Quadruple 8-Bit Maskable Acceptance Filters MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 128 Freescale Semiconductor

Interrupts 12.6 Interrupts The MSCAN08 supports four interrupt vectors mapped onto eleven different interrupt sources, any of which can be individually masked. For details, see 12.13.5 MSCAN08 Receiver Flag Register (CRFLG) through 12.13.8 MSCAN08 Transmitter Control Register. 1. Transmit Interrupt: At least one of the three transmit buffers is empty (not scheduled) and can be loaded to schedule a message for transmission. The TXE flags of the empty message buffers are set. 2. Receive Interrupt: A message has been received successfully and loaded into the foreground receive buffer. This interrupt will be emitted immediately after receiving the EOF symbol. The RXF flag is set. 3. Wakeup Interrupt: An activity on the CAN bus occurred during MSCAN08 internal sleep mode or power-down mode (provided SLPAK = WUPIE = 1). 4. Error Interrupt: An overrun, error, or warning condition occurred. The receiver flag register (CRFLG) will indicate one of the following conditions: – Overrun: An overrun condition as described in 12.4.2 Receive Structures, has occurred. – Receiver Warning: The receive error counter has reached the CPU warning limit of 96. – Transmitter Warning: The transmit error counter has reached the CPU warning limit of 96. – Receiver Error Passive: The receive error counter has exceeded the error passive limit of 127 and MSCAN08 has gone to error passive state. – Transmitter Error Passive: The transmit error counter has exceeded the error passive limit of 127 and MSCAN08 has gone to error passive state. – Bus Off: The transmit error counter has exceeded 255 and MSCAN08 has gone to bus off state. 12.6.1 Interrupt Acknowledge Interrupts are directly associated with one or more status flags in either the MSCAN08 receiver flag register (CRFLG) or the MSCAN08 transmitter flag register (CTFLG). Interrupts are pending as long as one of the corresponding flags is set. The flags in the above registers must be reset within the interrupt handler in order to handshake the interrupt. The flags are reset through writing a ‘1’ to the corresponding bit position. A flag cannot be cleared if the respective condition still prevails. NOTE Bit manipulation instructions (BSET) shall not be used to clear interrupt flags. 12.6.2 Interrupt Vectors The MSCAN08 supports four interrupt vectors as shown in Table 12-1. The vector addresses and the relative interrupt priority are dependent on the chip integration and to be defined. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 129

MSCAN08 Controller (MSCAN08) Table 12-1. MSCAN08 Interrupt Vector Addresses Local Global Function Source Mask Mask Wakeup WUPIF WUPIE RWRNIF RWRNIE TWRNIF TWRNIE RERRIF RERRIE Error interrupts TERRIF TERRIE BOFFIF BOFFIE I bit OVRIF OVRIE Receive RXF RXFIE TXE0 TXEIE0 Transmit TXE1 TXEIE1 TXE2 TXEIE2 12.7 Protocol Violation Protection The MSCAN08 will protect the user from accidentally violating the CAN protocol through programming errors. The protection logic implements the following features: (cid:129) The receive and transmit error counters cannot be written or otherwise manipulated. (cid:129) All registers which control the configuration of the MSCAN08 can not be modified while the MSCAN08 is on-line. The SFTRES bit in the MSCAN08 module control register (see 12.13.1 MSCAN08 Module Control Register 0) serves as a lock to protect the following registers: – MSCAN08 module control register 1 (CMCR1) – MSCAN08 bus timing register 0 and 1 (CBTR0 and CBTR1) – MSCAN08 identifier acceptance control register (CIDAC) – MSCAN08 identifier acceptance registers (CIDAR0–3) – MSCAN08 identifier mask registers (CIDMR0–3) (cid:129) The CAN pin is forced to recessive when the MSCAN08 is in any of the low-power modes. TX 12.8 Low-Power Modes In addition to normal mode, the MSCAN08 has three modes with reduced power consumption: sleep, soft reset, and power down. In sleep and soft reset mode, power consumption is reduced by stopping all clocks except those to access the registers. In power-down mode, all clocks are stopped and no power is consumed. The WAIT and STOP instructions put the MCU in low-power consumption stand-by modes. Table 12-2 summarizes the combinations of MSCAN08 and CPU modes. A particular combination of modes is entered for the given settings of the bits SLPAK and SFTRES. For all modes, an MSCAN08 wakeup interrupt can occur only if SLPAK = WUPIE = 1. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 130 Freescale Semiconductor

Low-Power Modes . Table 12-2. MSCAN08 versus CPU Operating Modes CPU Mode MSCAN08 Mode STOP WAIT or RUN SLPAK = X(1) Power Down SFTRES = X SLPAK = 1 Sleep SFTRES = 0 SLPAK = 0 Soft Reset SFTRES = 1 SLPAK = 0 Normal SFTRES = 0 1. ‘X’ means don’t care. 12.8.1 MSCAN08 Sleep Mode The CPU can request the MSCAN08 to enter the low-power mode by asserting the SLPRQ bit in the module configuration register (see Figure 12-7). The time when the MSCAN08 enters sleep mode depends on its activity: (cid:129) If it is transmitting, it continues to transmit until there is no more message to be transmitted, and then goes into sleep mode (cid:129) If it is receiving, it waits for the end of this message and then goes into sleep mode (cid:129) If it is neither transmitting or receiving, it will immediately go into sleep mode NOTE The application software must avoid setting up a transmission (by clearing or more TXE flags) and immediately request sleep mode (by setting SLPRQ). It then depends on the exact sequence of operations whether MSCAN08 starts transmitting or goes into sleep mode directly. During sleep mode, the SLPAK flag is set. The application software should use SLPAK as a handshake indication for the request (SLPRQ) to go into sleep mode. When in sleep mode, the MSCAN08 stops its internal clocks. However, clocks to allow register accesses still run. If the MSCAN08 is in bus-off state, it stops counting the 128*11 consecutive recessive bits due to the stopped clocks. The CAN pin stays in TX recessive state. If RXF = 1, the message can be read and RXF can be cleared. Copying of RxGB into RxFG doesn’t take place while in sleep mode. It is possible to access the transmit buffers and to clear the TXE flags. No message abort takes place while in sleep mode. The MSCAN08 leaves sleep mode (wakes-up) when: (cid:129) Bus activity occurs, or (cid:129) The MCU clears the SLPRQ bit, or (cid:129) The MCU sets the SFTRES bit NOTE The MCU cannot clear the SLPRQ bit before the MSCAN08 is in sleep mode (SLPAK=1). MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 131

MSCAN08 Controller (MSCAN08) MSCAN08 RUNNING MCU SLPRQ = 0 or MSCAN08 SLPAK = 0 MCU MSCAN08 SLEEPING SLEEP REQUEST SLPRQ = 1 SLPRQ = 1 SLPAK = 1 SLPAK = 0 MSCAN08 Figure 12-7. Sleep Request/Acknowledge Cycle After wakeup, the MSCAN08 waits for 11 consecutive recessive bits to synchronize to the bus. As a consequence, if the MSCAN08 is woken-up by a CAN frame, this frame is not received. The receive message buffers (RxFG and RxBG) contain messages if they were received before sleep mode was entered. All pending actions are executed upon wakeup: copying of RxBG into RxFG, message aborts and message transmissions. If the MSCAN08 is still in bus-off state after sleep mode was left, it continues counting the 128*11 consecutive recessive bits. 12.8.2 MSCAN08 Soft Reset Mode In soft reset mode, the MSCAN08 is stopped. Registers can still be accessed. This mode is used to initialize the module configuration, bit timing and the CAN message filter. See 12.13.1 MSCAN08 Module Control Register 0 for a complete description of the soft reset mode. When setting the SFTRES bit, the MSCAN08 immediately stops all ongoing transmissions and receptions, potentially causing CAN protocol violations. NOTE The user is responsible to take care that the MSCAN08 is not active when soft reset mode is entered. The recommended procedure is to bring the MSCAN08 into sleep mode before the SFTRES bit is set. 12.8.3 MSCAN08 Power-Down Mode The MSCAN08 is in power-down mode when the CPU is in stop mode. When entering the power-down mode, the MSCAN08 immediately stops all ongoing transmissions and receptions, potentially causing CAN protocol violations. NOTE The user is responsible to take care that the MSCAN08 is not active when power-down mode is entered. The recommended procedure is to bring the MSCAN08 into sleep mode before the STOP instruction is executed. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 132 Freescale Semiconductor

Timer Link To protect the CAN bus system from fatal consequences resulting from violations of the above rule, the MSCAN08 drives the CAN pin into recessive state. TX In power-down mode, no registers can be accessed. MSCAN08 bus activity can wake the MCU from CPU stop/MSCAN08 power-down mode. However, until the oscillator starts up and synchronization is achieved the MSCAN08 will not respond to incoming data. 12.8.4 CPU Wait Mode The MSCAN08 module remains active during CPU wait mode. The MSCAN08 will stay synchronized to the CAN bus and generates transmit, receive, and error interrupts to the CPU, if enabled. Any such interrupt will bring the MCU out of wait mode. 12.8.5 Programmable Wakeup Function The MSCAN08 can be programmed to apply a low-pass filter function to the CAN input line while in RX internal sleep mode (see information on control bit WUPM in 12.13.2 MSCAN08 Module Control Register 1). This feature can be used to protect the MSCAN08 from wakeup due to short glitches on the CAN bus lines. Such glitches can result from electromagnetic inference within noisy environments. 12.9 Timer Link The MSCAN08 will generate a timer signal whenever a valid frame has been received. Because the CAN specification defines a frame to be valid if no errors occurred before the EOF field has been transmitted successfully, the timer signal will be generated right after the EOF. A pulse of one bit time is generated. As the MSCAN08 receiver engine also receives the frames being sent by itself, a timer signal also will be generated after a successful transmission. The previously described timer signal can be routed into the on-chip timer interface module (TIM). This signal is connected to channel 0 of timer interface module 1 (TIM1) under the control of the timer link enable (TLNKEN) bit in CMCR0. After the timer has been programmed to capture rising edge events, it can be used under software control to generate 16-bit time stamps which can be stored with the received message. 12.10 Clock System Figure 12-8 shows the structure of the MSCAN08 clock generation circuitry and its interaction with the clock generation module (CGM). With this flexible clocking scheme the MSCAN08 is able to handle CAN bus rates ranging from 10 kbps up to 1 Mbps. The clock source bit (CLKSRC) in the MSCAN08 module control register (CMCR1) (see 12.13.1 MSCAN08 Module Control Register 0) defines whether the MSCAN08 is connected to the output of the crystal oscillator or to the PLL output. The clock source has to be chosen such that the tight oscillator tolerance requirements (up to 0.4%) of the CAN protocol are met. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 133

MSCAN08 Controller (MSCAN08) CGMXCLK OSC ÷ 2 CGMOUT (TO SIM) BCS PLL ÷ 2 CGM MSCAN08 (2 * BUS FREQUENCY) ÷ 2 MSCANCLK PRESCALER (1 ... 64) CLKSRC Figure 12-8. Clocking Scheme NOTE If the system clock is generated from a PLL, it is recommended to select the crystal clock source rather than the system clock source due to jitter considerations, especially at faster CAN bus rates. A programmable prescaler is used to generate out of the MSCAN08 clock the time quanta (Tq) clock. A time quantum is the atomic unit of time handled by the MSCAN08. f MSCANCLK f = Tq Presc value A bit time is subdivided into three segments(1) (see Figure 12-9): (cid:129) SYNC_SEG: This segment has a fixed length of one time quantum. Signal edges are expected to happen within this section. (cid:129) Time segment 1: This segment includes the PROP_SEG and the PHASE_SEG1 of the CAN standard. It can be programmed by setting the parameter TSEG1 to consist of 4 to 16 time quanta. (cid:129) Time segment 2: This segment represents PHASE_SEG2 of the CAN standard. It can be programmed by setting the TSEG2 parameter to be 2 to 8 time quanta long. f Tq Bit rate = No. of time quanta 1. For further explanation of the underlying concepts please refer to ISO/DIS 11 519-1, Section 10.3. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 134 Freescale Semiconductor

Clock System The synchronization jump width (SJW) can be programmed in a range of 1 to 4 time quanta by setting the SJW parameter. The above parameters can be set by programming the bus timing registers, CBTR0 and CBTR1. See 12.13.3 MSCAN08 Bus Timing Register 0 and 12.13.4 MSCAN08 Bus Timing Register 1. NOTE It is the user’s responsibility to make sure that the bit timing settings are in compliance with the CAN standard, Table 12-8 gives an overview on the CAN conforming segment settings and the related parameter values. NRZ SIGNAL SYNC TIME SEGMENT 1 TIME SEG. 2 _SEG (PROP_SEG + PHASE_SEG1) (PHASE_SEG2) 1 4 ... 16 2 ... 8 8... 25 TIME QUANTA = 1 BIT TIME SAMPLE POINT (SINGLE OR TRIPLE SAMPLING) Figure 12-9. Segments Within the Bit Time Table 12-3. Time Segment Syntax SYNC_SEG System expects transitions to occur on the bus during this period. Transmit point A node in transmit mode will transfer a new value to the CAN bus at this point. A node in receive mode will sample the bus at this point. If the three samples Sample point per bit option is selected then this point marks the position of the third sample. Table 12-4. CAN Standard Compliant Bit Time Segment Settings Time Time Synchronized TSEG1 TSEG2 SJW Segment 1 Segment 2 Jump Width 5 .. 10 4 .. 9 2 1 1 .. 2 0 .. 1 4 .. 11 3 .. 10 3 2 1 .. 3 0 .. 2 5 .. 12 4 .. 11 4 3 1 .. 4 0 .. 3 6 .. 13 5 .. 12 5 4 1 .. 4 0 .. 3 7 .. 14 6 .. 13 6 5 1 .. 4 0 .. 3 8 .. 15 7 .. 14 7 6 1 .. 4 0 .. 3 9 .. 16 8 .. 15 8 7 1 .. 4 0 .. 3 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 135

MSCAN08 Controller (MSCAN08) 12.11 Memory Map The MSCAN08 occupies 128 bytes in the CPU08 memory space. The absolute mapping is implementation dependent with the base address being a multiple of 128. $0500 CONTROL REGISTERS $0508 9 BYTES $0509 RESERVED $050D 5 BYTES $050E ERROR COUNTERS $050F 2 BYTES $0510 IDENTIFIER FILTER $0517 8 BYTES $0518 RESERVED $053F 40 BYTES $0540 RECEIVE BUFFER $054F $0550 TRANSMIT BUFFER 0 $055F $0560 TRANSMIT BUFFER 1 $056F $0570 TRANSMIT BUFFER 2 $057F Figure 12-10. MSCAN08 Memory Map MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 136 Freescale Semiconductor

Programmer’s Model of Message Storage 12.12 Programmer’s Model of Message Storage This section details the organization of the receive and transmit message buffers and the associated control registers. For reasons of programmer interface simplification, the receive and transmit message buffers have the same outline. Each message buffer allocates 16 bytes in the memory map containing a 13-byte data structure. An additional transmit buffer priority register (TBPR) is defined for the transmit buffers. Addr(1) Register Name $05b0 IDENTIFIER REGISTER 0 $05b1 IDENTIFIER REGISTER 1 $05b2 IDENTIFIER REGISTER 2 $05b3 IDENTIFIER REGISTER 3 $05b4 DATA SEGMENT REGISTER 0 $05b5 DATA SEGMENT REGISTER 1 $05b6 DATA SEGMENT REGISTER 2 $05b7 DATA SEGMENT REGISTER 3 $05b8 DATA SEGMENT REGISTER 4 $05b9 DATA SEGMENT REGISTER 5 $05bA DATA SEGMENT REGISTER 6 $05bB DATA SEGMENT REGISTER 7 $05bC DATA LENGTH REGISTER $05bD TRANSMIT BUFFER PRIORITY REGISTER(2) $05bE UNUSED $05bF UNUSED 1. Where b equals the following: b=4 for receive buffer b=5 for transmit buffer 0 b=6 for transmit buffer 1 b=7 for transmit buffer 2 2. Not applicable for receive buffers Figure 12-11. Message Buffer Organization 12.12.1 Message Buffer Outline Figure 12-12 shows the common 13-byte data structure of receive and transmit buffers for extended identifiers. The mapping of standard identifiers into the IDR registers is shown in Figure 12-13. All bits of the 13-byte data structure are undefined out of reset. NOTE The foreground receive buffer can be read anytime but cannot be written. The transmit buffers can be read or written anytime. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 137

MSCAN08 Controller (MSCAN08) Addr. Register Bit 7 6 5 4 3 2 1 Bit 0 Read: $05b0 IDR0 ID28 ID27 ID26 ID25 ID24 ID23 ID22 ID21 Write: Read: $05b1 IDR1 ID20 ID19 ID18 SRR (=1) IDE (=1) ID17 ID16 ID15 Write: Read: $05b2 IDR2 ID14 ID13 ID12 ID11 ID10 ID9 ID8 ID7 Write: Read: $05b3 IDR3 ID6 ID5 ID4 ID3 ID2 ID1 ID0 RTR Write: Read: $05b4 DSR0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Write: Read: $05b5 DSR1 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Write: Read: $05b6 DSR2 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Write: Read: $05b7 DSR3 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Write: Read: $05b8 DSR4 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Write: Read: $05b9 DSR5 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Write: Read: $05bA DSR6 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Write: Read: $05bB DSR7 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Write: Read: $05bC DLR DLC3 DLC2 DLC1 DLC0 Write: = Unimplemented Figure 12-12. Receive/Transmit Message Buffer Extended Identifier (IDRn) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 138 Freescale Semiconductor

Programmer’s Model of Message Storage Addr. Register Bit 7 6 5 4 3 2 1 Bit 0 Read: $05b0 IDR0 ID10 ID9 ID8 ID7 ID6 ID5 ID4 ID3 Write: Read: $05b1 IDR1 ID2 ID1 ID0 RTR IDE (=0) Write: Read: $05b2 IDR2 Write: Read: $05b3 IDR3 Write: = Unimplemented Figure 12-13. Standard Identifier Mapping 12.12.2 Identifier Registers The identifiers consist of either 11 bits (ID10–ID0) for the standard, or 29 bits (ID28–ID0) for the extended format. ID10/28 is the most significant bit and is transmitted first on the bus during the arbitration procedure. The priority of an identifier is defined to be highest for the smallest binary number. SRR — Substitute Remote Request This fixed recessive bit is used only in extended format. It must be set to 1 by the user for transmission buffers and will be stored as received on the CAN bus for receive buffers. IDE — ID Extended This flag indicates whether the extended or standard identifier format is applied in this buffer. In case of a receive buffer, the flag is set as being received and indicates to the CPU how to process the buffer identifier registers. In case of a transmit buffer, the flag indicates to the MSCAN08 what type of identifier to send. 1 = Extended format, 29 bits 0 = Standard format, 11 bits RTR — Remote Transmission Request This flag reflects the status of the remote transmission request bit in the CAN frame. In case of a receive buffer, it indicates the status of the received frame and supports the transmission of an answering frame in software. In case of a transmit buffer, this flag defines the setting of the RTR bit to be sent. 1 = Remote frame 0 = Data frame MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 139

MSCAN08 Controller (MSCAN08) 12.12.3 Data Length Register (DLR) This register keeps the data length field of the CAN frame. DLC3–DLC0 — Data Length Code Bits The data length code contains the number of bytes (data byte count) of the respective message. At transmission of a remote frame, the data length code is transmitted as programmed while the number of transmitted bytes is always 0. The data byte count ranges from 0 to 8 for a data frame. Table 12-5 shows the effect of setting the DLC bits. Table 12-5. Data Length Codes Data Length Code Data Byte DLC3 DLC2 DLC1 DLC0 Count 0 0 0 0 0 0 0 0 1 1 0 0 1 0 2 0 0 1 1 3 0 1 0 0 4 0 1 0 1 5 0 1 1 0 6 0 1 1 1 7 1 0 0 0 8 12.12.4 Data Segment Registers (DSRn) The eight data segment registers contain the data to be transmitted or received. The number of bytes to be transmitted or being received is determined by the data length code in the corresponding DLR. 12.12.5 Transmit Buffer Priority Registers Address: $05bD Bit 7 6 5 4 3 2 1 Bit 0 Read: PRIO7 PRIO6 PRIO5 PRIO4 PRIO3 PRIO2 PRIO1 PRIO0 Write: Reset: Unaffected by reset Figure 12-14. Transmit Buffer Priority Register (TBPR) PRIO7–PRIO0 — Local Priority This field defines the local priority of the associated message buffer. The local priority is used for the internal prioritization process of the MSCAN08 and is defined to be highest for the smallest binary number. The MSCAN08 implements the following internal prioritization mechanism: (cid:129) All transmission buffers with a cleared TXE flag participate in the prioritization right before the SOF is sent. (cid:129) The transmission buffer with the lowest local priority field wins the prioritization. (cid:129) In case more than one buffer has the same lowest priority, the message buffer with the lower index number wins. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 140 Freescale Semiconductor

Programmer’s Model of Control Registers 12.13 Programmer’s Model of Control Registers The programmer’s model has been laid out for maximum simplicity and efficiency. Figure 12-15 gives an overview on the control register block of the MSCAN08. Addr. Register Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 SYNCH SLPAK $0500 CMCR0 TLNKEN SLPRQ SFTRES Write: Read: 0 0 0 0 0 $0501 CMCR1 LOOPB WUPM CLKSRC Read: $0502 CBTR0 SJW1 SJW0 BRP5 BRP4 BRP3 BRP2 BRP1 BRP0 Write: Read: $0503 CBTR1 SAMP TSEG22 TSEG21 TSEG20 TSEG13 TSEG12 TSEG11 TSEG10 Write: Read: $0504 CRFLG WUPIF RWRNIF TWRNIF RERRIF TERRIF BOFFIF OVRIF RXF Write: Read: $0505 CRIER WUPIE RWRNIE TWRNIE RERRIE TERRIE BOFFIE OVRIE RXFIE Write: Read: 0 ABTAK2 ABTAK1 ABTAK0 0 $0506 CTFLG TXE2 TXE1 TXE0 Write: Read: 0 0 $0507 CTCR ABTRQ2 ABTRQ1 ABTRQ0 TXEIE2 TXEIE1 TXEIE0 Write: Read: 0 0 0 0 IDHIT1 IDHIT0 $0508 CIDAC IDAM1 IDAM0 Write: Read: $0509 Reserved R R R R R R R R Write: Read: $050E CRXERR RXERR7 RXERR6 RXERR5 RXERR4 RXERR3 RXERR2 RXERR1 RXERR0 Write: Read: $050F CTXERR TXERR7 TXERR6 TXERR5 TXERR4 TXERR3 TXERR2 TXERR1 TXERR0 Write: Read: $0510 CIDAR0 AC7 AC6 AC5 AC4 AC3 AC2 AC1 AC0 Write: Read: $0511 CIDAR1 AC7 AC6 AC5 AC4 AC3 AC2 AC1 AC0 Write: = Unimplemented R = Reserved Figure 12-15. MSCAN08 Control Register Structure MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 141

MSCAN08 Controller (MSCAN08) Addr. Register Bit 7 6 5 4 3 2 1 Bit 0 Read: $0512 CIDAR2 AC7 AC6 AC5 AC4 AC3 AC2 AC1 AC0 Write: Read: $0513 CIDAR3 AC7 AC6 AC5 AC4 AC3 AC2 AC1 AC0 Write: Read: $0514 CIDMR0 AM7 AM6 AM5 AM4 AM3 AM2 AM1 AM0 Write: Read: $0515 CIDMR1 AM7 AM6 AM5 AM4 AM3 AM2 AM1 AM0 Write: Read: $0516 CIDMR2 AM7 AM6 AM5 AM4 AM3 AM2 AM1 AM0 Write: Read: $0517 CIDMR3 AM7 AM6 AM5 AM4 AM3 AM2 AM1 AM0 Write: = Unimplemented R = Reserved Figure 12-15. MSCAN08 Control Register Structure (Continued) 12.13.1 MSCAN08 Module Control Register 0 Address: $0500 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 SYNCH SLPAK TLNKEN SLPRQ SFTRES Write: Reset: 0 0 0 0 0 0 0 1 = Unimplemented Figure 12-16. Module Control Register 0 (CMCR0) SYNCH — Synchronized Status This bit indicates whether the MSCAN08 is synchronized to the CAN bus and as such can participate in the communication process. 1 = MSCAN08 synchronized to the CAN bus 0 = MSCAN08 not synchronized to the CAN bus TLNKEN — Timer Enable This flag is used to establish a link between the MSCAN08 and the on-chip timer (see 12.9 Timer Link). 1 = The MSCAN08 timer signal output is connected to the timer input. 0 = The port is connected to the timer input. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 142 Freescale Semiconductor

Programmer’s Model of Control Registers SLPAK — Sleep Mode Acknowledge This flag indicates whether the MSCAN08 is in module internal sleep mode. It shall be used as a handshake for the sleep mode request (see 12.8.1 MSCAN08 Sleep Mode). If the MSCAN08 detects bus activity while in sleep mode, it clears the flag. 1 = Sleep – MSCAN08 in internal sleep mode 0 = Wakeup – MSCAN08 is not in sleep mode SLPRQ — Sleep Request, Go to Internal Sleep Mode This flag requests the MSCAN08 to go into an internal power-saving mode (see 12.8.1 MSCAN08 Sleep Mode). 1 = Sleep — The MSCAN08 will go into internal sleep mode. 0 = Wakeup — The MSCAN08 will function normally. SFTRES — Soft Reset When this bit is set by the CPU, the MSCAN08 immediately enters the soft reset state. Any ongoing transmission or reception is aborted and synchronization to the bus is lost. The following registers enter and stay in their hard reset state: CMCR0, CRFLG, CRIER, CTFLG, and CTCR. The registers CMCR1, CBTR0, CBTR1, CIDAC, CIDAR0–CIDAR3, and CIDMR0–CIDMR3 can only be written by the CPU when the MSCAN08 is in soft reset state. The values of the error counters are not affected by soft reset. When this bit is cleared by the CPU, the MSCAN08 tries to synchronize to the CAN bus. If the MSCAN08 is not in bus-off state, it will be synchronized after 11 recessive bits on the bus; if the MSCAN08 is in bus-off state, it continues to wait for 128 occurrences of 11 recessive bits. Clearing SFTRES and writing to other bits in CMCR0 must be in separate instructions. 1 = MSCAN08 in soft reset state 0 = Normal operation 12.13.2 MSCAN08 Module Control Register 1 Address: $0501 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 0 LOOPB WUPM CLKSRC Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 12-17. Module Control Register (CMCR1) LOOPB — Loop Back Self-Test Mode When this bit is set, the MSCAN08 performs an internal loop back which can be used for self-test operation: the bit stream output of the transmitter is fed back to the receiver internally. The CAN RX input pin is ignored and the CAN output goes to the recessive state (logic 1). The MSCAN08 TX behaves as it does normally when transmitting and treats its own transmitted message as a message received from a remote node. In this state the MSCAN08 ignores the bit sent during the ACK slot of the CAN frame Acknowledge field to insure proper reception of its own message. Both transmit and receive interrupts are generated. 1 = Activate loop back self-test mode 0 = Normal operation MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 143

MSCAN08 Controller (MSCAN08) WUPM — Wakeup Mode This flag defines whether the integrated low-pass filter is applied to protect the MSCAN08 from spurious wakeups (see 12.8.5 Programmable Wakeup Function). 1 = MSCAN08 will wakeup the CPU only in cases of a dominant pulse on the bus which has a length of at least t . wup 0 = MSCAN08 will wakeup the CPU after any recessive-to-dominant edge on the CAN bus. CLKSRC — Clock Source This flag defines which clock source the MSCAN08 module is driven from (see 12.10 Clock System). 1 = The MSCAN08 clock source is CGMOUT (see Figure 12-8). 0 = The MSCAN08 clock source is CGMXCLK/2 (see Figure 12-8). NOTE The CMCR1 register can be written only if the SFTRES bit in the MSCAN08 module control register is set 12.13.3 MSCAN08 Bus Timing Register 0 Address: $0502 Bit 7 6 5 4 3 2 1 Bit 0 Read: SJW1 SJW0 BRP5 BRP4 BRP3 BRP2 BRP1 BRP0 Write: Reset: 0 0 0 0 0 0 0 0 Figure 12-18. Bus Timing Register 0 (CBTR0) SJW1 and SJW0 — Synchronization Jump Width The synchronization jump width (SJW) defines the maximum number of time quanta (T ) clock cycles q by which a bit may be shortened, or lengthened, to achieve resynchronization on data transitions on the bus (see Table 12-6). Table 12-6. Synchronization Jump Width Synchronization SJW1 SJW0 Jump Width 0 0 1 Tq cycle 0 1 2 Tq cycle 1 0 3 Tq cycle 1 1 4 Tq cycle BRP5–BRP0 — Baud Rate Prescaler These bits determine the time quanta (T ) clock, which is used to build up the individual bit timing, q according to Table 12-7. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 144 Freescale Semiconductor

Programmer’s Model of Control Registers Table 12-7. Baud Rate Prescaler Prescaler BRP5 BRP4 BRP3 BRP2 BRP1 BRP0 Value (P) 0 0 0 0 0 0 1 0 0 0 0 0 1 2 0 0 0 0 1 0 3 0 0 0 0 1 1 4 : : : : : : : : : : : : : : 1 1 1 1 1 1 64 NOTE The CBTR0 register can be written only if the SFTRES bit in the MSCAN08 module control register is set. 12.13.4 MSCAN08 Bus Timing Register 1 Address: $0503 Bit 7 6 5 4 3 2 1 Bit 0 Read: SAMP TSEG22 TSEG21 TSEG20 TSEG13 TSEG12 TSEG11 TSEG10 Write: Reset: 0 0 0 0 0 0 0 0 Figure 12-19. Bus Timing Register 1 (CBTR1) SAMP — Sampling This bit determines the number of serial bus samples to be taken per bit time. If set, three samples per bit are taken, the regular one (sample point) and two preceding samples, using a majority rule. For higher bit rates, SAMP should be cleared, which means that only one sample will be taken per bit. 1 = Three samples per bit(1) 0 = One sample per bit TSEG22–TSEG10 — Time Segment Time segments within the bit time fix the number of clock cycles per bit time and the location of the sample point. Time segment 1 (TSEG1) and time segment 2 (TSEG2) are programmable as shown in Table 12-8. The bit time is determined by the oscillator frequency, the baud rate prescaler, and the number of time quanta (T ) clock cycles per bit as shown in Table 12-4). q Pres value Bit time = (cid:129) number of time quanta f MSCANCLK NOTE The CBTR1 register can only be written if the SFTRES bit in the MSCAN08 module control register is set. 1. In this case PHASE_SEG1 must be at least 2 time quanta. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 145

MSCAN08 Controller (MSCAN08) Table 12-8. Time Segment Values Time Time TSEG13 TSEG12 TSEG11 TSEG10 TSEG22 TSEG21 TSEG20 Segment 1 Segment 2 0 0 0 0 1 T Cycle(1) 0 0 0 1 T Cycle(1) q q 0 0 0 1 2 Tq Cycles(1) 0 0 1 2 Tq Cycles 0 0 1 0 3T Cycles(1) . . . . q 0 0 1 1 4 Tq Cycles . . . . . . . . . 1 1 1 8Tq Cycles . . . . . 1 1 1 1 16 Tq Cycles 1. This setting is not valid. Please refer to Table12-4 for valid settings. 12.13.5 MSCAN08 Receiver Flag Register (CRFLG) All bits of this register are read and clear only. A flag can be cleared by writing a 1 to the corresponding bit position. A flag can be cleared only when the condition which caused the setting is valid no more. Writing a 0 has no effect on the flag setting. Every flag has an associated interrupt enable flag in the CRIER register. A hard or soft reset will clear the register. Address: $0504 Bit 7 6 5 4 3 2 1 Bit 0 Read: WUPIF RWRNIF TWRNIF RERRIF TERRIF BOFFIF OVRIF RXF Write: Reset: 0 0 0 0 0 0 0 0 Figure 12-20. Receiver Flag Register (CRFLG) WUPIF — Wakeup Interrupt Flag If the MSCAN08 detects bus activity while in sleep mode, it sets the WUPIF flag. If not masked, a wakeup interrupt is pending while this flag is set. 1 = MSCAN08 has detected activity on the bus and requested wakeup. 0 = No wakeup interrupt has occurred. RWRNIF — Receiver Warning Interrupt Flag This flag is set when the MSCAN08 goes into warning status due to the receive error counter (REC) exceeding 96 and neither one of the error interrupt flags or the bus-off interrupt flag is set(1). If not masked, an error interrupt is pending while this flag is set. 1 = MSCAN08 has gone into receiver warning status. 0 = No receiver warning status has been reached. 1. Condition to set the flag: RWRNIF = (96 → REC) & RERRIF & TERRIF & BOFFIF MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 146 Freescale Semiconductor

Programmer’s Model of Control Registers TWRNIF — Transmitter Warning Interrupt Flag This flag is set when the MSCAN08 goes into warning status due to the transmit error counter (TEC) exceeding 96 and neither one of the error interrupt flags or the bus-off interrupt flag is set(1). If not masked, an error interrupt is pending while this flag is set. 1 = MSCAN08 has gone into transmitter warning status. 0 = No transmitter warning status has been reached. RERRIF — Receiver Error Passive Interrupt Flag This flag is set when the MSCAN08 goes into error passive status due to the receive error counter exceeding 127 and the bus-off interrupt flag is not set(2). If not masked, an error interrupt is pending while this flag is set. 1 = MSCAN08 has gone into receiver error passive status. 0 = No receiver error passive status has been reached. TERRIF — Transmitter Error Passive Interrupt Flag This flag is set when the MSCAN08 goes into error passive status due to the transmit error counter exceeding 127 and the bus-off interrupt flag is not set(3). If not masked, an error interrupt is pending while this flag is set. 1 = MSCAN08 went into transmit error passive status. 0 = No transmit error passive status has been reached. BOFFIF — Bus-Off Interrupt Flag This flag is set when the MSCAN08 goes into bus-off status, due to the transmit error counter exceeding 255. It cannot be cleared before the MSCAN08 has monitored 128 times 11 consecutive ‘recessive’ bits on the bus. If not masked, an error interrupt is pending while this flag is set. 1 = MSCAN08has gone into bus-off status. 0 = No bus-off status has been reached. OVRIF — Overrun Interrupt Flag This flag is set when a data overrun condition occurs. If not masked, an error interrupt is pending while this flag is set. 1 = A data overrun has been detected since last clearing the flag. 0 = No data overrun has occurred. RXF — Receive Buffer Full The RXF flag is set by the MSCAN08 when a new message is available in the foreground receive buffer. This flag indicates whether the buffer is loaded with a correctly received message. After the CPU has read that message from the receive buffer the RXF flag must be cleared to release the buffer. A set RXF flag prohibits the exchange of the background receive buffer into the foreground buffer. If not masked, a receive interrupt is pending while this flag is set. 1 = The receive buffer is full. A new message is available. 0 = The receive buffer is released (not full). NOTE To ensure data integrity, no registers of the receive buffer shall be read while the RXF flag is cleared. 1. Condition to set the flag: TWRNIF = (96 → TEC) & RERRIF & TERRIF & BOFFIF 2. Condition to set the flag: RERRIF = (127 → REC → 255) & BOFFIF 3. Condition to set the flag: TERRIF = (128 → TEC → 255) & BOFFIF MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 147

MSCAN08 Controller (MSCAN08) The CRFLG register is held in the reset state when the SFTRES bit in CMCR0 is set. 12.13.6 MSCAN08 Receiver Interrupt Enable Register Address: $0505 Bit 7 6 5 4 3 2 1 Bit 0 Read: WUPIE RWRNIE TWRNIE RERRIE TERRIE BOFFIE OVRIE RXFIE Write: Reset: 0 0 0 0 0 0 0 0 Figure 12-21. Receiver Interrupt Enable Register (CRIER) WUPIE — Wakeup Interrupt Enable 1 = A wakeup event will result in a wakeup interrupt. 0 = No interrupt will be generated from this event. RWRNIE — Receiver Warning Interrupt Enable 1 = A receiver warning status event will result in an error interrupt. 0 = No interrupt is generated from this event. TWRNIE — Transmitter Warning Interrupt Enable 1 = A transmitter warning status event will result in an error interrupt. 0 = No interrupt is generated from this event. RERRIE — Receiver Error Passive Interrupt Enable 1 = A receiver error passive status event will result in an error interrupt. 0 = No interrupt is generated from this event. TERRIE — Transmitter Error Passive Interrupt Enable 1 = A transmitter error passive status event will result in an error interrupt. 0 = No interrupt is generated from this event. BOFFIE — Bus-Off Interrupt Enable 1 = A bus-off event will result in an error interrupt. 0 = No interrupt is generated from this event. OVRIE — Overrun Interrupt Enable 1 = An overrun event will result in an error interrupt. 0 = No interrupt is generated from this event. RXFIE — Receiver Full Interrupt Enable 1 = A receive buffer full (successful message reception) event will result in a receive interrupt. 0 = No interrupt will be generated from this event. NOTE The CRIER register is held in the reset state when the SFTRES bit in CMCR0 is set. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 148 Freescale Semiconductor

Programmer’s Model of Control Registers 12.13.7 MSCAN08 Transmitter Flag Register The abort acknowledge flags are read only. The transmitter buffer empty flags are read and clear only. A flag can be cleared by writing a 1 to the corresponding bit position. Writing a 0 has no effect on the flag setting. The transmitter buffer empty flags each have an associated interrupt enable bit in the CTCR register. A hard or soft reset will resets the register. Address: $0506 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 ABTAK2 ABTAK1 ABTAK0 0 TXE2 TXE1 TXE0 Write: Reset: 0 0 0 0 0 1 1 1 = Unimplemented Figure 12-22. Transmitter Flag Register (CTFLG) ABTAK2–ABTAK0 — Abort Acknowledge This flag acknowledges that a message has been aborted due to a pending abort request from the CPU. After a particular message buffer has been flagged empty, this flag can be used by the application software to identify whether the message has been aborted successfully or has been sent. The ABTAKx flag is cleared implicitly whenever the corresponding TXE flag is cleared. 1 = The message has been aborted. 0 = The message has not been aborted, thus has been sent out. TXE2–TXE0 — Transmitter Empty This flag indicates that the associated transmit message buffer is empty, thus not scheduled for transmission. The CPU must handshake (clear) the flag after a message has been set up in the transmit buffer and is due for transmission. The MSCAN08 sets the flag after the message has been sent successfully. The flag is also set by the MSCAN08 when the transmission request was successfully aborted due to a pending abort request (see 12.12.5 Transmit Buffer Priority Registers). If not masked, a receive interrupt is pending while this flag is set. Clearing a TXEx flag also clears the corresponding ABTAKx flag (ABTAK, see above). When a TXEx flag is set, the corresponding ABTRQx bit (ABTRQ) is cleared. See 12.13.8 MSCAN08 Transmitter Control Register 1 = The associated message buffer is empty (not scheduled). 0 = The associated message buffer is full (loaded with a message due for transmission). NOTE To ensure data integrity, no registers of the transmit buffers should be written to while the associated TXE flag is cleared. The CTFLG register is held in the reset state when the SFTRES bit in CMCR0 is set. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 149

MSCAN08 Controller (MSCAN08) 12.13.8 MSCAN08 Transmitter Control Register Address: $0507 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 ABTRQ2 ABTRQ1 ABTRQ0 TXEIE2 TXEIE1 TXEIE0 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 12-23. Transmitter Control Register (CTCR) ABTRQ2–ABTRQ0 — Abort Request The CPU sets an ABTRQx bit to request that an already scheduled message buffer (TXE = 0) be aborted. The MSCAN08 will grant the request if the message has not already started transmission, or if the transmission is not successful (lost arbitration or error). When a message is aborted the associated TXE and the abort acknowledge flag (ABTAK) (see 12.13.7 MSCAN08 Transmitter Flag Register) will be set and an TXE interrupt is generated if enabled. The CPU cannot reset ABTRQx. ABTRQx is cleared implicitly whenever the associated TXE flag is set. 1 = Abort request pending 0 = No abort request NOTE The software must not clear one or more of the TXE flags in CTFLG and simultaneously set the respective ABTRQ bit(s). TXEIE2–TXEIE0 — Transmitter Empty Interrupt Enable 1 = A transmitter empty (transmit buffer available for transmission) event results in a transmitter empty interrupt. 0 = No interrupt is generated from this event. NOTE The CTCR register is held in the reset state when the SFTRES bit in CMCR0 is set. 12.13.9 MSCAN08 Identifier Acceptance Control Register Address: $0508 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 IDHIT1 IDHIT0 IDAM1 IDAM0 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 12-24. Identifier Acceptance Control Register (CIDAC) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 150 Freescale Semiconductor

Programmer’s Model of Control Registers IDAM1–IDAM0— Identifier Acceptance Mode The CPU sets these flags to define the identifier acceptance filter organization (see 12.5 Identifier Acceptance Filter). Table 12-9 summarizes the different settings. In “filter closed” mode no messages will be accepted so that the foreground buffer will never be reloaded. Table 12-9. Identifier Acceptance Mode Settings IDAM1 IDAM0 Identifier Acceptance Mode 0 0 Single 32-bit acceptance filter 0 1 Two 16-bit acceptance filter 1 0 Four 8-bit acceptance filters 1 1 Filter closed IDHIT1–IDHIT0— Identifier Acceptance Hit Indicator The MSCAN08 sets these flags to indicate an identifier acceptance hit (see 12.5 Identifier Acceptance Filter). Table 12-9 summarizes the different settings. Table 12-10. Identifier Acceptance Hit Indication IDHIT1 IDHIT0 Identifier Acceptance Hit 0 0 Filter 0 hit 0 1 Filter 1 hit 1 0 Filter 2 hit 1 1 Filter 3 hit The IDHIT indicators are always related to the message in the foreground buffer. When a message gets copied from the background to the foreground buffer, the indicators are updated as well. NOTE The CIDAC register can be written only if the SFTRES bit in the CMCR0 is set. 12.13.10 MSCAN08 Receive Error Counter Address: $050E Bit 7 6 5 4 3 2 1 Bit 0 Read: RXERR7 RXERR6 RXERR5 RXERR4 RXERR3 RXERR2 RXERR1 RXERR0 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 12-25. Receiver Error Counter (CRXERR) This read-only register reflects the status of the MSCAN08 receive error counter. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 151

MSCAN08 Controller (MSCAN08) 12.13.11 MSCAN08 Transmit Error Counter Address: $050F Bit 7 6 5 4 3 2 1 Bit 0 Read: TXERR7 TXERR6 TXERR5 TXERR4 TXERR3 TXERR2 TXERR1 TXERR0 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 12-26. Transmit Error Counter (CTXERR) This read-only register reflects the status of the MSCAN08 transmit error counter. NOTE Both error counters may only be read when in sleep or soft reset mode. 12.13.12 MSCAN08 Identifier Acceptance Registers On reception each message is written into the background receive buffer. The CPU is only signalled to read the message, however, if it passes the criteria in the identifier acceptance and identifier mask registers (accepted); otherwise, the message will be overwritten by the next message (dropped). The acceptance registers of the MSCAN08 are applied on the IDR0 to IDR3 registers of incoming messages in a bit by bit manner. For extended identifiers, all four acceptance and mask registers are applied. For standard identifiers only the first two (CIDMR0/CIDMR1 and CIDAR0/CIDAR1) are applied. CIDAR0 Address: $0510 Bit 7 6 5 4 3 2 1 Bit 0 Read: AC7 AC6 AC5 AC4 AC3 AC2 AC1 AC0 Write: Reset: Unaffected by reset CIDAR1 Address: $050511 Bit 7 6 5 4 3 2 1 Bit 0 Read: AC7 AC6 AC5 AC4 AC3 AC2 AC1 AC0 Write: Reset: Unaffected by reset CIDAR2 Address: $0512 Bit 7 6 5 4 3 2 1 Bit 0 Read: AC7 AC6 AC5 AC4 AC3 AC2 AC1 AC0 Write: Reset: Unaffected by reset CIDAR3 Address: $0513 Bit 7 6 5 4 3 2 1 Bit 0 Read: AC7 AC6 AC5 AC4 AC3 AC2 AC1 AC0 Write: Reset: Unaffected by reset Figure 12-27. Identifier Acceptance Registers (CIDAR0–CIDAR3) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 152 Freescale Semiconductor

Programmer’s Model of Control Registers AC7–AC0 — Acceptance Code Bits AC7–AC0 comprise a user-defined sequence of bits with which the corresponding bits of the related identifier register (IDRn) of the receive message buffer are compared. The result of this comparison is then masked with the corresponding identifier mask register. NOTE The CIDAR0–CIDAR3 registers can be written only if the SFTRES bit in CMCR0 is set 12.13.13 MSCAN08 Identifier Mask Registers (CIDMR0–CIDMR3) The identifier mask registers specify which of the corresponding bits in the identifier acceptance register are relevant for acceptance filtering. For standard identifiers it is required to program the last three bits (AM2–AM0) in the mask register CIDMR1 to ‘don’t care’. CIDMRO Address: $0514 Bit 7 6 5 4 3 2 1 Bit 0 Read: AM7 AM6 AM5 AM4 AM3 AM2 AM1 AM0 Write: Reset: Unaffected by reset CIDMR1 Address: $0515 Bit 7 6 5 4 3 2 1 Bit 0 Read: AM7 AM6 AM5 AM4 AM3 AM2 AM1 AM0 Write: Reset: Unaffected by reset CIDMR2 Address: $0516 Bit 7 6 5 4 3 2 1 Bit 0 Read: AM7 AM6 AM5 AM4 AM3 AM2 AM1 AM0 Write: Reset: Unaffected by reset CIDMR3 Address: $0517 Bit 7 6 5 4 3 2 1 Bit 0 Read: AM7 AM6 AM5 AM4 AM3 AM2 AM1 AM0 Write: Reset: Unaffected by reset Figure 12-28. Identifier Mask Registers (CIDMR0–CIDMR3) AM7–AM0 — Acceptance Mask Bits If a particular bit in this register is cleared, this indicates that the corresponding bit in the identifier acceptance register must be the same as its identifier bit before a match will be detected. The message will be accepted if all such bits match. If a bit is set, it indicates that the state of the corresponding bit in the identifier acceptance register will not affect whether or not the message is accepted. 1 = Ignore corresponding acceptance code register bit. 0 = Match corresponding acceptance code register and identifier bits. NOTE The CIDMR0–CIDMR3 registers can be written only if the SFTRES bit in the CMCR0 is set MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 153

MSCAN08 Controller (MSCAN08) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 154 Freescale Semiconductor

Chapter 13 Input/Output (I/O) Ports 13.1 Introduction Bidirectional input-output (I/O) pins form five parallel ports. All I/O pins are programmable as inputs or outputs. All individual bits within port A, port C, and port D are software configurable with pullup devices if configured as input port bits. The pullup devices are automatically and dynamically disabled when a port bit is switched to output mode. 13.2 Unused Pin Termination Input pins and I/O port pins that are not used in the application must be terminated. This prevents excess current caused by floating inputs, and enhances immunity during noise or transient events. Termination methods include: 1. Configuring unused pins as outputs and driving high or low; 1. Configuring unused pins as inputs and enabling internal pull-ups; 1. Configuring unused pins as inputs and using external pull-up or pull-down resistors. Never connect unused pins directly to V or V . DD SS Since some general-purpose I/O pins are not available on all packages, these pins must be terminated as well. Either method 1 or 2 above are appropriate. Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: Port A Data Register PTA7 PTA6 PTA5 PTA4 PTA3 PTA2 PTA1 PTA0 $0000 (PTA) Write: See page 158. Reset: Unaffected by reset Read: Port B Data Register PTB7 PTB6 PTB5 PTB4 PTB3 PTB2 PTB1 PTB0 $0001 (PTB) Write: See page 160. Reset: Unaffected by reset Read: 1 Port C Data Register PTC6 PTC5 PTC4 PTC3 PTC2 PTC1 PTC0 $0002 (PTC) Write: See page 162. Reset: Unaffected by reset Read: Port D Data Register PTD7 PTD6 PTD5 PTD4 PTD3 PTD2 PTD1 PTD0 $0003 (PTD) Write: See page 164. Reset: Unaffected by reset = Unimplemented Figure 13-1. I/O Port Register Summary MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 155

Input/Output (I/O) Ports Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: Data Direction Register A DDRA7 DDRA6 DDRA5 DDRA4 DDRA3 DDRA2 DDRA1 DDRA0 $0004 (DDRA) Write: See page 158. Reset: 0 0 0 0 0 0 0 0 Read: Data Direction Register B DDRB7 DDRB6 DDRB5 DDRB4 DDRB3 DDRB2 DDRB1 DDRB0 $0005 (DDRB) Write: See page 161. Reset: 0 0 0 0 0 0 0 0 Read: 0 Data Direction Register C DDRC6 DDRC5 DDRC4 DDRC3 DDRC2 DDRC1 DDRC0 $0006 (DDRC) Write: See page 162. Reset: 0 0 0 0 0 0 0 0 Read: Data Direction Register D DDRD7 DDRD6 DDRD5 DDRD4 DDRD3 DDRD2 DDRD1 DDRD0 $0007 (DDRD) Write: See page 165. Reset: 0 0 0 0 0 0 0 0 Read: 0 0 Port E Data Register PTE5 PTE4 PTE3 PTE2 PTE1 PTE0 $0008 (PTE) Write: See page 167. Reset: Unaffected by reset Read: 0 0 Data Direction Register E DDRE5 DDRE4 DDRE3 DDRE2 DDRE1 DDRE0 $000C (DDRE) Write: See page 168. Reset: 0 0 0 0 0 0 0 0 Read: Port A Input Pullup Enable PTAPUE7 PTAPUE6 PTAPUE5 PTAPUE4 PTAPUE3 PTAPUE2 PTAPUE1 PTAPUE0 $000D Register (PTAPUE) Write: See page 159. Reset: 0 0 0 0 0 0 0 0 Read: 0 Port C Input Pullup Enable PTCPUE6 PTCPUE5 PTCPUE4 PTCPUE3 PTCPUE2 PTCPUE1 PTCPUE0 $000E Register (PTCPUE) Write: See page 164. Reset: 0 0 0 0 0 0 0 0 Read: Port D Input Pullup Enable PTDPUE7 PTDPUE6 PTDPUE5 PTDPUE4 PTDPUE3 PTDPUE2 PTDPUE1 PTDPUE0 $000F Register (PTDPUE) Write: See page 166. Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 13-1. I/O Port Register Summary (Continued) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 156 Freescale Semiconductor

Unused Pin Termination Table 13-1. Port Control Register Bits Summary Port Bit DDR Module Control Pin 0 DDRA0 KBIE0 PTA0/KBD0 1 DDRA1 KBIE1 PTA1/KBD1 2 DDRA2 KBIE2 PTA2/KBD2 3 DDRA3 KBIE3 PTA3/KBD3 A KBD 4 DDRA4 KBIE4 PTA4/KBD4 5 DDRA5 KBIE5 PTA5/KBD5 6 DDRA6 KBIE6 PTA6/KBD6 7 DDRA7 KBIE7 PTA7/KBD7 0 DDRB0 PTB0/AD0 1 DDRB1 PTB1/AD1 2 DDRB2 PTB2/AD2 3 DDRB3 PTB3/AD3 B ADC ADCH4–ADCH0 4 DDRB4 PTB4/AD4 5 DDRB5 PTB5/AD5 6 DDRB6 PTB6/AD6 7 DDRB7 PTB7/AD7 0 DDRC0 PTC0 MSCAN08 CANEN 1 DDRC1 PTC1 2 DDRC2 PTC2 C 3 DDRC3 PTC3 4 DDRC4 PTC4 5 DDRC5 PTC5 6 DDRC6 PTC6 0 DDRD0 PTD0/SS 1 DDRD1 PTD1/MISO SPI SPE 2 DDRD2 PTD2/MOSI 3 DDRD3 PTD3/SPSCK D 4 DDRD4 ELS0B:ELS0A PTD4/T1CH0 TIM1 5 DDRD5 ELS1B:ELS1A PTD5/T1CH1 6 DDRD6 ELS0B:ELS0A PTD6/T2CH0 TIM2 7 DDRD7 ELS1B:ELS1A PTD7/T2CH1 0 DDRE0 PTE0/TxD SCI ENSCI 1 DDRE1 PTE1/RxD 2 DDRE2 PTE2 E 3 DDRE3 PTE3 4 DDRE4 PTE4 5 DDRE5 PTE5 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 157

Input/Output (I/O) Ports 13.3 Port A Port A is an 8-bit special-function port that shares all eight of its pins with the keyboard interrupt (KBI) module. Port A also has software configurable pullup devices if configured as an input port. 13.3.1 Port A Data Register The port A data register (PTA) contains a data latch for each of the eight port A pins. Address: $0000 Bit 7 6 5 4 3 2 1 Bit 0 Read: PTA7 PTA6 PTA5 PTA4 PTA3 PTA2 PTA1 PTA0 Write: Reset: Unaffected by reset Alternative KBD7 KBD6 KBD5 KBD4 KBD3 KBD2 KBD1 KBD0 Function: Figure 13-2. Port A Data Register (PTA) PTA7–PTA0 — Port A Data Bits These read/write bits are software programmable. Data direction of each port A pin is under the control of the corresponding bit in data direction register A. Reset has no effect on port A data. KBD7–KBD0 — Keyboard Inputs The keyboard interrupt enable bits, KBIE7–KBIE0, in the keyboard interrupt control register (KBICR) enable the port A pins as external interrupt pins. See Chapter 9 Keyboard Interrupt Module (KBI). 13.3.2 Data Direction Register A Data direction register A (DDRA) determines whether each port A pin is an input or an output. Writing a logic 1 to a DDRA bit enables the output buffer for the corresponding port A pin; a logic 0 disables the output buffer. Address: $0004 Bit 7 6 5 4 3 2 1 Bit 0 Read: DDRA7 DDRA6 DDRA5 DDRA4 DDRA3 DDRA2 DDRA1 DDRA0 Write: Reset: 0 0 0 0 0 0 0 0 Figure 13-3. Data Direction Register A (DDRA) DDRA7–DDRA0 — Data Direction Register A Bits These read/write bits control port A data direction. Reset clears DDRA7–DDRA0, configuring all port A pins as inputs. 1 = Corresponding port A pin configured as output 0 = Corresponding port A pin configured as input NOTE Avoid glitches on port A pins by writing to the port A data register before changing data direction register A bits from 0 to 1. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 158 Freescale Semiconductor

Port A Figure 13-4 shows the port A I/O logic. READ DDRA ($0004) WRITE DDRA ($0004) DDRAx RESET S U B A WRITE PTA ($0000) AT PTAx PTAx D V L DD A N R E T PTAPUEx N I INTERNAL PULLUP READ PTA ($0000) DEVICE Figure 13-4. Port A I/O Circuit When bit DDRAx is a logic 1, reading address $0000 reads the PTAx data latch. When bit DDRAx is a logic 0, reading address $0000 reads the voltage level on the pin. The data latch can always be written, regardless of the state of its data direction bit. Table 13-2 summarizes the operation of the port A pins. Table 13-2. Port A Pin Functions PTAPUE DDRA PTA I/O Pin Accesses to DDRA Accesses to PTA Bit Bit Bit Mode Read/Write Read Write 1 0 X(1) Input, VDD(2) DDRA7–DDRA0 Pin PTA7–PTA0(3) 0 0 X Input, Hi-Z(4) DDRA7–DDRA0 Pin PTA7–PTA0(3) X 1 X Output DDRA7–DDRA0 PTA7–PTA0 PTA7–PTA0 1. X = Don’t care 2. I/O pin pulled up to V by internal pullup device DD 3. Writing affects data register, but does not affect input. 4. Hi-Z = High impedance 13.3.3 Port A Input Pullup Enable Register The port A input pullup enable register (PTAPUE) contains a software configurable pullup device for each of the eight port A pins. Each bit is individually configurable and requires that the data direction register, DDRA, bit be configured as an input. Each pullup is automatically and dynamically disabled when a port bit’s DDRA is configured for output mode. Address: $000D Bit 7 6 5 4 3 2 1 Bit 0 Read: PTAPUE7 PTAPUE6 PTAPUE5 PTAPUE4 PTAPUE3 PTAPUE2 PTAPUE1 PTAPUE0 Write: Reset: 0 0 0 0 0 0 0 0 Figure 13-5. Port A Input Pullup Enable Register (PTAPUE) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 159

Input/Output (I/O) Ports PTAPUE7–PTAPUE0 — Port A Input Pullup Enable Bits These writable bits are software programmable to enable pullup devices on an input port bit. 1 = Corresponding port A pin configured to have internal pullup 0 = Corresponding port A pin has internal pullup disconnected 13.4 Port B Port B is an 8-bit special-function port that shares all eight of its pins with the analog-to-digital converter (ADC) module. 13.4.1 Port B Data Register The port B data register (PTB) contains a data latch for each of the eight port pins. Address: $0001 Bit 7 6 5 4 3 2 1 Bit 0 Read: PTB7 PTB6 PTB5 PTB4 PTB3 PTB2 PTB1 PTB0 Write: Reset: Unaffected by reset Alternative AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0 Function: Figure 13-6. Port B Data Register (PTB) PTB7–PTB0 — Port B Data Bits These read/write bits are software-programmable. Data direction of each port B pin is under the control of the corresponding bit in data direction register B. Reset has no effect on port B data. AD7–AD0 — Analog-to-Digital Input Bits AD7–AD0 are pins used for the input channels to the analog-to-digital converter module. The channel select bits in the ADC status and control register define which port B pin will be used as an ADC input and overrides any control from the port I/O logic by forcing that pin as the input to the analog circuitry. See Chapter 3 Analog-to-Digital Converter (ADC) for more information. NOTE Care must be taken when reading port B while applying analog voltages to AD7–AD0 pins. If the appropriate ADC channel is not enabled, excessive current drain may occur if analog voltages are applied to the PTBx/ADx pin, while PTB is read as a digital input. Those ports not selected as analog input channels are considered digital I/O ports. 13.4.2 Data Direction Register B Data direction register B (DDRB) determines whether each port B pin is an input or an output. Writing a logic 1 to a DDRB bit enables the output buffer for the corresponding port B pin; a logic 0 disables the output buffer. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 160 Freescale Semiconductor

Port B Address: $0005 Bit 7 6 5 4 3 2 1 Bit 0 Read: DDRB7 DDRB6 DDRB5 DDRB4 DDRB3 DDRB2 DDRB1 DDRB0 Write: Reset: 0 0 0 0 0 0 0 0 Figure 13-7. Data Direction Register B (DDRB) DDRB7–DDRB0 — Data Direction Register B Bits These read/write bits control port B data direction. Reset clears DDRB7–DDRB0, configuring all port B pins as inputs. 1 = Corresponding port B pin configured as output 0 = Corresponding port B pin configured as input NOTE Avoid glitches on port B pins by writing to the port B data register before changing data direction register B bits from 0 to 1. Figure 13-8 shows the port B I/O logic. READ DDRB ($0005) WRITE DDRB ($0005) S DDRBx BU RESET A T A D WRITE PTB ($0001) AL PTBx PTBx N R E T N I READ PTB ($0001) Figure 13-8. Port B I/O Circuit When bit DDRBx is a logic 1, reading address $0001 reads the PTBx data latch. When bit DDRBx is a logic 0, reading address $0001 reads the voltage level on the pin. The data latch can always be written, regardless of the state of its data direction bit. Table 13-3 summarizes the operation of the port B pins. Table 13-3. Port B Pin Functions DDRB PTB I/O Pin Accesses to DDRB Accesses to PTB Bit Bit Mode Read/Write Read Write 0 X(1) Input, Hi-Z(2) DDRB7–DDRB0 Pin PTB7–PTB0(3) 1 X Output DDRB7–DDRB0 PTB7–PTB0 PTB7–PTB0 1. X = Don’t care 2. Hi-Z = High impedance 3. Writing affects data register, but does not affect input. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 161

Input/Output (I/O) Ports 13.5 Port C Port C is a 7-bit, general-purpose bidirectional I/O port. Port C also has software configurable pullup devices if configured as an input port. 13.5.1 Port C Data Register The port C data register (PTC) contains a data latch for each of the seven port C pins. NOTE Bit 6 through bit 2 of PTC are not available in the 32-pin LQFP package. Address: $0002 Bit 7 6 5 4 3 2 1 Bit 0 Read: 1 PTC6 PTC5 PTC4 PTC3 PTC2 PTC1 PTC0 Write: Reset: Unaffected by reset Alternative CAN CAN Function: RX TX = Unimplemented Figure 13-9. Port C Data Register (PTC) PTC6–PTC0 — Port C Data Bits These read/write bits are software-programmable. Data direction of each port C pin is under the control of the corresponding bit in data direction register C. Reset has no effect on port C data. CAN and CAN — MSCAN08 Bits RX TX The CAN –CAN pins are the MSCAN08 modules receive and transmit pins. The CANEN bit in the RX TX MSCAN08 control register determines, whether the PTC1/CAN –PTC0/CAN pins are MSCAN08 RX TX pins or general-purpose I/O pins. See Chapter 12 MSCAN08 Controller (MSCAN08). 13.5.2 Data Direction Register C Data direction register C (DDRC) determines whether each port C pin is an input or an output. Writing a logic 1 to a DDRC bit enables the output buffer for the corresponding port C pin; a logic 0 disables the output buffer. Address: $0006 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 DDRC6 DDRC5 DDRC4 DDRC3 DDRC2 DDRC1 DDRC0 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 13-10. Data Direction Register C (DDRC) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 162 Freescale Semiconductor

Port C DDRC6–DDRC0 — Data Direction Register C Bits These read/write bits control port C data direction. Reset clears DDRC6–DDRC0, configuring all port C pins as inputs. 1 = Corresponding port C pin configured as output 0 = Corresponding port C pin configured as input NOTE Avoid glitches on port C pins by writing to the port C data register before changing data direction register C bits from 0 to 1. Figure 13-11 shows the port C I/O logic. READ DDRC ($0006) WRITE DDRC ($0006) S DDRCx U RESET B A T A D WRITE PTC ($0002) AL PTCx PTCx N R TE VDD N I PTCPUEx INTERNAL PULLUP READ PTC ($0002) DEVICE Figure 13-11. Port C I/O Circuit When bit DDRCx is a logic 1, reading address $0002 reads the PTCx data latch. When bit DDRCx is a logic 0, reading address $0002 reads the voltage level on the pin. The data latch can always be written, regardless of the state of its data direction bit. Table 13-4 summarizes the operation of the port C pins. Table 13-4. Port C Pin Functions PTCPUE DDRC PTC I/O Pin Accesses to DDRC Accesses to PTC Bit Bit Bit Mode Read/Write Read Write 1 0 X(1) Input, VDD(2) DDRC6–DDRC0 Pin PTC6–PTC0(3) 0 0 X Input, Hi-Z(4) DDRC6–DDRC0 Pin PTC6–PTC0(3) X 1 X Output DDRC6–DDRC0 PTC6–PTC0 PTC6–PTC0 1. X = Don’t care 2. I/O pin pulled up to V by internal pullup device. DD 3. Writing affects data register, but does not affect input. 4. Hi-Z = High impedance MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 163

Input/Output (I/O) Ports 13.5.3 Port C Input Pullup Enable Register The port C input pullup enable register (PTCPUE) contains a software configurable pullup device for each of the seven port C pins. Each bit is individually configurable and requires that the data direction register, DDRC, bit be configured as an input. Each pullup is automatically and dynamically disabled when a port bit’s DDRC is configured for output mode. Address: $000E Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 PTCPUE6 PTCPUE5 PTCPUE4 PTCPUE3 PTCPUE2 PTCPUE1 PTCPUE0 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 13-12. Port C Input Pullup Enable Register (PTCPUE) PTCPUE6–PTCPUE0 — Port C Input Pullup Enable Bits These writable bits are software programmable to enable pullup devices on an input port bit. 1 = Corresponding port C pin configured to have internal pullup 0 = Corresponding port C pin internal pullup disconnected 13.6 Port D Port D is an 8-bit special-function port that shares four of its pins with the serial peripheral interface (SPI) module and four of its pins with the two timer interface (TIM1 and TIM2) modules. Port D also has software configurable pullup devices if configured as an input port. 13.6.1 Port D Data Register The port D data register (PTD) contains a data latch for each of the eight port D pins. Address: $0003 Bit 7 6 5 4 3 2 1 Bit 0 Read: PTD7 PTD6 PTD5 PTD4 PTD3 PTD2 PTD1 PTD0 Write: Reset: Unaffected by reset Alternative T2CH1 T2CH0 T1CH1 T1CH0 SPSCK MOSI MISO SS Function: Figure 13-13. Port D Data Register (PTD) PTD7–PTD0 — Port D Data Bits These read/write bits are software-programmable. Data direction of each port D pin is under the control of the corresponding bit in data direction register D. Reset has no effect on port D data. T2CH1 and T2CH0 — Timer 2 Channel I/O Bits The PTD7/T2CH1–PTD6/T2CH0 pins are the TIM2 input capture/output compare pins. The edge/level select bits, ELSxB:ELSxA, determine whether the PTD7/T2CH1–PTD6/T2CH0 pins are timer channel I/O pins or general-purpose I/O pins. See Chapter 19 Timer Interface Module (TIM). MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 164 Freescale Semiconductor

Port D T1CH1 and T1CH0 — Timer 1 Channel I/O Bits The PTD7/T1CH1–PTD6/T1CH0 pins are the TIM1 input capture/output compare pins. The edge/level select bits, ELSxB and ELSxA, determine whether the PTD7/T1CH1–PTD6/T1CH0 pins are timer channel I/O pins or general-purpose I/O pins. See Chapter 19 Timer Interface Module (TIM). SPSCK — SPI Serial Clock The PTD3/SPSCK pin is the serial clock input of the SPI module. When the SPE bit is clear, the PTD3/SPSCK pin is available for general-purpose I/O. MOSI — Master Out/Slave In The PTD2/MOSI pin is the master out/slave in terminal of the SPI module. When the SPE bit is clear, the PTD2/MOSI pin is available for general-purpose I/O. MISO — Master In/Slave Out The PTD1/MISO pin is the master in/slave out terminal of the SPI module. When the SPI enable bit, SPE, is clear, the SPI module is disabled, and the PTD0/SS pin is available for general-purpose I/O. Data direction register D (DDRD) does not affect the data direction of port D pins that are being used by the SPI module. However, the DDRD bits always determine whether reading port D returns the states of the latches or the states of the pins. See Table 13-5. SS — Slave Select The PTD0/SS pin is the slave select input of the SPI module. When the SPE bit is clear, or when the SPI master bit, SPMSTR, is set, the PTD0/SS pin is available for general-purpose I/O. When the SPI is enabled, the DDRB0 bit in data direction register B (DDRB) has no effect on the PTD0/SS pin. 13.6.2 Data Direction Register D Data direction register D (DDRD) determines whether each port D pin is an input or an output. Writing a logic 1 to a DDRD bit enables the output buffer for the corresponding port D pin; a logic 0 disables the output buffer. Address: $0007 Bit 7 6 5 4 3 2 1 Bit 0 Read: DDRD7 DDRD6 DDRD5 DDRD4 DDRD3 DDRD2 DDRD1 DDRD0 Write: Reset: 0 0 0 0 0 0 0 0 Figure 13-14. Data Direction Register D (DDRD) DDRD7–DDRD0 — Data Direction Register D Bits These read/write bits control port D data direction. Reset clears DDRD7–DDRD0, configuring all port D pins as inputs. 1 = Corresponding port D pin configured as output 0 = Corresponding port D pin configured as input NOTE Avoid glitches on port D pins by writing to the port D data register before changing data direction register D bits from 0 to 1. Figure 13-15 shows the port D I/O logic. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 165

Input/Output (I/O) Ports READ DDRD ($0007) WRITE DDRD ($0007) DDRDx RESET S U B WRITE PTD ($0003) TA PTDx PTDx A D L A VDD N R E T IN PTDPUEx INTERNAL PULLUP READ PTD ($0003) DEVICE Figure 13-15. Port D I/O Circuit When bit DDRDx is a logic 1, reading address $0003 reads the PTDx data latch. When bit DDRDx is a logic 0, reading address $0003 reads the voltage level on the pin. The data latch can always be written, regardless of the state of its data direction bit. Table 13-5 summarizes the operation of the port D pins. Table 13-5. Port D Pin Functions PTDPUE DDRD PTD I/O Pin Accesses to DDRD Accesses to PTD Bit Bit Bit Mode Read/Write Read Write 1 0 X(1) Input, VDD(2) DDRD7–DDRD0 Pin PTD7–PTD0(3) 0 0 X Input, Hi-Z(4) DDRD7–DDRD0 Pin PTD7–PTD0(3) X 1 X Output DDRD7–DDRD0 PTD7–PTD0 PTD7–PTD0 1. X = Don’t care 2. I/O pin pulled up to V by internal pullup device. DD 3. Writing affects data register, but does not affect input. 4. Hi-Z = High impedance 13.6.3 Port D Input Pullup Enable Register The port D input pullup enable register (PTDPUE) contains a software configurable pullup device for each of the eight port D pins. Each bit is individually configurable and requires that the data direction register, DDRD, bit be configured as an input. Each pullup is automatically and dynamically disabled when a port bit’s DDRD is configured for output mode. Address: $000F Bit 7 6 5 4 3 2 1 Bit 0 Read: PTDPUE7 PTDPUE6 PTDPUE5 PTDPUE4 PTDPUE3 PTDPUE2 PTDPUE1 PTDPUE0 Write: Reset: 0 0 0 0 0 0 0 0 Figure 13-16. Port D Input Pullup Enable Register (PTDPUE) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 166 Freescale Semiconductor

Port E PTDPUE7–PTDPUE0 — Port D Input Pullup Enable Bits These writable bits are software programmable to enable pullup devices on an input port bit. 1 = Corresponding port D pin configured to have internal pullup 0 = Corresponding port D pin has internal pullup disconnected 13.7 Port E Port E is a 6-bit special-function port that shares two of its pins with the enhanced serial communications interface (ESCI) module. 13.7.1 Port E Data Register The port E data register contains a data latch for each of the six port E pins. Address: $0008 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 PTE5 PTE4 PTE3 PTE2 PTE1 PTE0 Write: Reset: Unaffected by reset Alternative RxD TxD Function: = Unimplemented Figure 13-17. Port E Data Register (PTE) PTE5-PTE0 — Port E Data Bits These read/write bits are software-programmable. Data direction of each port E pin is under the control of the corresponding bit in data direction register E. Reset has no effect on port E data. NOTE Data direction register E (DDRE) does not affect the data direction of port E pins that are being used by the ESCI module. However, the DDRE bits always determine whether reading port E returns the states of the latches or the states of the pins. See Table 13-6. RxD — SCI Receive Data Input The PTE1/RxD pin is the receive data input for the ESCI module. When the enable SCI bit, ENSCI, is clear, the ESCI module is disabled, and the PTE1/RxD pin is available for general-purpose I/O. See Chapter 15 Enhanced Serial Communications Interface (ESCI) Module. TxD — SCI Transmit Data Output The PTE0/TxD pin is the transmit data output for the ESCI module. When the enable SCI bit, ENSCI, is clear, the ESCI module is disabled, and the PTE0/TxD pin is available for general-purpose I/O. See Chapter 15 Enhanced Serial Communications Interface (ESCI) Module. 13.7.2 Data Direction Register E Data direction register E (DDRE) determines whether each port E pin is an input or an output. Writing a logic 1 to a DDRE bit enables the output buffer for the corresponding port E pin; a logic 0 disables the output buffer. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 167

Input/Output (I/O) Ports Address: $000C Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 DDRE5 DDRE4 DDRE3 DDRE2 DDRE1 DDRE0 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 13-18. Data Direction Register E (DDRE) DDRE5–DDRE0 — Data Direction Register E Bits These read/write bits control port E data direction. Reset clears DDRE5–DDRE0, configuring all port E pins as inputs. 1 = Corresponding port E pin configured as output 0 = Corresponding port E pin configured as input NOTE Avoid glitches on port E pins by writing to the port E data register before changing data direction register E bits from 0 to 1. Figure 13-19 shows the port E I/O logic. READ DDRE ($000C) WRITE DDRE ($000C) S DDREx BU RESET A T A D WRITE PTE ($0008) AL PTEx PTEx N R E T N I READ PTE ($0008) Figure 13-19. Port E I/O Circuit When bit DDREx is a logic 1, reading address $0008 reads the PTEx data latch. When bit DDREx is a logic 0, reading address $0008 reads the voltage level on the pin. The data latch can always be written, regardless of the state of its data direction bit. Table 13-6 summarizes the operation of the port E pins. Table 13-6. Port E Pin Functions DDRE PTE I/O Pin Accesses to DDRE Accesses to PTE Bit Bit Mode Read/Write Read Write 0 X(1) Input, Hi-Z(2) DDRE5–DDRE0 Pin PTE5–PTE0(3) 1 X Output DDRE5–DDRE0 PTE5–PTE0 PTE5–PTE0 1. X = Don’t care 2. Hi-Z = High impedance 3. Writing affects data register, but does not affect input. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 168 Freescale Semiconductor

Chapter 14 Resets and Interrupts 14.1 Introduction Resets and interrupts are responses to exceptional events during program execution. A reset re-initializes the microcontroller (MCU) to its startup condition. An interrupt vectors the program counter to a service routine. 14.2 Resets A reset immediately returns the MCU to a known startup condition and begins program execution from a user-defined memory location. 14.2.1 Effects A reset: (cid:129) Immediately stops the operation of the instruction being executed (cid:129) Initializes certain control and status bits (cid:129) Loads the program counter with a user-defined reset vector address from locations $FFFE and $FFFF (cid:129) Selects CGMXCLK divided by four as the bus clock 14.2.2 External Reset A logic 0 applied to the RST pin for a time, t , generates an external reset. An external reset sets the RL PIN bit in the system integration module (SIM) reset status register. 14.2.3 Internal Reset Sources: (cid:129) Power-on reset (POR) (cid:129) Computer operating properly (COP) (cid:129) Low-power reset circuits (cid:129) Illegal opcode (cid:129) Illegal address All internal reset sources pull the RST pin low for 32 CGMXCLK cycles to allow resetting of external devices. The MCU is held in reset for an additional 32 CGMXCLK cycles after releasing the RST pin. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 169

Resets and Interrupts 14.2.3.1 Power-On Reset (POR) A power-on reset (POR) is an internal reset caused by a positive transition on the V pin. V at the DD DD POR must go below V to reset the MCU. This distinguishes between a reset and a POR. The POR is POR not a brown-out detector, low-voltage detector, or glitch detector. A power-on reset: (cid:129) Holds the clocks to the central processor unit (CPU) and modules inactive for an oscillator stabilization delay of 4096 CGMXCLK cycles (cid:129) Drives the RST pin low during the oscillator stabilization delay (cid:129) Releases the RST pin 32 CGMXCLK cycles after the oscillator stabilization delay (cid:129) Releases the CPU to begin the reset vector sequence 64 CGMXCLK cycles after the oscillator stabilization delay (cid:129) Sets the POR and LVI bits in the SIM reset status register and clears all other bits in the register OSC1 PORRST(1) 4096 32 CYCLES CYCLES CGMXCLK CGMOUT RST PIN 1. PORRST is an internally generated power-on reset pulse. Figure 14-1. Power-On Reset Recovery 14.2.3.2 Computer Operating Properly (COP) Reset A computer operating properly (COP) reset is an internal reset caused by an overflow of the COP counter. A COP reset sets the COP bit in the SIM reset status register. To clear the COP counter and prevent a COP reset, write any value to the COP control register at location $FFFF. 14.2.3.3 Low-Voltage Inhibit (LVI) Reset A low-voltage inhibit (LVI) reset is an internal reset caused by a drop in the power supply voltage to the LVI voltage. TRIPF An LVI reset: (cid:129) Holds the clocks to the CPU and modules inactive for an oscillator stabilization delay of 4096 CGMXCLK cycles after the power supply voltage rises to the LVI voltage TRIPR (cid:129) Drives the RST pin low for as long as V is below the LVI voltage and during the oscillator DD TRIPR stabilization delay (cid:129) Releases the RST pin 32 CGMXCLK cycles after the oscillator stabilization delay (cid:129) Releases the CPU to begin the reset vector sequence 64 CGMXCLK cycles after the oscillator stabilization delay (cid:129) Sets the LVI bit in the SIM reset status register MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 170 Freescale Semiconductor

Resets 14.2.3.4 Illegal Opcode Reset An illegal opcode reset is an internal reset caused by an opcode that is not in the instruction set. An illegal opcode reset sets the ILOP bit in the SIM reset status register. If the stop enable bit, STOP, in the mask option register is a logic 0, the STOP instruction causes an illegal opcode reset. 14.2.3.5 Illegal Address Reset An illegal address reset is an internal reset caused by opcode fetch from an unmapped address. An illegal address reset sets the ILAD bit in the SIM reset status register. A data fetch from an unmapped address does not generate a reset. 14.2.4 System Integration Module (SIM) Reset Status Register This read-only register contains flags to show reset sources. All flag bits are automatically cleared following a read of the register. Reset service can read the SIM reset status register to clear the register after power-on reset and to determine the source of any subsequent reset. The register is initialized on power-up as shown with the POR bit set and all other bits cleared. During a POR or any other internal reset, the RST pin is pulled low. After the pin is released, it will be sampled 32 CGMXCLK cycles later. If the pin is not above a V at that time, then the PIN bit in the SRSR may be set IH in addition to whatever other bits are set. NOTE Only a read of the SIM reset status register clears all reset flags. After multiple resets from different sources without reading the register, multiple flags remain set. Address: $FE01 Bit 7 6 5 4 3 2 1 Bit 0 Read: POR PIN COP ILOP ILAD MODRST LVI 0 Write: POR: 1 0 0 0 0 0 0 0 =Unimplemented Figure 14-2. SIM Reset Status Register (SRSR) POR — Power-On Reset Flag 1 = Power-on reset since last read of SRSR 0 = Read of SRSR since last power-on reset PIN — External Reset Flag 1 = External reset via RST pin since last read of SRSR 0 = POR or read of SRSR since last external reset COP — Computer Operating Properly Reset Bit 1 = Last reset caused by timeout of COP counter 0 = POR or read of SRSR since any reset ILOP — Illegal Opcode Reset Bit 1 = Last reset caused by an illegal opcode 0 = POR or read of SRSR since any reset MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 171

Resets and Interrupts ILAD — Illegal Address Reset Bit 1 = Last reset caused by an opcode fetch from an illegal address 0 = POR or read of SRSR since any reset MODRST — Monitor Mode Entry Module Reset Bit 1 = Last reset caused by forced monitor mode entry. 0 = POR or read of SRSR since any reset LVI — Low-Voltage Inhibit Reset Bit 1 = Last reset caused by low-power supply voltage 0 = POR or read of SRSR since any reset 14.3 Interrupts An interrupt temporarily changes the sequence of program execution to respond to a particular event. An interrupt does not stop the operation of the instruction being executed, but begins when the current instruction completes its operation. 14.3.1 Effects An interrupt: (cid:129) Saves the CPU registers on the stack. At the end of the interrupt, the RTI instruction recovers the CPU registers from the stack so that normal processing can resume. (cid:129) Sets the interrupt mask (I bit) to prevent additional interrupts. Once an interrupt is latched, no other interrupt can take precedence, regardless of its priority. (cid:129) Loads the program counter with a user-defined vector address (cid:129) (cid:129) (cid:129) 5 CONDITION CODE REGISTER 1 4 ACCUMULATOR 2 STACKING 3 INDEX REGISTER (LOW BYTE)(1) 3 UNSTACKING ORDER 2 PROGRAM COUNTER (HIGH BYTE) 4 ORDER 1 PROGRAM COUNTER (LOW BYTE) 5 (cid:129) (cid:129) (cid:129) $00FF DEFAULT ADDRESS ON RESET 1. High byte of index register is not stacked. Figure 14-3. Interrupt Stacking Order MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 172 Freescale Semiconductor

Interrupts After every instruction, the CPU checks all pending interrupts if the I bit is not set. If more than one interrupt is pending when an instruction is done, the highest priority interrupt is serviced first. In the example shown in Figure 14-4, if an interrupt is pending upon exit from the interrupt service routine, the pending interrupt is serviced before the LDA instruction is executed. CLI LDA #$FF BACKGROUND ROUTINE INT1 PSHH INT1 INTERRUPT SERVICE ROUTINE PULH RTI INT2 PSHH INT2 INTERRUPT SERVICE ROUTINE PULH RTI Figure 14-4. Interrupt Recognition Example The LDA opcode is prefetched by both the INT1 and INT2 RTI instructions. However, in the case of the INT1 RTI prefetch, this is a redundant operation. NOTE To maintain compatibility with the M6805 Family, the H register is not pushed on the stack during interrupt entry. If the interrupt service routine modifies the H register or uses the indexed addressing mode, save the H register and then restore it prior to exiting the routine. See Figure 14-5 for a flowchart depicting interrupt processing. 14.3.2 Sources The sources in Table 14-1 can generate CPU interrupt requests. 14.3.2.1 Software Interrupt (SWI) Instruction The software interrupt (SWI) instruction causes a non-maskable interrupt. NOTE A software interrupt pushes PC onto the stack. An SWI does not push PC – 1, as a hardware interrupt does. 14.3.2.2 Break Interrupt The break module causes the CPU to execute an SWI instruction at a software-programmable break point. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 173

Resets and Interrupts FROM RESET BREAK YES INTERRUPT ? NO YES II BBIITT SSEETT?? NO IRQ YES INTERRUPT ? NO CGM YES INTERRUPT ? NO OTHER YES INTERRUPTS ? NO STACK CPU REGISTERS SET I BIT LOAD PC WITH INTERRUPT VECTOR FETCH NEXT INSTRUCTION SWI YES INSTRUCTION ? NO RTI YES INSTRUCTION UNSTACK CPU REGISTERS ? NO EXECUTE INSTRUCTION Figure 14-5. Interrupt Processing MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 174 Freescale Semiconductor

Interrupts Table 14-1. Inte rrupt Sources INT Register Vector Source Flag Mask(1) Priority(2) Flag Address Reset None None None 0 $FFFE–$FFFF SWI instruction None None None 0 $FFFC–$FFFD IRQ pin IRQF IMASK1 IF1 1 $FFFA–$FFFB CGM change in lock PLLF PLLIE IF2 2 $FFF8–$FFF9 TIM1 channel 0 CH0F CH0IE IF3 3 $FFF6–$FFF7 TIM1 channel 1 CH1F CH1IE IF4 4 $FFF4–$FFF5 TIM1 overflow TOF TOIE IF5 5 $FFF2–$FFF3 TIM2 channel 0 CH0F CH0IE IF6 6 $FFF0–$FFF1 TIM2 channel 1 CH1F CH1IE IF7 7 $FFEE–$FFEF TIM2 overflow TOF TOIE IF8 8 $FFEC–$FFED SPI receiver full SPRF SPRIE SPI overflow OVRF ERRIE IF9 9 $FFEA–$FFEB SPI mode fault MODF ERRIE SPI transmitter empty SPTE SPTIE IF10 10 $FFE8–$FFE9 SCI receiver overrun OR ORIE SCI noise flag NF NEIE IF11 11 $FFE6–$FFE7 SCI framing error FE FEIE SCI parity error PE PEIE SCI receiver full SCRF SCRIE IF12 12 $FFE4–$FFE5 SCI input idle IDLE ILIE SCI transmitter empty SCTE SCTIE IF13 13 $FFE2–$FFE3 SCI transmission complete TC TCIE Keyboard pin KEYF IMASKK IF14 14 $FFE0–$FFE1 ADC conversion complete COCO AIEN IF15 15 $FFDE–$FFDF Timebase TBIF TBIE IF16 16 $FFDC–$FFDD MSCAN08 receiver wakeup WUPIF WUPIE IF17 17 $FFDA–$FFDB RWRNIF RWRNIE TWRNIF TWRNIE RERIF RERRIE MSCAN08 error IF18 18 $FFD8–$FFD9 TERRIF TERRIE BOFFIF BOFFIE OVRIF OVRIE MSCAN08 receiver RXF RXFIE IF19 19 $FFD6–$FFD7 TXE2 TXEIE2 MSCAN08 transmitter TXE1 TXEIE1 IF20 20 $FFD4–$FFD5 TXE0 TXEIE0 1. The I bit in the condition code register is a global mask for all interrupt sources except the SWI instruction. 2. 0 = highest priority MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 175

Resets and Interrupts 14.3.2.3 IRQ Pin A logic 0 on the IRQ1 pin latches an external interrupt request. 14.3.2.4 Clock Generator (CGM) The CGM can generate a CPU interrupt request every time the phase-locked loop circuit (PLL) enters or leaves the locked state. When the LOCK bit changes state, the PLL flag (PLLF) is set. The PLL interrupt enable bit (PLLIE) enables PLLF CPU interrupt requests. LOCK is in the PLL bandwidth control register. PLLF is in the PLL control register. 14.3.2.5 Timer Interface Module 1 (TIM1) TIM1 CPU interrupt sources: (cid:129) TIM1 overflow flag (TOF) — The TOF bit is set when the TIM1 counter value rolls over to $0000 after matching the value in the TIM1 counter modulo registers. The TIM1 overflow interrupt enable bit, TOIE, enables TIM1 overflow CPU interrupt requests. TOF and TOIE are in the TIM1 status and control register. (cid:129) TIM1 channel flags (CH1F–CH0F) — The CHxF bit is set when an input capture or output compare occurs on channel x. The channel x interrupt enable bit, CHxIE, enables channel x TIM1 CPU interrupt requests. CHxF and CHxIE are in the TIM1 channel x status and control register. 14.3.2.6 Timer Interface Module 2 (TIM2) TIM2 CPU interrupt sources: (cid:129) TIM2 overflow flag (TOF) — The TOF bit is set when the TIM2 counter value rolls over to $0000 after matching the value in the TIM2 counter modulo registers. The TIM2 overflow interrupt enable bit, TOIE, enables TIM2 overflow CPU interrupt requests. TOF and TOIE are in the TIM2 status and control register. (cid:129) TIM2 channel flags (CH1F–CH0F) — The CHxF bit is set when an input capture or output compare occurs on channel x. The channel x interrupt enable bit, CHxIE, enables channel x TIM2 CPU interrupt requests. CHxF and CHxIE are in the TIM2 channel x status and control register. 14.3.2.7 Serial Peripheral Interface (SPI) SPI CPU interrupt sources: (cid:129) SPI receiver full bit (SPRF) — The SPRF bit is set every time a byte transfers from the shift register to the receive data register. The SPI receiver interrupt enable bit, SPRIE, enables SPRF CPU interrupt requests. SPRF is in the SPI status and control register and SPRIE is in the SPI control register. (cid:129) SPI transmitter empty (SPTE) — The SPTE bit is set every time a byte transfers from the transmit data register to the shift register. The SPI transmit interrupt enable bit, SPTIE, enables SPTE CPU interrupt requests. SPTE is in the SPI status and control register and SPTIE is in the SPI control register. (cid:129) Mode fault bit (MODF) — The MODF bit is set in a slave SPI if the SS pin goes high during a transmission with the mode fault enable bit (MODFEN) set. In a master SPI, the MODF bit is set if the SS pin goes low at any time with the MODFEN bit set. The error interrupt enable bit, ERRIE, enables MODF CPU interrupt requests. MODF, MODFEN, and ERRIE are in the SPI status and control register. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 176 Freescale Semiconductor

Interrupts (cid:129) Overflow bit (OVRF) — The OVRF bit is set if software does not read the byte in the receive data register before the next full byte enters the shift register. The error interrupt enable bit, ERRIE, enables OVRF CPU interrupt requests. OVRF and ERRIE are in the SPI status and control register. 14.3.2.8 Serial Communications Interface (SCI) SCI CPU interrupt sources: (cid:129) SCI transmitter empty bit (SCTE) — SCTE is set when the SCI data register transfers a character to the transmit shift register. The SCI transmit interrupt enable bit, SCTIE, enables transmitter CPU interrupt requests. SCTE is in SCI status register 1. SCTIE is in SCI control register 2. (cid:129) Transmission complete bit (TC) — TC is set when the transmit shift register and the SCI data register are empty and no break or idle character has been generated. The transmission complete interrupt enable bit, TCIE, enables transmitter CPU interrupt requests. TC is in SCI status register 1. TCIE is in SCI control register 2. (cid:129) SCI receiver full bit (SCRF) — SCRF is set when the receive shift register transfers a character to the SCI data register. The SCI receive interrupt enable bit, SCRIE, enables receiver CPU interrupts. SCRF is in SCI status register 1. SCRIE is in SCI control register 2. (cid:129) Idle input bit (IDLE) — IDLE is set when 10 or 11 consecutive logic 1s shift in from the RxD pin. The idle line interrupt enable bit, ILIE, enables IDLE CPU interrupt requests. IDLE is in SCI status register 1. ILIE is in SCI control register 2. (cid:129) Receiver overrun bit (OR) — OR is set when the receive shift register shifts in a new character before the previous character was read from the SCI data register. The overrun interrupt enable bit, ORIE, enables OR to generate SCI error CPU interrupt requests. OR is in SCI status register 1. ORIE is in SCI control register 3. (cid:129) Noise flag (NF) — NF is set when the SCI detects noise on incoming data or break characters, including start, data, and stop bits. The noise error interrupt enable bit, NEIE, enables NF to generate SCI error CPU interrupt requests. NF is in SCI status register 1. NEIE is in SCI control register 3. (cid:129) Framing error bit (FE) — FE is set when a logic 0 occurs where the receiver expects a stop bit. The framing error interrupt enable bit, FEIE, enables FE to generate SCI error CPU interrupt requests. FE is in SCI status register 1. FEIE is in SCI control register 3. (cid:129) Parity error bit (PE) — PE is set when the SCI detects a parity error in incoming data. The parity error interrupt enable bit, PEIE, enables PE to generate SCI error CPU interrupt requests. PE is in SCI status register 1. PEIE is in SCI control register 3. 14.3.2.9 KBD0–KBD7 Pins A logic 0 on a keyboard interrupt pin latches an external interrupt request. 14.3.2.10 Analog-to-Digital Converter (ADC) When the AIEN bit is set, the ADC module is capable of generating a CPU interrupt after each ADC conversion. The COCO bit is not used as a conversion complete flag when interrupts are enabled. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 177

Resets and Interrupts 14.3.2.11 Timebase Module (TBM) The timebase module can interrupt the CPU on a regular basis with a rate defined by TBR2–TBR0. When the timebase counter chain rolls over, the TBIF flag is set. If the TBIE bit is set, enabling the timebase interrupt, the counter chain overflow will generate a CPU interrupt request. Interrupts must be acknowledged by writing a logic 1 to the TACK bit. 14.3.2.12 MSCAN MSCAN08 interrupt sources: (cid:129) MSCAN08 transmitter empty bits (TXE0–TXE2) — The TXEx bit is set when the corresponding MSCAN08 data buffer is empty. The MSCAN08 transmit interrupt enable bits, TXEIE0–TXEIE2, enables transmitter CPU interrupt requests. TXEx is in MSCAN08 transmitter flag register. TXEIEx is in MSCAN08 transmitter control register. (cid:129) MSCAN08 receiver full bit (RXF) — The RXF bit is set when the a MSCAN08 message has been successfully received and loaded into the foreground receive buffer. The MSCAN08 receive interrupt enable bit, RXFIE, enables receiver CPU interrupt requests. RXF is in MSCAN08 receiver flag register. RXFIE is in MSCAN08 receiver interrupt enable register. (cid:129) MSCAN08 wakeup bit (WUPIF) — WUPIF is set when activity on the CAN bus occurred during the MSCAN08 internal sleep mode. The wakeup interrupt enable bit, WUPIE, enables MSCAN08 wakeup CPU interrupt requests. WUPIF is in MSCAN08 receiver flag register. WUPIE is in MSCAN08 receiver interrupt enable register. (cid:129) Overrun bit (OVRIF) — OVRIF is set when both the foreground and the background receive message buffers are filled with correctly received messages and a further message is being received from the bus. The overrun interrupt enable bit, OVRIE, enables OVRIF to generate MSCAN08 error CPU interrupt requests. OVRIF is in MSCAN08 receiver flag register. OVRIE is in MSCAN08 receiver interrupt enable register. (cid:129) Receiver Warning bit (RWRNIF) — RWRNIF is set when the receive error counter has reached the CPU warning limit of 96. The receiver warning interrupt enable bit, RWRNIE, enables RWRNIF to generate MSCAN08 error CPU interrupt requests. RWRNIF is in MSCAN08 receiver flag register. RWRNIE is in MSCAN08 receiver interrupt enable register. (cid:129) Transmitter Warning bit (TWRNIF) — TWRNIF is set when the transmit error counter has reached the CPU warning limit of 96. The transmitter warning interrupt enable bit, TWRNIF, enables TWRNIF to generate MSCAN08 error CPU interrupt requests. TWRNIF is in MSCAN08 receiver flag register. TWRNIE is in MSCAN08 receiver interrupt enable register. (cid:129) Receiver Error Passive bit (RERRIF) — RERRIF is set when the receive error counter has exceeded the error passive limit of 127 and the MSCAN08 has gone to error passive state. The receiver error passive interrupt enable bit, RERRIE, enables RERRIF to generate MSCAN08 error CPU interrupt requests. RERRIF is in MSCAN08 receiver flag register. RERRIE is in MSCAN08 receiver interrupt enable register. (cid:129) Transmitter Error Passive bit (TERRIF) — TERRIF is set when the transmit error counter has exceeded the error passive limit of 127 and the MSCAN08 has gone to error passive state. The transmit error passive interrupt enable bit, TERRIE, enables TERRIF to generate MSCAN08 error CPU interrupt requests. TERRIF is in MSCAN08 receiver flag register. TERRIE is in MSCAN08 receiver interrupt enable register. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 178 Freescale Semiconductor

Interrupts (cid:129) Bus Off bit (BOFFIF) — BOFFIF is set when the transmit error counter has exceeded 255 and MSCAN08 has gone to bus off state. The bus off interrupt enable bit, BOFFIE, enables BOFFIF to generate MSCAN08 error CPU interrupt requests. BOFFIF is in MSCAN08 receiver flag register. BOFFIE is in MSCAN08 receiver interrupt enable register. 14.3.3 Interrupt Status Registers The flags in the interrupt status registers identify maskable interrupt sources. Table 14-2 summarizes the interrupt sources and the interrupt status register flags that they set. The interrupt status registers can be useful for debugging. Table 14-2. Interrupt Source Flags Interrupt Interrupt Status Source Register Flag Reset — SWI instruction — IRQ pin IF1 CGM change of lock IF2 TIM1 channel 0 IF3 TIM1 channel 1 IF4 TIM1 overflow IF5 TIM2 channel 0 IF6 TIM2 channel 1 IF7 TIM2 overflow IF8 SPI receive IF9 SPI transmit IF10 SCI error IF11 SCI receive IF12 SCI transmit IF13 Keyboard IF14 ADC conversion complete IF15 Timebase IF16 MSCAN08 wakeup IF17 MSCAN08 error IF18 MSCAN08 receive IF19 MSCAN08 transmit IF20 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 179

Resets and Interrupts 14.3.3.1 Interrupt Status Register 1 Address: $FE04 Bit 7 6 5 4 3 2 1 Bit 0 Read: IF6 IF5 IF4 IF3 IF2 IF1 0 0 Write: R R R R R R R R Reset: 0 0 0 0 0 0 0 0 R = Reserved Figure 14-6. Interrupt Status Register 1 (INT1) IF6–IF1 — Interrupt Flags 6–1 These flags indicate the presence of interrupt requests from the sources shown in Table 14-2. 1 = Interrupt request present 0 = No interrupt request present Bit 1 and Bit 0 — Always read 0 14.3.3.2 Interrupt Status Register 2 Address: $FE05 Bit 7 6 5 4 3 2 1 Bit 0 Read: IF14 IF13 IF12 IF11 IF10 IF9 IF8 IF7 Write: R R R R R R R R Reset: 0 0 0 0 0 0 0 0 R = Reserved Figure 14-7. Interrupt Status Register 2 (INT2) IF14–IF7 — Interrupt Flags 14–7 These flags indicate the presence of interrupt requests from the sources shown in Table 14-2. 1 = Interrupt request present 0 = No interrupt request present 14.3.3.3 Interrupt Status Register 3 Address: $FE06 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 IF20 IF19 IF18 IF17 IF16 IF15 Write: R R R R R R R R Reset: 0 0 0 0 0 0 0 0 R = Reserved Figure 14-8. Interrupt Status Register 3 (INT3) IF20–IF15 — Interrupt Flags 20–15 This flag indicates the presence of an interrupt request from the source shown in Table 14-2. 1 = Interrupt request present 0 = No interrupt request present Bits 7–6 — Always read 0 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 180 Freescale Semiconductor

Chapter 15 Enhanced Serial Communications Interface (ESCI) Module 15.1 Introduction The enhanced serial communications interface (ESCI) module allows asynchronous communications with peripheral devices and other microcontroller units (MCU). 15.2 Features Features include: (cid:129) Full-duplex operation (cid:129) Standard mark/space non-return-to-zero (NRZ) format (cid:129) Programmable baud rates (cid:129) Programmable 8-bit or 9-bit character length (cid:129) Separately enabled transmitter and receiver (cid:129) Separate receiver and transmitter central processor unit (CPU) interrupt requests (cid:129) Programmable transmitter output polarity (cid:129) Two receiver wakeup methods: – Idle line wakeup – Address mark wakeup (cid:129) Interrupt-driven operation with eight interrupt flags: – Transmitter empty – Transmission complete – Receiver full – Idle receiver input – Receiver overrun – Noise error – Framing error – Parity error (cid:129) Receiver framing error detection (cid:129) Hardware parity checking (cid:129) 1/16 bit-time noise detection MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 181

Enhanced Serial Communications Interface (ESCI) Module INTERNAL BUS M68HC08 CPU REGCISPTUERS ARITUHNMIET T(AICL/ULO)GIC PROGRAMMMOADBULLEE TIMEBASE DDRA PORTA PPTTAA70//KKBBDD70–(1) PTB7/AD7 SINGLE BREAKPOINT CONTROL AND STATUS REGISTERS — 64 BYTES PTB6/AD6 BREAK MODULE PTB5/AD5 USER FLASH — 15,872 BYTES LOWD-UVAOLL TVAOGLETA INGHEIBIT DDRB PORTB PPTTBB43//AADD43 MODULE PTB2/AD2 USER RAM — 1024 BYTES PTB1/AD1 8-BIT KEYBOARD PTB0/AD0 MONITOR ROM — 350 BYTES INTERRUPT MODULE PTC6(1) PTC5(1) FLASH PROGRAMMING ROUTINES ROM — 406 BYTES 2-CHANNEL TIMER USER FLASH VECTOR SPACE — 44 BYTES INTERFACE MODULE 1 DDRC PORTC PPPTTTCCC432(((111))),,, (((222))) 2-CHANNEL TIMER INTERFACE MODULE 2 PTC1/CANRX(1), (2) CLOCK GENERATOR MODULE PTC0/CAN (1), (2) TX OSC1 1–8 MHz OSCILLATOR ENHANCED SERIAL OSC2 COMUNICATIONS PTD7/T2CH1(1) PHASE LOCKED LOOP INTERFACE MODULE PTD6/T2CH0(1) CGMXFC PTD5/T1CH1(1) RST(3) SYSTEM INTEGRATION COPMRPOUPTEERRL YO MPEORDAUTLIENG DDRD PORTD PPPTTTDDD243///MTS1POCSSHCI(0K1()(11)) MODULE SERIAL PERIPHERAL PTD1/MISO(1) INTERFACE MODULE PTD0/SS(1) IRQ(3) SINGLE EXTERNAL INTERRUPT MODULE PTE5–PTE2 VVDDAD//VVREFH 10-CBOITN AVNEARLTOEGR- TMOO-DDUIGLIETAL MONITOR MODULE DDRE PORTE PPTTEE10//RTxxDD DDAD REFL MEMORY MAP MODULE POWER-ON RESET MODULE SECURITY CONFIGURATION MODULE VDD REGISTER 1–2 VSS POWER MODULE V DDA V MONITOR MODE ENTRY SSA MSCAN08 MODULE MODULE 1. Ports are software configurable with pullup device if input port. 2. Higher current drive port pins 3. Pin contains integrated pullup device Figure 15-1. Block Diagram Highlighting ESCI Block and Pins MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 182 Freescale Semiconductor

Pin Name Conventions 15.3 Pin Name Conventions The generic names of the ESCI input/output (I/O) pins are: (cid:129) RxD (receive data) (cid:129) TxD (transmit data) ESCI I/O lines are implemented by sharing parallel I/O port pins. The full name of an ESCI input or output reflects the name of the shared port pin. Table 15-1 shows the full names and the generic names of the ESCI I/O pins. The generic pin names appear in the text of this section. Table 15-1. Pin Name Conventions Generic Pin Names RxD TxD Full Pin Names PTE1/RxD PTE0/TxD 15.4 Functional Description Figure 15-2 shows the structure of the ESCI module. The ESCI allows full-duplex, asynchronous, NRZ serial communication between the MCU and remote devices, including other MCUs. The transmitter and receiver of the ESCI operate independently, although they use the same baud rate generator. During normal operation, the CPU monitors the status of the ESCI, writes the data to be transmitted, and processes received data. The baud rate clock source for the ESCI can be selected via the configuration bit, ESCIBDSRC, of the CONFIG2 register ($001E). For reference, a summary of the ESCI module input/output registers is provided in Figure 15-3. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 183

Enhanced Serial Communications Interface (ESCI) Module INTERNAL BUS ESCI DATA ESCI DATA REGISTER REGISTER RxD R RxD SHIFRTE RCEEGIVISETER TRANSMITTEINTERRUPTCONTROL RECEIVERINTERRUPTCONTROL ERRORINTERRUPTCONTROL SHITFRT ARNESGMISITTER SCI_TxD ER TxD LINR TXINV BUS_CLK BIT R A SCTIE R8 TCIE SL T8 SCRIE ILIE ACLK BIT TE IN SCIACTL SCTE RE TC RWU SCRF OR ORIE SBK K IDLE NF NEIE CL _ FE FEIE SCI PE PEIE LOOPS LOOPS ENSCI WAKEUP RECEIVE FLAG TRANSMIT CONTROL CONTROL CONTROL CONTROL M BUS ENSCI BKF LINT CLOCK RPF WAKE ENHANCED ILTY PRESCALER CGMXCLK PRE- BAUD RATE PEN ÷ 4 SCALER GENERATOR SL PTY C BDSRMFIG2 ÷ 16 DATCAO SNETLREOCLTION CION SRO EFC SL = 1 -> SCI_CLK = BUSCLK SL = 0 -> SCI_CLK = CGMSCLK (4x BUSCLK) Figure 15-2. ESCI Module Block Diagram MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 184 Freescale Semiconductor

Functional Description Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: ESCI Prescaler Register PDS2 PDS1 PDS0 PSSB4 PSSB3 PSSB2 PSSB1 PSSB0 $0009 (SCPSC) Write: See page 206. Reset: 0 0 0 0 0 0 0 0 Read: ALOST AFIN ARUN AROVFL ARD8 ESCI Arbiter Control AM1 AM0 ACLK $000A Register (SCIACTL) Write: See page 209. Reset: 0 0 0 0 0 0 0 0 Read: ARD7 ARD6 ARD5 ARD4 ARD3 ARD2 ARD1 ARD0 ESCI Arbiter Data $000B Register (SCIADAT) Write: See page 210. Reset: 0 0 0 0 0 0 0 0 Read: ESCI Control Register 1 LOOPS ENSCI TXINV M WAKE ILTY PEN PTY $0013 (SCC1) Write: See page 196. Reset: 0 0 0 0 0 0 0 0 Read: ESCI Control Register 2 SCTIE TCIE SCRIE ILIE TE RE RWU SBK $0014 (SCC2) Write: See page 198. Reset: 0 0 0 0 0 0 0 0 Read: R8 ESCI Control Register 3 T8 R R ORIE NEIE FEIE PEIE $0015 (SCC3) Write: See page 200. Reset: U 0 0 0 0 0 0 0 Read: SCTE TC SCRF IDLE OR NF FE PE ESCI Status Register 1 $0016 (SCS1) Write: See page 201. Reset: 1 1 0 0 0 0 0 0 Read: 0 0 0 0 0 0 BKF RPF ESCI Status Register 2 $0017 (SCS2) Write: See page 203. Reset: 0 0 0 0 0 0 0 0 Read: R7 R6 R5 R4 R3 R2 R1 R0 ESCI Data Register $0018 (SCDR) Write: T7 T6 T5 T4 T3 T2 T1 T0 See page 204. Reset: Unaffected by reset Read: ESCI Baud Rate Register LINT LINR SCP1 SCP0 R SCR2 SCR1 SCR0 $0019 (SCBR) Write: See page 204. Reset: 0 0 0 0 0 0 0 0 =Unimplemented R = Reserved U = Unaffected Figure 15-3. ESCI I/O Register Summary MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 185

Enhanced Serial Communications Interface (ESCI) Module 15.4.1 Data Format The SCI uses the standard non-return-to-zero mark/space data format illustrated in Figure 15-4. PARITY 8-BIT DATA FORMAT OR DATA NEXT START (BIT M IN SCC1 CLEAR) BIT START BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 STOP BIT BIT PARITY 9-BIT DATA FORMAT OR DATA NEXT START (BIT M IN SCC1 SET) BIT START BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 8 STOP BIT BIT Figure 15-4. SCI Data Formats 15.4.2 Transmitter Figure 15-5 shows the structure of the SCI transmitter and the registers are summarized in Figure 15-3. The baud rate clock source for the ESCI can be selected via the configuration bit, ESCIBDSRC. INTERNAL BUS PRE- BAUD ÷ 4 ÷ 16 ESCI DATA REGISTER SCALER DIVIDER SCP1 11-BIT T SCP0 OP TRANSMIT AR T SHIFT REGISTER T SCR1 S S H 8 7 6 5 4 3 2 1 0 L SCI_TxD SCR2 SCR0 B EST TXINV MS R U PRE-SCALE PT REQ M U R BUS CLOCK PPPPSDDDSSSSB1204 SMITTER CPU INTER PPETNY GENPAETRR8IATTYION LOAD FROM SCDR SHIFT ENABLE PREAMBLE(ALL ONES) BREAK(ALL ZEROS) PSSB3 AN R TRANSMITTER T PSSB2 CONTROL LOGIC PSSB1 PSSB0 SCTE SBK SCTE LOOPS SCTIE SCTIE ENSCI TC TC TE TCIE TCIE LINT Figure 15-5. ESCI Transmitter MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 186 Freescale Semiconductor

Functional Description 15.4.2.1 Character Length The transmitter can accommodate either 8-bit or 9-bit data. The state of the M bit in ESCI control register 1 (SCC1) determines character length. When transmitting 9-bit data, bit T8 in ESCI control register 3 (SCC3) is the ninth bit (bit 8). 15.4.2.2 Character Transmission During an ESCI transmission, the transmit shift register shifts a character out to the TxD pin. The ESCI data register (SCDR) is the write-only buffer between the internal data bus and the transmit shift register. To initiate an ESCI transmission: 1. Enable the ESCI by writing a logic 1 to the enable ESCI bit (ENSCI) in ESCI control register 1 (SCC1). 2. Enable the transmitter by writing a logic 1 to the transmitter enable bit (TE) in ESCI control register 2 (SCC2). 3. Clear the ESCI transmitter empty bit (SCTE) by first reading ESCI status register 1 (SCS1) and then writing to the SCDR. For 9-bit data, also write the T8 bit in SCC3. 4. Repeat step 3 for each subsequent transmission. At the start of a transmission, transmitter control logic automatically loads the transmit shift register with a preamble of logic 1s. After the preamble shifts out, control logic transfers the SCDR data into the transmit shift register. A logic 0 start bit automatically goes into the least significant bit (LSB) position of the transmit shift register. A logic 1 stop bit goes into the most significant bit (MSB) position. The ESCI transmitter empty bit, SCTE, in SCS1 becomes set when the SCDR transfers a byte to the transmit shift register. The SCTE bit indicates that the SCDR can accept new data from the internal data bus. If the ESCI transmit interrupt enable bit, SCTIE, in SCC2 is also set, the SCTE bit generates a transmitter CPU interrupt request. When the transmit shift register is not transmitting a character, the TxD pin goes to the idle condition, logic 1. If at any time software clears the ENSCI bit in ESCI control register 1 (SCC1), the transmitter and receiver relinquish control of the port E pins. 15.4.2.3 Break Characters Writing a logic 1 to the send break bit, SBK, in SCC2 loads the transmit shift register with a break character. For TXINV = 0 (output not inverted), a transmitted break character contains all logic 0s and has no start, stop, or parity bit. Break character length depends on the M bit in SCC1 and the LINR bits in SCBR. As long as SBK is at logic 1, transmitter logic continuously loads break characters into the transmit shift register. After software clears the SBK bit, the shift register finishes transmitting the last break character and then transmits at least one logic 1. The automatic logic 1 at the end of a break character guarantees the recognition of the start bit of the next character. When LINR is cleared in SCBR, the ESCI recognizes a break character when a start bit is followed by eight or nine logic 0 data bits and a logic 0 where the stop bit should be, resulting in a total of 10 or 11 consecutive logic 0 data bits. When LINR is set in SCBR, the ESCI recognizes a break character when a start bit is followed by 9 or 10 logic 0 data bits and a logic 0 where the stop bit should be, resulting in a total of 11 or 12 consecutive logic 0 data bits. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 187

Enhanced Serial Communications Interface (ESCI) Module Receiving a break character has these effects on ESCI registers: (cid:129) Sets the framing error bit (FE) in SCS1 (cid:129) Sets the ESCI receiver full bit (SCRF) in SCS1 (cid:129) Clears the ESCI data register (SCDR) (cid:129) Clears the R8 bit in SCC3 (cid:129) Sets the break flag bit (BKF) in SCS2 (cid:129) May set the overrun (OR), noise flag (NF), parity error (PE), or reception in progress flag (RPF) bits 15.4.2.4 Idle Characters For TXINV = 0 (output not inverted), a transmitted idle character contains all logic 1s and has no start, stop, or parity bit. Idle character length depends on the M bit in SCC1. The preamble is a synchronizing idle character that begins every transmission. If the TE bit is cleared during a transmission, the TxD pin becomes idle after completion of the transmission in progress. Clearing and then setting the TE bit during a transmission queues an idle character to be sent after the character currently being transmitted. NOTE When a break sequence is followed immediately by an idle character, this SCI design exhibits a condition in which the break character length is reduced by one half bit time. In this instance, the break sequence will consist of a valid start bit, eight or nine bits (as defined by the M bit in SCC1) of logic 0 and one half data bit length of logic 0 in the stop bit position followed immediately by the idle character. To ensure a break character of the proper length is transmitted, always queue up a byte of data to be transmitted while the final break sequence is in progress. NOTE When queueing an idle character, return the TE bit to logic 1 before the stop bit of the current character shifts out to the TxD pin. Setting TE after the stop bit appears on TxD causes data previously written to the SCDR to be lost. A good time to toggle the TE bit for a queued idle character is when the SCTE bit becomes set and just before writing the next byte to the SCDR. 15.4.2.5 Inversion of Transmitted Output The transmit inversion bit (TXINV) in ESCI control register 1 (SCC1) reverses the polarity of transmitted data. All transmitted values including idle, break, start, and stop bits, are inverted when TXINV is at logic 1. See 15.8.1 ESCI Control Register 1. 15.4.2.6 Transmitter Interrupts These conditions can generate CPU interrupt requests from the ESCI transmitter: (cid:129) ESCI transmitter empty (SCTE) — The SCTE bit in SCS1 indicates that the SCDR has transferred a character to the transmit shift register. SCTE can generate a transmitter CPU interrupt request. Setting the ESCI transmit interrupt enable bit, SCTIE, in SCC2 enables the SCTE bit to generate transmitter CPU interrupt requests. (cid:129) Transmission complete (TC) — The TC bit in SCS1 indicates that the transmit shift register and the SCDR are empty and that no break or idle character has been generated. The transmission complete interrupt enable bit, TCIE, in SCC2 enables the TC bit to generate transmitter CPU interrupt requests. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 188 Freescale Semiconductor

Functional Description 15.4.3 Receiver Figure 15-6 shows the structure of the ESCI receiver. The receiver I/O registers are summarized in Figure 15-3. INTERNAL BUS LINR SCR1 SCP1 SCR2 ESCI DATA REGISTER SCP0 SCR0 ÷ 4 PRE- BAUD ÷ 16 SCALER DIVIDER P 11-BIT RT O A T RECEIVE SHIFT REGISTER T S S R DATA RE-ALE RxD RECOVERY H 8 7 6 5 4 3 2 1 0 L PC S ALL ZEROS ES BKF N CLOCK PPDDSS12 RPF ALL O MSB S BU PDS0 M PSSB4 SCRF RWU WAKE WAKEUP PSSB3 IDLE ILTY LOGIC PSSB2 PSSB1 PEN PARITY R8 PSSB0 PTY CHECKING IDLE ILIE ILIE SCRF SCRIE SCRIE T P RUST RE EU U INTREQ P C OR OR ORIE ORIE EST NF NF CPUEQU NEIE NEIE RROR RUPT R FE FE ETER FEIE FEIE N I PE PE PEIE PEIE Figure 15-6. ESCI Receiver Block Diagram MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 189

Enhanced Serial Communications Interface (ESCI) Module 15.4.3.1 Character Length The receiver can accommodate either 8-bit or 9-bit data. The state of the M bit in ESCI control register 1 (SCC1) determines character length. When receiving 9-bit data, bit R8 in ESCI control register 3 (SCC3) is the ninth bit (bit 8). When receiving 8-bit data, bit R8 is a copy of the eighth bit (bit 7). 15.4.3.2 Character Reception During an ESCI reception, the receive shift register shifts characters in from the RxD pin. The ESCI data register (SCDR) is the read-only buffer between the internal data bus and the receive shift register. After a complete character shifts into the receive shift register, the data portion of the character transfers to the SCDR. The ESCI receiver full bit, SCRF, in ESCI status register 1 (SCS1) becomes set, indicating that the received byte can be read. If the ESCI receive interrupt enable bit, SCRIE, in SCC2 is also set, the SCRF bit generates a receiver CPU interrupt request. 15.4.3.3 Data Sampling The receiver samples the RxD pin at the RT clock rate. The RT clock is an internal signal with a frequency 16 times the baud rate. To adjust for baud rate mismatch, the RT clock is resynchronized at these times (see Figure 15-7): (cid:129) After every start bit (cid:129) After the receiver detects a data bit change from logic 1 to logic 0 (after the majority of data bit samples at RT8, RT9, and RT10 returns a valid logic 1 and the majority of the next RT8, RT9, and RT10 samples returns a valid logic 0) To locate the start bit, data recovery logic does an asynchronous search for a logic 0 preceded by three logic 1s. When the falling edge of a possible start bit occurs, the RT clock begins to count to 16. START BIT LSB RxD START BIT START BIT DATA SAMPLES QUALIFICATION VERIFICATION SAMPLING RT CLOCK RT CLOCK 1 1 1 1 1 1 1 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 STATE RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT RT CLOCK RESET Figure 15-7. Receiver Data Sampling To verify the start bit and to detect noise, data recovery logic takes samples at RT3, RT5, and RT7. Table 15-2 summarizes the results of the start bit verification samples. Table 15-2. Start Bit Verification RT3, RT5, and RT7 Samples Start Bit Verification Noise Flag 000 Yes 0 001 Yes 1 010 Yes 1 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 190 Freescale Semiconductor

Functional Description Table 15-2. Start Bit Verification (Continued) RT3, RT5, and RT7 Samples Start Bit Verification Noise Flag 011 No 0 100 Yes 1 101 No 0 110 No 0 111 No 0 If start bit verification is not successful, the RT clock is reset and a new search for a start bit begins. To determine the value of a data bit and to detect noise, recovery logic takes samples at RT8, RT9, and RT10. Table 15-3 summarizes the results of the data bit samples. Table 15-3. Data Bit Recovery RT8, RT9, and RT10 Samples Data Bit Determination Noise Flag 000 0 0 001 0 1 010 0 1 011 1 1 100 0 1 101 1 1 110 1 1 111 1 0 NOTE The RT8, RT9, and RT10 samples do not affect start bit verification. If any or all of the RT8, RT9, and RT10 start bit samples are logic 1s following a successful start bit verification, the noise flag (NF) is set and the receiver assumes that the bit is a start bit. To verify a stop bit and to detect noise, recovery logic takes samples at RT8, RT9, and RT10. Table 15-4 summarizes the results of the stop bit samples. Table 15-4. Stop Bit Recovery RT8, RT9, and RT10 Samples Framing Error Flag Noise Flag 000 1 0 001 1 1 010 1 1 011 0 1 100 1 1 101 0 1 110 0 1 111 0 0 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 191

Enhanced Serial Communications Interface (ESCI) Module 15.4.3.4 Framing Errors If the data recovery logic does not detect a logic 1 where the stop bit should be in an incoming character, it sets the framing error bit, FE, in SCS1. A break character also sets the FE bit because a break character has no stop bit. The FE bit is set at the same time that the SCRF bit is set. 15.4.3.5 Baud Rate Tolerance A transmitting device may be operating at a baud rate below or above the receiver baud rate. Accumulated bit time misalignment can cause one of the three stop bit data samples to fall outside the actual stop bit. Then a noise error occurs. If more than one of the samples is outside the stop bit, a framing error occurs. In most applications, the baud rate tolerance is much more than the degree of misalignment that is likely to occur. As the receiver samples an incoming character, it resynchronizes the RT clock on any valid falling edge within the character. Resynchronization within characters corrects misalignments between transmitter bit times and receiver bit times. Slow Data Tolerance Figure 15-8 shows how much a slow received character can be misaligned without causing a noise error or a framing error. The slow stop bit begins at RT8 instead of RT1 but arrives in time for the stop bit data samples at RT8, RT9, and RT10. MSB STOP RECEIVER RT CLOCK 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 T T T T T T T T T 1 1 1 1 1 1 1 R R R R R R R R R T T T T T T T R R R R R R R DATA SAMPLES Figure 15-8. Slow Data For an 8-bit character, data sampling of the stop bit takes the receiver 9 bit times× 16 RT cycles + 10 RT cycles = 154 RT cycles. With the misaligned character shown in Figure 15-8, the receiver counts 154 RT cycles at the point when the count of the transmitting device is 9 bit times × 16 RT cycles + 3 RT cycles = 147 RT cycles. The maximum percent difference between the receiver count and the transmitter count of a slow 8-bit character with no errors is: 154–147 -------------------------- ×100 = 4.54% 154 For a 9-bit character, data sampling of the stop bit takes the receiver10 bit times × 16 RT cycles + 10 RT cycles = 170 RT cycles. With the misaligned character shown in Figure 15-8, the receiver counts 170 RT cycles at the point when the count of the transmitting device is 10 bit times × 16 RT cycles + 3 RT cycles = 163 RT cycles. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 192 Freescale Semiconductor

Functional Description The maximum percent difference between the receiver count and the transmitter count of a slow 9-bit character with no errors is: 170–163 -------------------------- ×100 = 4.12% 170 Fast Data Tolerance Figure 15-9 shows how much a fast received character can be misaligned without causing a noise error or a framing error. The fast stop bit ends at RT10 instead of RT16 but is still there for the stop bit data samples at RT8, RT9, and RT10. STOP IDLE OR NEXT CHARACTER RECEIVER RT CLOCK 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 T T T T T T T T T 1 1 1 1 1 1 1 R R R R R R R R R T T T T T T T R R R R R R R DATA SAMPLES Figure 15-9. Fast Data For an 8-bit character, data sampling of the stop bit takes the receiver9 bit times× 16 RT cycles + 10 RT cycles = 154 RT cycles. With the misaligned character shown in Figure 15-9, the receiver counts 154 RT cycles at the point when the count of the transmitting device is 10 bit times × 16 RT cycles = 160 RT cycles. The maximum percent difference between the receiver count and the transmitter count of a fast 8-bit character with no errors is 154–160 -------------------------- ×100 = 3.90%. 154 For a 9-bit character, data sampling of the stop bit takes the receiver 10 bit times× 16 RT cycles + 10 RT cycles = 170 RT cycles. With the misaligned character shown in Figure 15-9, the receiver counts 170 RT cycles at the point when the count of the transmitting device is 11 bit times × 16 RT cycles = 176 RT cycles. The maximum percent difference between the receiver count and the transmitter count of a fast 9-bit character with no errors is: 170–176 -------------------------- ×100 = 3.53%. 170 15.4.3.6 Receiver Wakeup So that the MCU can ignore transmissions intended only for other receivers in multiple-receiver systems, the receiver can be put into a standby state. Setting the receiver wakeup bit, RWU, in SCC2 puts the receiver into a standby state during which receiver interrupts are disabled. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 193

Enhanced Serial Communications Interface (ESCI) Module Depending on the state of the WAKE bit in SCC1, either of two conditions on the RxD pin can bring the receiver out of the standby state: 1. Address mark — An address mark is a logic 1 in the MSB position of a received character. When the WAKE bit is set, an address mark wakes the receiver from the standby state by clearing the RWU bit. The address mark also sets the ESCI receiver full bit, SCRF. Software can then compare the character containing the address mark to the user-defined address of the receiver. If they are the same, the receiver remains awake and processes the characters that follow. If they are not the same, software can set the RWU bit and put the receiver back into the standby state. 2. Idle input line condition — When the WAKE bit is clear, an idle character on the RxD pin wakes the receiver from the standby state by clearing the RWU bit. The idle character that wakes the receiver does not set the receiver idle bit, IDLE, or the ESCI receiver full bit, SCRF. The idle line type bit, ILTY, determines whether the receiver begins counting logic 1s as idle character bits after the start bit or after the stop bit. NOTE With the WAKE bit clear, setting the RWU bit after the RxD pin has been idle will cause the receiver to wake up. 15.4.3.7 Receiver Interrupts These sources can generate CPU interrupt requests from the ESCI receiver: (cid:129) ESCI receiver full (SCRF) — The SCRF bit in SCS1 indicates that the receive shift register has transferred a character to the SCDR. SCRF can generate a receiver CPU interrupt request. Setting the ESCI receive interrupt enable bit, SCRIE, in SCC2 enables the SCRF bit to generate receiver CPU interrupts. (cid:129) Idle input (IDLE) — The IDLE bit in SCS1 indicates that 10 or 11 consecutive logic 1s shifted in from the RxD pin. The idle line interrupt enable bit, ILIE, in SCC2 enables the IDLE bit to generate CPU interrupt requests. 15.4.3.8 Error Interrupts These receiver error flags in SCS1 can generate CPU interrupt requests: (cid:129) Receiver overrun (OR) — The OR bit indicates that the receive shift register shifted in a new character before the previous character was read from the SCDR. The previous character remains in the SCDR, and the new character is lost. The overrun interrupt enable bit, ORIE, in SCC3 enables OR to generate ESCI error CPU interrupt requests. (cid:129) Noise flag (NF) — The NF bit is set when the ESCI detects noise on incoming data or break characters, including start, data, and stop bits. The noise error interrupt enable bit, NEIE, in SCC3 enables NF to generate ESCI error CPU interrupt requests. (cid:129) Framing error (FE) — The FE bit in SCS1 is set when a logic 0 occurs where the receiver expects a stop bit. The framing error interrupt enable bit, FEIE, in SCC3 enables FE to generate ESCI error CPU interrupt requests. (cid:129) Parity error (PE) — The PE bit in SCS1 is set when the ESCI detects a parity error in incoming data. The parity error interrupt enable bit, PEIE, in SCC3 enables PE to generate ESCI error CPU interrupt requests. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 194 Freescale Semiconductor

Low-Power Modes 15.5 Low-Power Modes The WAIT and STOP instructions put the MCU in low power-consumption standby modes. 15.5.1 Wait Mode The ESCI module remains active in wait mode. Any enabled CPU interrupt request from the ESCI module can bring the MCU out of wait mode. If ESCI module functions are not required during wait mode, reduce power consumption by disabling the module before executing the WAIT instruction. 15.5.2 Stop Mode The ESCI module is inactive in stop mode. The STOP instruction does not affect ESCI register states. ESCI module operation resumes after the MCU exits stop mode. Because the internal clock is inactive during stop mode, entering stop mode during an ESCI transmission or reception results in invalid data. 15.6 ESCI During Break Module Interrupts The BCFE bit in the break flag control register (SBFCR) enables software to clear status bits during the break state. See Chapter 20 Development Support. To allow software to clear status bits during a break interrupt, write a logic 1 to the BCFE bit. If a status bit is cleared during the break state, it remains cleared when the MCU exits the break state. To protect status bits during the break state, write a logic 0 to the BCFE bit. With BCFE at logic 0 (its default state), software can read and write I/O registers during the break state without affecting status bits. Some status bits have a two-step read/write clearing procedure. If software does the first step on such a bit before the break, the bit cannot change during the break state as long as BCFE is at logic 0. After the break, doing the second step clears the status bit. 15.7 I/O Signals Port E shares two of its pins with the ESCI module. The two ESCI I/O pins are: (cid:129) PTE0/TxD — transmit data (cid:129) PTE1/RxD — receive data 15.7.1 PTE0/TxD (Transmit Data) The PTE0/TxD pin is the serial data output from the ESCI transmitter. The ESCI shares the PTE0/TxD pin with port E. When the ESCI is enabled, the PTE0/TxD pin is an output regardless of the state of the DDRE0 bit in data direction register E (DDRE). 15.7.2 PTE1/RxD (Receive Data) The PTE1/RxD pin is the serial data input to the ESCI receiver. The ESCI shares the PTE1/RxD pin with port E. When the ESCI is enabled, the PTE1/RxD pin is an input regardless of the state of the DDRE1 bit in data direction register E (DDRE). MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 195

Enhanced Serial Communications Interface (ESCI) Module 15.8 I/O Registers These I/O registers control and monitor ESCI operation: (cid:129) ESCI control register 1, SCC1 (cid:129) ESCI control register 2, SCC2 (cid:129) ESCI control register 3, SCC3 (cid:129) ESCI status register 1, SCS1 (cid:129) ESCI status register 2, SCS2 (cid:129) ESCI data register, SCDR (cid:129) ESCI baud rate register, SCBR (cid:129) ESCI prescaler register, SCPSC (cid:129) ESCI arbiter control register, SCIACTL (cid:129) ESCI arbiter data register, SCIADAT 15.8.1 ESCI Control Register 1 ESCI control register 1 (SCC1): (cid:129) Enables loop mode operation (cid:129) Enables the ESCI (cid:129) Controls output polarity (cid:129) Controls character length (cid:129) Controls ESCI wakeup method (cid:129) Controls idle character detection (cid:129) Enables parity function (cid:129) Controls parity type Address: $0013 Bit 7 6 5 4 3 2 1 Bit 0 Read: LOOPS ENSCI TXINV M WAKE ILTY PEN PTY Write: Reset: 0 0 0 0 0 0 0 0 Figure 15-10. ESCI Control Register 1 (SCC1) LOOPS — Loop Mode Select Bit This read/write bit enables loop mode operation. In loop mode the RxD pin is disconnected from the ESCI, and the transmitter output goes into the receiver input. Both the transmitter and the receiver must be enabled to use loop mode. Reset clears the LOOPS bit. 1 = Loop mode enabled 0 = Normal operation enabled ENSCI — Enable ESCI Bit This read/write bit enables the ESCI and the ESCI baud rate generator. Clearing ENSCI sets the SCTE and TC bits in ESCI status register 1 and disables transmitter interrupts. Reset clears the ENSCI bit. 1 = ESCI enabled 0 = ESCI disabled MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 196 Freescale Semiconductor

I/O Registers TXINV — Transmit Inversion Bit This read/write bit reverses the polarity of transmitted data. Reset clears the TXINV bit. 1 = Transmitter output inverted 0 = Transmitter output not inverted NOTE Setting the TXINV bit inverts all transmitted values including idle, break, start, and stop bits. M — Mode (Character Length) Bit This read/write bit determines whether ESCI characters are eight or nine bits long (See Table 15-5).The ninth bit can serve as a receiver wakeup signal or as a parity bit. Reset clears the M bit. 1 = 9-bit ESCI characters 0 = 8-bit ESCI characters Table 15-5. Character Format Selection Control Bits Character Format M PEN:PTY Start Bits Data Bits Parity Stop Bits Character Length 0 0 X 1 8 None 1 10 bits 1 0 X 1 9 None 1 11 bits 0 1 0 1 7 Even 1 10 bits 0 1 1 1 7 Odd 1 10 bits 1 1 0 1 8 Even 1 11 bits 1 1 1 1 8 Odd 1 11 bits WAKE — Wakeup Condition Bit This read/write bit determines which condition wakes up the ESCI: a logic 1 (address mark) in the MSB position of a received character or an idle condition on the RxD pin. Reset clears the WAKE bit. : 1 = Address mark wakeup 0 = Idle line wakeup ILTY — Idle Line Type Bit This read/write bit determines when the ESCI starts counting logic 1s as idle character bits. The counting begins either after the start bit or after the stop bit. If the count begins after the start bit, then a string of logic 1s preceding the stop bit may cause false recognition of an idle character. Beginning the count after the stop bit avoids false idle character recognition, but requires properly synchronized transmissions. Reset clears the ILTY bit. 1 = Idle character bit count begins after stop bit 0 = Idle character bit count begins after start bit PEN — Parity Enable Bit This read/write bit enables the ESCI parity function (see Table 15-5). When enabled, the parity function inserts a parity bit in the MSB position (see Table 15-3). Reset clears the PEN bit. 1 = Parity function enabled 0 = Parity function disabled MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 197

Enhanced Serial Communications Interface (ESCI) Module PTY — Parity Bit This read/write bit determines whether the ESCI generates and checks for odd parity or even parity (see Table 15-5). Reset clears the PTY bit. 1 = Odd parity 0 = Even parity NOTE Changing the PTY bit in the middle of a transmission or reception can generate a parity error. 15.8.2 ESCI Control Register 2 ESCI control register 2 (SCC2): (cid:129) Enables these CPU interrupt requests: – SCTE bit to generate transmitter CPU interrupt requests – TC bit to generate transmitter CPU interrupt requests – SCRF bit to generate receiver CPU interrupt requests – IDLE bit to generate receiver CPU interrupt requests (cid:129) Enables the transmitter (cid:129) Enables the receiver (cid:129) Enables ESCI wakeup (cid:129) Transmits ESCI break characters Address: $0014 Bit 7 6 5 4 3 2 1 Bit 0 Read: SCTIE TCIE SCRIE ILIE TE RE RWU SBK Write: Reset: 0 0 0 0 0 0 0 0 Figure 15-11. ESCI Control Register 2 (SCC2) SCTIE — ESCI Transmit Interrupt Enable Bit This read/write bit enables the SCTE bit to generate ESCI transmitter CPU interrupt requests. Setting the SCTIE bit in SCC2 enables the SCTE bit to generate CPU interrupt requests. Reset clears the SCTIE bit. 1 = SCTE enabled to generate CPU interrupt 0 = SCTE not enabled to generate CPU interrupt TCIE — Transmission Complete Interrupt Enable Bit This read/write bit enables the TC bit to generate ESCI transmitter CPU interrupt requests. Reset clears the TCIE bit. 1 = TC enabled to generate CPU interrupt requests 0 = TC not enabled to generate CPU interrupt requests SCRIE — ESCI Receive Interrupt Enable Bit This read/write bit enables the SCRF bit to generate ESCI receiver CPU interrupt requests. Setting the SCRIE bit in SCC2 enables the SCRF bit to generate CPU interrupt requests. Reset clears the SCRIE bit. 1 = SCRF enabled to generate CPU interrupt 0 = SCRF not enabled to generate CPU interrupt MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 198 Freescale Semiconductor

I/O Registers ILIE — Idle Line Interrupt Enable Bit This read/write bit enables the IDLE bit to generate ESCI receiver CPU interrupt requests. Reset clears the ILIE bit. 1 = IDLE enabled to generate CPU interrupt requests 0 = IDLE not enabled to generate CPU interrupt requests TE — Transmitter Enable Bit Setting this read/write bit begins the transmission by sending a preamble of 10 or 11 logic 1s from the transmit shift register to the TxD pin. If software clears the TE bit, the transmitter completes any transmission in progress before the TxD returns to the idle condition (logic 1). Clearing and then setting TE during a transmission queues an idle character to be sent after the character currently being transmitted. Reset clears the TE bit. 1 = Transmitter enabled 0 = Transmitter disabled NOTE Writing to the TE bit is not allowed when the enable ESCI bit (ENSCI) is clear. ENSCI is in ESCI control register 1. RE — Receiver Enable Bit Setting this read/write bit enables the receiver. Clearing the RE bit disables the receiver but does not affect receiver interrupt flag bits. Reset clears the RE bit. 1 = Receiver enabled 0 = Receiver disabled NOTE Writing to the RE bit is not allowed when the enable ESCI bit (ENSCI) is clear. ENSCI is in ESCI control register 1. RWU — Receiver Wakeup Bit This read/write bit puts the receiver in a standby state during which receiver interrupts are disabled. The WAKE bit in SCC1 determines whether an idle input or an address mark brings the receiver out of the standby state and clears the RWU bit. Reset clears the RWU bit. 1 = Standby state 0 = Normal operation SBK — Send Break Bit Setting and then clearing this read/write bit transmits a break character followed by a logic 1. The logic 1 after the break character guarantees recognition of a valid start bit. If SBK remains set, the transmitter continuously transmits break characters with no logic 1s between them. Reset clears the SBK bit. 1 = Transmit break characters 0 = No break characters being transmitted NOTE Do not toggle the SBK bit immediately after setting the SCTE bit. Toggling SBK before the preamble begins causes the ESCI to send a break character instead of a preamble. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 199

Enhanced Serial Communications Interface (ESCI) Module 15.8.3 ESCI Control Register 3 ESCI control register 3 (SCC3): (cid:129) Stores the ninth ESCI data bit received and the ninth ESCI data bit to be transmitted. (cid:129) Enables these interrupts: – Receiver overrun – Noise error – Framing error – Parity error Address: $0015 Bit 7 6 5 4 3 2 1 Bit 0 Read: R8 T8 R R ORIE NEIE FEIE PEIE Write: Reset: U 0 0 0 0 0 0 0 =Unimplemented R =Reserved U = Unaffected Figure 15-12. ESCI Control Register 3 (SCC3) R8 — Received Bit 8 When the ESCI is receiving 9-bit characters, R8 is the read-only ninth bit (bit 8) of the received character. R8 is received at the same time that the SCDR receives the other 8 bits. When the ESCI is receiving 8-bit characters, R8 is a copy of the eighth bit (bit 7). Reset has no effect on the R8 bit. T8 — Transmitted Bit 8 When the ESCI is transmitting 9-bit characters, T8 is the read/write ninth bit (bit 8) of the transmitted character. T8 is loaded into the transmit shift register at the same time that the SCDR is loaded into the transmit shift register. Reset clears the T8 bit. ORIE — Receiver Overrun Interrupt Enable Bit This read/write bit enables ESCI error CPU interrupt requests generated by the receiver overrun bit, OR. Reset clears ORIE. 1 = ESCI error CPU interrupt requests from OR bit enabled 0 = ESCI error CPU interrupt requests from OR bit disabled NEIE — Receiver Noise Error Interrupt Enable Bit This read/write bit enables ESCI error CPU interrupt requests generated by the noise error bit, NE. Reset clears NEIE. 1 = ESCI error CPU interrupt requests from NE bit enabled 0 = ESCI error CPU interrupt requests from NE bit disabled FEIE — Receiver Framing Error Interrupt Enable Bit This read/write bit enables ESCI error CPU interrupt requests generated by the framing error bit, FE. Reset clears FEIE. 1 = ESCI error CPU interrupt requests from FE bit enabled 0 = ESCI error CPU interrupt requests from FE bit disabled PEIE — Receiver Parity Error Interrupt Enable Bit This read/write bit enables ESCI receiver CPU interrupt requests generated by the parity error bit, PE. Reset clears PEIE. 1 = ESCI error CPU interrupt requests from PE bit enabled 0 = ESCI error CPU interrupt requests from PE bit disabled MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 200 Freescale Semiconductor

I/O Registers 15.8.4 ESCI Status Register 1 ESCI status register 1 (SCS1) contains flags to signal these conditions: (cid:129) Transfer of SCDR data to transmit shift register complete (cid:129) Transmission complete (cid:129) Transfer of receive shift register data to SCDR complete (cid:129) Receiver input idle (cid:129) Receiver overrun (cid:129) Noisy data (cid:129) Framing error (cid:129) Parity error Address: $0016 Bit 7 6 5 4 3 2 1 Bit 0 Read: SCTE TC SCRF IDLE OR NF FE PE Write: Reset: 1 1 0 0 0 0 0 0 =Unimplemented Figure 15-13. ESCI Status Register 1 (SCS1) SCTE — ESCI Transmitter Empty Bit This clearable, read-only bit is set when the SCDR transfers a character to the transmit shift register. SCTE can generate an ESCI transmitter CPU interrupt request. When the SCTIE bit in SCC2 is set, SCTE generates an ESCI transmitter CPU interrupt request. In normal operation, clear the SCTE bit by reading SCS1 with SCTE set and then writing to SCDR. Reset sets the SCTE bit. 1 = SCDR data transferred to transmit shift register 0 = SCDR data not transferred to transmit shift register TC — Transmission Complete Bit This read-only bit is set when the SCTE bit is set, and no data, preamble, or break character is being transmitted. TC generates an ESCI transmitter CPU interrupt request if the TCIE bit in SCC2 is also set. TC is cleared automatically when data, preamble, or break is queued and ready to be sent. There may be up to 1.5 transmitter clocks of latency between queueing data, preamble, and break and the transmission actually starting. Reset sets the TC bit. 1 = No transmission in progress 0 = Transmission in progress SCRF — ESCI Receiver Full Bit This clearable, read-only bit is set when the data in the receive shift register transfers to the ESCI data register. SCRF can generate an ESCI receiver CPU interrupt request. When the SCRIE bit in SCC2 is set the SCRF generates a CPU interrupt request. In normal operation, clear the SCRF bit by reading SCS1 with SCRF set and then reading the SCDR. Reset clears SCRF. 1 = Received data available in SCDR 0 = Data not available in SCDR IDLE — Receiver Idle Bit This clearable, read-only bit is set when 10 or 11 consecutive logic 1s appear on the receiver input. IDLE generates an ESCI receiver CPU interrupt request if the ILIE bit in SCC2 is also set. Clear the IDLE bit by reading SCS1 with IDLE set and then reading the SCDR. After the receiver is enabled, it MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 201

Enhanced Serial Communications Interface (ESCI) Module must receive a valid character that sets the SCRF bit before an idle condition can set the IDLE bit. Also, after the IDLE bit has been cleared, a valid character must again set the SCRF bit before an idle condition can set the IDLE bit. Reset clears the IDLE bit. 1 = Receiver input idle 0 = Receiver input active (or idle since the IDLE bit was cleared) OR — Receiver Overrun Bit This clearable, read-only bit is set when software fails to read the SCDR before the receive shift register receives the next character. The OR bit generates an ESCI error CPU interrupt request if the ORIE bit in SCC3 is also set. The data in the shift register is lost, but the data already in the SCDR is not affected. Clear the OR bit by reading SCS1 with OR set and then reading the SCDR. Reset clears the OR bit. 1 = Receive shift register full and SCRF = 1 0 = No receiver overrun Software latency may allow an overrun to occur between reads of SCS1 and SCDR in the flag-clearing sequence. Figure 15-14 shows the normal flag-clearing sequence and an example of an overrun caused by a delayed flag-clearing sequence. The delayed read of SCDR does not clear the OR bit because OR was not set when SCS1 was read. Byte 2 caused the overrun and is lost. The next flag-clearing sequence reads byte 3 in the SCDR instead of byte 2. In applications that are subject to software latency or in which it is important to know which byte is lost due to an overrun, the flag-clearing routine can check the OR bit in a second read of SCS1 after reading the data register. NORMAL FLAG CLEARING SEQUENCE 1 0 1 0 1 0 = = = = = = F F F F F F R R R R R R C C C C C C S S S S S S BYTE 1 BYTE 2 BYTE 3 BYTE 4 READ SCS1 READ SCS1 READ SCS1 SCRF = 1 SCRF = 1 SCRF = 1 OR = 0 OR = 0 OR = 0 READ SCDR READ SCDR READ SCDR BYTE 1 BYTE 2 BYTE 3 DELAYED FLAG CLEARING SEQUENCE SCRF = 1 SCRF = 1OR = 1 SCRF = 0OR = 1 SCRF = 1OR = 1 SCRF = 0OR = 0 BYTE 1 BYTE 2 BYTE 3 BYTE 4 READ SCS1 READ SCS1 SCRF = 1 SCRF = 1 OR = 0 OR = 1 READ SCDR READ SCDR BYTE 1 BYTE 3 Figure 15-14. Flag Clearing Sequence MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 202 Freescale Semiconductor

I/O Registers NF — Receiver Noise Flag Bit This clearable, read-only bit is set when the ESCI detects noise on the RxD pin. NF generates an NF CPU interrupt request if the NEIE bit in SCC3 is also set. Clear the NF bit by reading SCS1 and then reading the SCDR. Reset clears the NF bit. 1 = Noise detected 0 = No noise detected FE — Receiver Framing Error Bit This clearable, read-only bit is set when a logic 0 is accepted as the stop bit. FE generates an ESCI error CPU interrupt request if the FEIE bit in SCC3 also is set. Clear the FE bit by reading SCS1 with FE set and then reading the SCDR. Reset clears the FE bit. 1 = Framing error detected 0 = No framing error detected PE — Receiver Parity Error Bit This clearable, read-only bit is set when the ESCI detects a parity error in incoming data. PE generates a PE CPU interrupt request if the PEIE bit in SCC3 is also set. Clear the PE bit by reading SCS1 with PE set and then reading the SCDR. Reset clears the PE bit. 1 = Parity error detected 0 = No parity error detected 15.8.5 ESCI Status Register 2 ESCI status register 2 (SCS2) contains flags to signal these conditions: (cid:129) Break character detected (cid:129) Incoming data Address: $0017 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 0 0 BKF RPF Write: Reset: 0 0 0 0 0 0 0 0 =Unimplemented Figure 15-15. ESCI Status Register 2 (SCS2) BKF — Break Flag Bit This clearable, read-only bit is set when the ESCI detects a break character on the RxD pin. In SCS1, the FE and SCRF bits are also set. In 9-bit character transmissions, the R8 bit in SCC3 is cleared. BKF does not generate a CPU interrupt request. Clear BKF by reading SCS2 with BKF set and then reading the SCDR. Once cleared, BKF can become set again only after logic 1s again appear on the RxD pin followed by another break character. Reset clears the BKF bit. 1 = Break character detected 0 = No break character detected RPF — Reception in Progress Flag Bit This read-only bit is set when the receiver detects a logic 0 during the RT1 time period of the start bit search. RPF does not generate an interrupt request. RPF is reset after the receiver detects false start bits (usually from noise or a baud rate mismatch), or when the receiver detects an idle character. Polling RPF before disabling the ESCI module or entering stop mode can show whether a reception is in progress. 1 = Reception in progress 0 = No reception in progress MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 203

Enhanced Serial Communications Interface (ESCI) Module 15.8.6 ESCI Data Register The ESCI data register (SCDR) is the buffer between the internal data bus and the receive and transmit shift registers. Reset has no effect on data in the ESCI data register. Address: $0018 Bit 7 6 5 4 3 2 1 Bit 0 Read: R7 R6 R5 R4 R3 R2 R1 R0 Write: T7 T6 T5 T4 T3 T2 T1 T0 Reset: Unaffected by reset Figure 15-16. ESCI Data Register (SCDR) R7/T7:R0/T0 — Receive/Transmit Data Bits Reading address $0018 accesses the read-only received data bits, R7:R0. Writing to address $0018 writes the data to be transmitted, T7:T0. Reset has no effect on the ESCI data register. NOTE Do not use read-modify-write instructions on the ESCI data register. 15.8.7 ESCI Baud Rate Register The ESCI baud rate register (SCBR) together with the ESCI prescaler register selects the baud rate for both the receiver and the transmitter. NOTE There are two prescalers available to adjust the baud rate. One in the ESCI baud rate register and one in the ESCI prescaler register. Address: $0019 Bit 7 6 5 4 3 2 1 Bit 0 Read: LINT LINR SCP1 SCP0 R SCR2 SCR1 SCR0 Write: Reset: 0 0 0 0 0 0 0 0 R = Reserved Figure 15-17. ESCI Baud Rate Register (SCBR) LINT — LIN Transmit Enable This read/write bit selects the enhanced ESCI features for the local interconnect network (LIN) protocol as shown in Table 15-6. Reset clears LINT. LINR — LIN Receiver Bits This read/write bit selects the enhanced ESCI features for the local interconnect network (LIN) protocol as shown in Table 15-6. Reset clears LINR. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 204 Freescale Semiconductor

I/O Registers Table 15-6. ESCI LIN Control Bits LINT LINR M Functionality 0 0 X Normal ESCI functionality 0 1 0 13-bit break detect enabled for LIN receiver 0 1 1 14-bit break detect enabled for LIN receiver 1 0 0 13-bit generation enabled for LIN transmitter 1 0 1 14-bit generation enabled for LIN transmitter 1 1 0 13-bit break detect/11-bit generation enabled for LIN 1 1 1 14-bit break detect/12-bit generation enabled for LIN In LIN (version 1.2) systems, the master node transmits a break character which will appear as 11.05–14.95 dominant bits to the slave node. A data character of 0x00 sent from the master might appear as 7.65–10.35 dominant bit times. This is due to the oscillator tolerance requirement that the slave node must be within ±15% of the master node's oscillator. Since a slave node cannot know if it is running faster or slower than the master node (prior to synchronization), the LINR bit allows the slave node to differentiate between a 0x00 character of 10.35 bits and a break character of 11.05 bits. The break symbol length must be verified in software in any case, but the LINR bit serves as a filter, preventing false detections of break characters that are really 0x00 data characters. SCP1 and SCP0 — ESCI Baud Rate Register Prescaler Bits These read/write bits select the baud rate register prescaler divisor as shown in Table 15-7. Reset clears SCP1 and SCP0. Table 15-7. ESCI Baud Rate Prescaling Baud Rate Register SCP[1:0] Prescaler Divisor (BPD) 0 0 1 0 1 3 1 0 4 1 1 13 SCR2–SCR0 — ESCI Baud Rate Select Bits These read/write bits select the ESCI baud rate divisor as shown in Table 15-8. Reset clears SCR2–SCR0. Table 15-8. ESCI Baud Rate Selection SCR[2:1:0] Baud Rate Divisor (BD) 0 0 0 1 0 0 1 2 0 1 0 4 0 1 1 8 1 0 0 16 1 0 1 32 1 1 0 64 1 1 1 128 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 205

Enhanced Serial Communications Interface (ESCI) Module 15.8.8 ESCI Prescaler Register The ESCI prescaler register (SCPSC) together with the ESCI baud rate register selects the baud rate for both the receiver and the transmitter. NOTE There are two prescalers available to adjust the baud rate. One in the ESCI baud rate register and one in the ESCI prescaler register. Address: $0009 Bit 7 6 5 4 3 2 1 Bit 0 Read: PDS2 PDS1 PDS0 PSSB4 PSSB3 PSSB2 PSSB1 PSSB0 Write: Reset: 0 0 0 0 0 0 0 0 Figure 15-18. ESCI Prescaler Register (SCPSC) PDS2–PDS0 — Prescaler Divisor Select Bits These read/write bits select the prescaler divisor as shown in Table 15-9. Reset clears PDS2–PDS0. NOTE The setting of ‘000’ will bypass this prescaler. It is not recommended to bypass the prescaler while ENSCI is set, because the switching is not glitch free. Table 15-9. ESCI Prescaler Division Ratio PS[2:1:0] Prescaler Divisor (PD) 0 0 0 Bypass this prescaler 0 0 1 2 0 1 0 3 0 1 1 4 1 0 0 5 1 0 1 6 1 1 0 7 1 1 1 8 PSSB4–PSSB0 — Clock Insertion Select Bits These read/write bits select the number of clocks inserted in each 32 output cycle frame to achieve more timing resolution on the average prescaler frequency as shown in Table 15-10. Reset clears PSSB4–PSSB0. Use the following formula to calculate the ESCI baud rate: Frequency of the SCI clock source Baud rate = 64 x BPD x BD x (PD + PDFA) where: Frequency of the SCI clock source = f or CGMXCLK (selected by Bus ESCIBDSRC in the CONFIG2 register) BPD = Baud rate register prescaler divisor BD = Baud rate divisor PD = Prescaler divisor PDFA = Prescaler divisor fine adjust MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 206 Freescale Semiconductor

I/O Registers Table 15-11 shows the ESCI baud rates that can be generated with a 4.9152-MHz bus frequency. Table 15-10. ESCI Prescaler Divisor Fine Adjust PSSB[4:3:2:1:0] Prescaler Divisor Fine Adjust (PDFA) 0 0 0 0 0 0/32 = 0 0 0 0 0 1 1/32 = 0.03125 0 0 0 1 0 2/32 = 0.0625 0 0 0 1 1 3/32 = 0.09375 0 0 1 0 0 4/32 = 0.125 0 0 1 0 1 5/32 = 0.15625 0 0 1 1 0 6/32 = 0.1875 0 0 1 1 1 7/32 = 0.21875 0 1 0 0 0 8/32 = 0.25 0 1 0 0 1 9/32 = 0.28125 0 1 0 1 0 10/32 = 0.3125 0 1 0 1 1 11/32 = 0.34375 0 1 1 0 0 12/32 = 0.375 0 1 1 0 1 13/32 = 0.40625 0 1 1 1 0 14/32 = 0.4375 0 1 1 1 1 15/32 = 0.46875 1 0 0 0 0 16/32 = 0.5 1 0 0 0 1 17/32 = 0.53125 1 0 0 1 0 18/32 = 0.5625 1 0 0 1 1 19/32 = 0.59375 1 0 1 0 0 20/32 = 0.625 1 0 1 0 1 21/32 = 0.65625 1 0 1 1 0 22/32 = 0.6875 1 0 1 1 1 23/32 = 0.71875 1 1 0 0 0 24/32 = 0.75 1 1 0 0 1 25/32 = 0.78125 1 1 0 1 0 26/32 = 0.8125 1 1 0 1 1 27/32 = 0.84375 1 1 1 0 0 28/32 = 0.875 1 1 1 0 1 29/32 = 0.90625 1 1 1 1 0 30/32 = 0.9375 1 1 1 1 1 31/32 = 0.96875 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 207

Enhanced Serial Communications Interface (ESCI) Module Table 15-11. ESCI Baud Rate Selection Examples Prescaler Baud Rate Baud Rate PS[2:1:0] PSSB[4:3:2:1:0] SCP[1:0] Divisor SCR[2:1:0] Divisor (f = 4.9152 MHz) (BPD) (BD) Bus 0 0 0 X X X X X 0 0 1 0 0 0 1 76,800 1 1 1 0 0 0 0 0 0 0 1 0 0 0 1 9600 1 1 1 0 0 0 0 1 0 0 1 0 0 0 1 9562.65 1 1 1 0 0 0 1 0 0 0 1 0 0 0 1 9525.58 1 1 1 1 1 1 1 1 0 0 1 0 0 0 1 8563.07 0 0 0 X X X X X 0 0 1 0 0 1 2 38,400 0 0 0 X X X X X 0 0 1 0 1 0 4 19,200 0 0 0 X X X X X 0 0 1 0 1 1 8 9600 0 0 0 X X X X X 0 0 1 1 0 0 16 4800 0 0 0 X X X X X 0 0 1 1 0 1 32 2400 0 0 0 X X X X X 0 0 1 1 1 0 64 1200 0 0 0 X X X X X 0 0 1 1 1 1 128 600 0 0 0 X X X X X 0 1 3 0 0 0 1 25,600 0 0 0 X X X X X 0 1 3 0 0 1 2 12,800 0 0 0 X X X X X 0 1 3 0 1 0 4 6400 0 0 0 X X X X X 0 1 3 0 1 1 8 3200 0 0 0 X X X X X 0 1 3 1 0 0 16 1600 0 0 0 X X X X X 0 1 3 1 0 1 32 800 0 0 0 X X X X X 0 1 3 1 1 0 64 400 0 0 0 X X X X X 0 1 3 1 1 1 128 200 0 0 0 X X X X X 1 0 4 0 0 0 1 19,200 0 0 0 X X X X X 1 0 4 0 0 1 2 9600 0 0 0 X X X X X 1 0 4 0 1 0 4 4800 0 0 0 X X X X X 1 0 4 0 1 1 8 2400 0 0 0 X X X X X 1 0 4 1 0 0 16 1200 0 0 0 X X X X X 1 0 4 1 0 1 32 600 0 0 0 X X X X X 1 0 4 1 1 0 64 300 0 0 0 X X X X X 1 0 4 1 1 1 128 150 0 0 0 X X X X X 1 1 13 0 0 0 1 5908 0 0 0 X X X X X 1 1 13 0 0 1 2 2954 0 0 0 X X X X X 1 1 13 0 1 0 4 1477 0 0 0 X X X X X 1 1 13 0 1 1 8 739 0 0 0 X X X X X 1 1 13 1 0 0 16 369 0 0 0 X X X X X 1 1 13 1 0 1 32 185 0 0 0 X X X X X 1 1 13 1 1 0 64 92 0 0 0 X X X X X 1 1 13 1 1 1 128 46 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 208 Freescale Semiconductor

ESCI Arbiter 15.9 ESCI Arbiter The ESCI module comprises an arbiter module designed to support software for communication tasks as bus arbitration, baud rate recovery and break time detection. The arbiter module consists of an 9-bit counter with 1-bit overflow and control logic. The CPU can control operation mode via the ESCI arbiter control register (SCIACTL). 15.9.1 ESCI Arbiter Control Register Address: $000A Bit 7 6 5 4 3 2 1 Bit 0 Read: ALOST AFIN ARUN AROVFL ARD8 AM1 AM0 ACLK Write: Reset: 0 0 0 0 0 0 0 0 =Unimplemented Figure 15-19. ESCI Arbiter Control Register (SCIACTL) AM1 and AM0 — Arbiter Mode Select Bits These read/write bits select the mode of the arbiter module as shown in Table 15-12. Reset clears AM1 and AM0. Table 15-12. ESCI Arbiter Selectable Modes AM[1:0] ESCI Arbiter Mode 0 0 Idle / counter reset 0 1 Bit time measurement 1 0 Bus arbitration 1 1 Reserved / do not use ALOST — Arbitration Lost Flag This read-only bit indicates loss of arbitration. Clear ALOST by writing a logic 0 to AM1. Reset clears ALOST. ACLK — Arbiter Counter Clock Select Bit This read/write bit selects the arbiter counter clock source. Reset clears ACLK. 1 = Arbiter counter is clocked with one quarter of the ESCI input clock generated by the ESCI prescaler 0 = Arbiter counter is clocked with the bus clock divided by four NOTE For ACLK = 1, the Arbiter input clock is driven from the ESCI prescaler. The prescaler can be clocked by either the bus clock or CGMXCLK depending on the state of the ESCIBDSRC bit in CONFIG2. AFIN— Arbiter Bit Time Measurement Finish Flag This read-only bit indicates bit time measurement has finished. Clear AFIN by writing any value to SCIACTL. Reset clears AFIN. 1 = Bit time measurement has finished 0 = Bit time measurement not yet finished MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 209

Enhanced Serial Communications Interface (ESCI) Module ARUN— Arbiter Counter Running Flag This read-only bit indicates the arbiter counter is running. Reset clears ARUN. 1 = Arbiter counter running 0 = Arbiter counter stopped AROVFL— Arbiter Counter Overflow Bit This read-only bit indicates an arbiter counter overflow. Clear AROVFL by writing any value to SCIACTL. Writing logic 0s to AM1 and AM0 resets the counter keeps it in this idle state. Reset clears AROVFL. 1 = Arbiter counter overflow has occurred 0 = No arbiter counter overflow has occurred ARD8— Arbiter Counter MSB This read-only bit is the MSB of the 9-bit arbiter counter. Clear ARD8 by writing any value to SCIACTL. Reset clears ARD8. 15.9.2 ESCI Arbiter Data Register Address: $000B Bit 7 6 5 4 3 2 1 Bit 0 Read: ARD7 ARD6 ARD5 ARD4 ARD3 ARD2 ARD1 ARD0 Write: Reset: 0 0 0 0 0 0 0 0 =Unimplemented Figure 15-20. ESCI Arbiter Data Register (SCIADAT) ARD7–ARD0 — Arbiter Least Significant Counter Bits These read-only bits are the eight LSBs of the 9-bit arbiter counter. Clear ARD7–ARD0 by writing any value to SCIACTL. Writing logic 0s to AM1 and AM0 permanently resets the counter and keeps it in this idle state. Reset clears ARD7–ARD0. 15.9.3 Bit Time Measurement Two bit time measurement modes, described here, are available according to the state of ACLK. 1. ACLK = 0 — The counter is clocked with the bus clock divided by four. The counter is started when a falling edge on the RxD pin is detected. The counter will be stopped on the next falling edge. ARUN is set while the counter is running, AFIN is set on the second falling edge on RxD (for instance, the counter is stopped). This mode is used to recover the received baud rate. See Figure 15-21. 2. ACLK = 1 — The counter is clocked with one quarter of the ESCI input clock generated by the ESCI prescaler. The counter is started when a logic 0 is detected on RxD (see Figure 15-22). A logic 0 on RxD on enabling the bit time measurement with ACLK = 1 leads to immediate start of the counter (see Figure 15-23). The counter will be stopped on the next rising edge of RxD. This mode is used to measure the length of a received break. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 210 Freescale Semiconductor

ESCI Arbiter MEASURED TIME RXD U WRITES SCIACTLWITH $20 COUNTER STARTS,ARUN = 1 COUNTER STOPS,AFIN = 1 PU READS RESULTOUT OF SCIADAT P C C Figure 15-21. Bit Time Measurement with ACLK = 0 MEASURED TIME RXD WRITES SCIACTL WITH $30OUNTER STARTS, ARUN = 1 COUNTER STOPS, AFIN = 1 CPU READS RESULT OUTOF SCIADAT U C P C Figure 15-22. Bit Time Measurement with ACLK = 1, Scenario A MEASURED TIME RXD U WRITES SCIACTLWITH $30 COUNTER STARTS,ARUN = 1 COUNTER STOPS,AFIN = 1 PU READS RESULTOUT OF SCIADAT P C C Figure 15-23. Bit Time Measurement with ACLK = 1, Scenario B MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 211

Enhanced Serial Communications Interface (ESCI) Module 15.9.4 Arbitration Mode If AM[1:0] is set to 10, the arbiter module operates in arbitration mode. On every rising edge of SCI_TxD (output of the ESCI module, internal chip signal), the counter is started. When the counter reaches $38 (ACLK = 0) or $08 (ACLK = 1), RxD is statically sensed. If in this case, RxD is sensed low (for example, another bus is driving the bus dominant) ALOST is set. As long as ALOST is set, the TxD pin is forced to 1, resulting in a seized transmission. If SCI_TxD is sensed logic 0 without having sensed a logic 0 before on RxD, the counter will be reset, arbitration operation will be restarted after the next rising edge of SCI_TxD. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 212 Freescale Semiconductor

Chapter 16 System Integration Module (SIM) 16.1 Introduction This section describes the system integration module (SIM). Together with the central processor unit (CPU), the SIM controls all microcontroller unit (MCU) activities. A block diagram of the SIM is shown in Figure 16-1. Table 16-1 is a summary of the SIM input/output (I/O) registers. The SIM is a system state controller that coordinates CPU and exception timing. MODULE STOP MODULE WAIT STOP/WAIT CPU STOP (FROM CPU) CONTROL CPU WAIT (FROM CPU) SIMOSCEN (TO CGM) SIM CGMXCLK (FROM CGM) COUNTER CGMOUT (FROM CGM) ÷ 2 VDD CCOLNOTCRKOL CLOCK GENERATORS INTERNAL CLOCKS INTERNAL PULLUP DEVICE FORCED MONITOR MODE ENTRY RESET POR CONTROL LVI (FROM LVI MODULE) PIN LOGIC MASTER ILLEGAL OPCODE (FROM CPU) RESET PIN CONTROL RESET ILLEGAL ADDRESS (FROM ADDRESS CONTROL MAP DECODERS) SIM RESET STATUS REGISTER COP (FROM COP MODULE) RESET INTERRUPT SOURCES INTERRUPT CONTROL AND PRIORITY DECODE CPU INTERFACE Figure 16-1. SIM Block Diagram MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 213

System Integration Module (SIM) The SIM is responsible for: (cid:129) Bus clock generation and control for CPU and peripherals: – Stop/wait/reset/break entry and recovery – Internal clock control (cid:129) Master reset control, including power-on reset (POR) and computer operating properly (COP) timeout (cid:129) Interrupt control: – Acknowledge timing – Arbitration control timing – Vector address generation (cid:129) CPU enable/disable timing (cid:129) Modular architecture expandable to 128 interrupt sources Table 16-1 shows the internal signal names used in this section. Table 16-1. Signal Name Conventions Signal Name Description CGMXCLK Buffered version of OSC1 from clock generator module (CGM) CGMVCLK PLL output CGMOUT PLL-based or OSC1-based clock output from CGM module (Bus clock=CGMOUT divided by two) IAB Internal address bus IDB Internal data bus PORRST Signal from the power-on reset module to the SIM IRST Internal reset signal R/W Read/write signal Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 SIM Break Status Read: SBSW R R R R R R R $FE00 Register (SBSR) Write: Note(1) See page 228. Reset: 0 0 0 0 0 0 0 0 1. Writing a logic 0 clears SBSW. SIM Reset Status Read: POR PIN COP ILOP ILAD MODRST LVI 0 $FE01 Register (SRSR) Write: See page 228. POR: 1 0 0 0 0 0 0 0 SIM Break Flag Control Read: BCFE R R R R R R R $FE03 Register (SBFCR) Write: See page 229. Reset: 0 Interrupt Status Read: IF6 IF5 IF4 IF3 IF2 IF1 0 0 $FE04 Register1 (INT1) Write: R R R R R R R R See page 224. Reset: 0 0 0 0 0 0 0 0 Interrupt Status Read: IF14 IF13 IF12 IF11 IF10 IF9 IF8 IF7 $FE05 Register2 (INT2) Write: R R R R R R R R See page 224. Reset: 0 0 0 0 0 0 0 0 Interrupt Status Read: 0 0 IF20 IF19 IF18 IF17 IF16 IF15 $FE06 Register3 (INT3) Write: R R R R R R R R See page 224. Reset: 0 0 0 0 0 0 0 0 = Unimplemented R = Reserved Figure 16-2. SIM I/O Register Summary MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 214 Freescale Semiconductor

SIM Bus Clock Control and Generation 16.2 SIM Bus Clock Control and Generation The bus clock generator provides system clock signals for the CPU and peripherals on the MCU. The system clocks are generated from an incoming clock, CGMOUT, as shown in Figure 16-3. This clock originates from either an external oscillator or from the on-chip PLL. 16.2.1 Bus Timing In user mode, the internal bus frequency is either the crystal oscillator output (CGMXCLK) divided by four or the PLL output (CGMVCLK) divided by four. 16.2.2 Clock Startup from POR or LVI Reset When the power-on reset module or the low-voltage inhibit module generates a reset, the clocks to the CPU and peripherals are inactive and held in an inactive phase until after the 4096 CGMXCLK cycle POR timeout has completed. The RST pin is driven low by the SIM during this entire period. The IBUS clocks start upon completion of the timeout. OSC2 OSCILLATOR (OSC) CGMXCLK TO TBM,TIM1,TIM2, ADC, MSCAN OSC1 SIM SIMOSCEN OSCENINSTOP FROM CONFIG CGMRCLK SIM COUNTER IT12 TO REST OF CHIP CGMOUT ÷ 2 BUS CLOCK IT23 GENERATORS TO REST PHASE-LOCKED LOOP (PLL) OF CHIP TO MSCAN Figure 16-3. System Clock Signals 16.2.3 Clocks in Stop Mode and Wait Mode Upon exit from stop mode by an interrupt or reset, the SIM allows CGMXCLK to clock the SIM counter. The CPU and peripheral clocks do not become active until after the stop delay timeout. This timeout is selectable as 4096 or 32 CGMXCLK cycles. See 16.6.2 Stop Mode. In wait mode, the CPU clocks are inactive. The SIM also produces two sets of clocks for other modules. Refer to the wait mode subsection of each module to see if the module is active or inactive in wait mode. Some modules can be programmed to be active in wait mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 215

System Integration Module (SIM) 16.3 Reset and System Initialization The MCU has these reset sources: (cid:129) Power-on reset module (POR) (cid:129) External reset pin (RST) (cid:129) Computer operating properly module (COP) (cid:129) Low-voltage inhibit module (LVI) (cid:129) Illegal opcode (cid:129) Illegal address (cid:129) Forced monitor mode entry reset (MODRST) All of these resets produce the vector $FFFE:$FFFF ($FEFE:$FEFF in monitor mode) and assert the internal reset signal (IRST). IRST causes all registers to be returned to their default values and all modules to be returned to their reset states. An internal reset clears the SIM counter (see 16.4 SIM Counter), but an external reset does not. Each of the resets sets a corresponding bit in the SIM reset status register (SRSR). See 16.7 SIM Registers. 16.3.1 External Pin Reset The RST pin circuit includes an internal pullup device. Pulling the asynchronous RST pin low halts all processing. The PIN bit of the SIM reset status register (SRSR) is set as long as RST is held low for a minimum of 67 CGMXCLK cycles, assuming that neither the POR nor the LVI was the source of the reset. See Table 16-2 for details. Figure 16-4 shows the relative timing. Table 16-2. PIN Bit Set Timing Reset Type Number of Cycles Required to Set PIN POR/LVI 4163 (4096 + 64 + 3) All others 67 (64 + 3) CGMOUT RST IAB PC VECT H VECT L Figure 16-4. External Reset Timing MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 216 Freescale Semiconductor

Reset and System Initialization 16.3.2 Active Resets from Internal Sources All internal reset sources actively pull the RST pin low for 32 CGMXCLK cycles to allow resetting of external peripherals. The internal reset continues to be asserted for an additional 32 cycles at which point the reset vector will be fetched. See Figure 16-5. An internal reset can be caused by an illegal address, illegal opcode, COP timeout, LVI, or POR. See Figure 16-6. NOTE For LVI or POR resets, the SIM cycles through 4096 + 32 CGMXCLK cycles during which the SIM forces the RST pin low. The internal reset signal then follows the sequence from the falling edge of RST shown in Figure 16-5. RST RST PULLED LOW BY MCU 32 CYCLES 32 CYCLES CGMXCLK IAB VECTOR HIGH Figure 16-5. Internal Reset Timing ILLEGAL ADDRESS RST ILLEGAL OPCODE RST COPRST INTERNAL RESET LVI POR MODRST Figure 16-6. Sources of Internal Reset The COP reset is asynchronous to the bus clock. The active reset feature allows the part to issue a reset to peripherals and other chips within a system built around the MCU. 16.3.2.1 Power-On Reset When power is first applied to the MCU, the power-on reset module (POR) generates a pulse to indicate that power-on has occurred. The external reset pin (RST) is held low while the SIM counter counts out 4096 + 32 CGMXCLK cycles. Thirty-two CGMXCLK cycles later, the CPU and memories are released from reset to allow the reset vector sequence to occur. At power-on, these events occur: (cid:129) A POR pulse is generated. (cid:129) The internal reset signal is asserted. (cid:129) The SIM enables CGMOUT. (cid:129) Internal clocks to the CPU and modules are held inactive for 4096 CGMXCLK cycles to allow stabilization of the oscillator. (cid:129) The RST pin is driven low during the oscillator stabilization time. (cid:129) The POR bit of the SIM reset status register (SRSR) is set and all other bits in the register are cleared. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 217

System Integration Module (SIM) 16.3.2.2 Computer Operating Properly (COP) Reset An input to the SIM is reserved for the COP reset signal. The overflow of the COP counter causes an internal reset and sets the COP bit in the SIM reset status register (SRSR). The SIM actively pulls down the RST pin for all internal reset sources. The COP module is disabled if the RST pin or the IRQ pin is held at V while the MCU is in monitor TST mode. The COP module can be disabled only through combinational logic conditioned with the high voltage signal on the RST or the IRQ pin. This prevents the COP from becoming disabled as a result of external noise. During a break state, V on the RST pin disables the COP module. TST OSC1 PORRST 4096 32 CYCLES CYCLES CGMXCLK CGMOUT RST IAB $FFFE $FFFF Figure 16-7. POR Recovery 16.3.2.3 Illegal Opcode Reset The SIM decodes signals from the CPU to detect illegal instructions. An illegal instruction sets the ILOP bit in the SIM reset status register (SRSR) and causes a reset. If the stop enable bit, STOP, in the mask option register is logic 0, the SIM treats the STOP instruction as an illegal opcode and causes an illegal opcode reset. The SIM actively pulls down the RST pin for all internal reset sources. 16.3.2.4 Illegal Address Reset An opcode fetch from an unmapped address generates an illegal address reset. The SIM verifies that the CPU is fetching an opcode prior to asserting the ILAD bit in the SIM reset status register (SRSR) and resetting the MCU. A data fetch from an unmapped address does not generate a reset. The SIM actively pulls down the RST pin for all internal reset sources. 16.3.2.5 Low-Voltage Inhibit (LVI) Reset The low-voltage inhibit module (LVI) asserts its output to the SIM when the V voltage falls to the DD LVI voltage. The LVI bit in the SIM reset status register (SRSR) is set, and the external reset pin TRIPF (RST) is held low while the SIM counter counts out 4096 + 32 CGMXCLK cycles. Thirty-two CGMXCLK cycles later, the CPU is released from reset to allow the reset vector sequence to occur. The SIM actively pulls down the RST pin for all internal reset sources. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 218 Freescale Semiconductor

SIM Counter 16.3.2.6 Monitor Mode Entry Module Reset (MODRST) The monitor mode entry module reset (MODRST) asserts its output to the SIM when monitor mode is entered in the condition where the reset vectors are erased ($FF) (see 20.3.1.1 Normal Monitor Mode). When MODRST gets asserted, an internal reset occurs. The SIM actively pulls down the RST pin for all internal reset sources. 16.4 SIM Counter The SIM counter is used by the power-on reset module (POR) and in stop mode recovery to allow the oscillator time to stabilize before enabling the internal bus (IBUS) clocks. The SIM counter is 13 bits long. 16.4.1 SIM Counter During Power-On Reset The power-on reset module (POR) detects power applied to the MCU. At power-on, the POR circuit asserts the signal PORRST. Once the SIM is initialized, it enables the clock generation module (CGM) to drive the bus clock state machine. 16.4.2 SIM Counter During Stop Mode Recovery The SIM counter also is used for stop mode recovery. The STOP instruction clears the SIM counter. After an interrupt, break, or reset, the SIM senses the state of the short stop recovery bit, SSREC, in the mask option register. If the SSREC bit is a logic 1, then the stop recovery is reduced from the normal delay of 4096 CGMXCLK cycles down to 32 CGMXCLK cycles. This is ideal for applications using canned oscillators that do not require long startup times from stop mode. External crystal applications should use the full stop recovery time, that is, with SSREC cleared. 16.4.3 SIM Counter and Reset States External reset has no effect on the SIM counter. See 16.6.2 Stop Mode for details. The SIM counter is free-running after all reset states. See 16.3.2 Active Resets from Internal Sources for counter control and internal reset recovery sequences. 16.5 Exception Control Normal, sequential program execution can be changed in three different ways: (cid:129) Interrupts: – Maskable hardware CPU interrupts – Non-maskable software interrupt instruction (SWI) (cid:129) Reset (cid:129) Break interrupts 16.5.1 Interrupts At the beginning of an interrupt, the CPU saves the CPU register contents on the stack and sets the interrupt mask (I bit) to prevent additional interrupts. At the end of an interrupt, the RTI instruction recovers the CPU register contents from the stack so that normal processing can resume. Figure 16-8 shows interrupt entry timing. Figure 16-9 shows interrupt recovery timing. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 219

System Integration Module (SIM) Interrupts are latched, and arbitration is performed in the SIM at the start of interrupt processing. The arbitration result is a constant that the CPU uses to determine which vector to fetch. Once an interrupt is latched by the SIM, no other interrupt can take precedence, regardless of priority, until the latched interrupt is serviced (or the I bit is cleared). See Figure 16-10. MODULE INTERRUPT I BIT IAB DUMMY SP SP – 1 SP – 2 SP – 3 SP – 4 VECT H VECT L START ADDR IDB DUMMY PC – 1[7:0] PC – 1[15:8] X A CCR V DATA H V DATA L OPCODE R/W Figure 16-8. Interrupt Entry Timing MODULE INTERRUPT I BIT IAB SP – 4 SP – 3 SP – 2 SP – 1 SP PC PC + 1 IDB CCR A X PC – 1 [7:0] PC – 1 [15:8] OPCODE OPERAND R/W Figure 16-9. Interrupt Recovery Timing MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 220 Freescale Semiconductor

Exception Control FROM RESET I BBIRT ESAEKT? YES INTERRUPT? NO YES I BIT SET? NO IRQ YES INTERRUPT? NO AS MANY INTERRUPTS AS EXIST ON CHIP STACK CPU REGISTERS SET I BIT LOAD PC WITH INTERRUPT VECTOR FETCH NEXT INSTRUCTION SWI YES INSTRUCTION? NO RTI YES INSTRUCTION? UNSTACK CPU REGISTERS NO EXECUTE INSTRUCTION Figure 16-10. Interrupt Processing MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 221

System Integration Module (SIM) 16.5.1.1 Hardware Interrupts A hardware interrupt does not stop the current instruction. Processing of a hardware interrupt begins after completion of the current instruction. When the current instruction is complete, the SIM checks all pending hardware interrupts. If interrupts are not masked (I bit clear in the condition code register) and if the corresponding interrupt enable bit is set, the SIM proceeds with interrupt processing; otherwise, the next instruction is fetched and executed. If more than one interrupt is pending at the end of an instruction execution, the highest priority interrupt is serviced first. Figure 16-11 demonstrates what happens when two interrupts are pending. If an interrupt is pending upon exit from the original interrupt service routine, the pending interrupt is serviced before the LDA instruction is executed. The LDA opcode is prefetched by both the INT1 and INT2 RTI instructions. However, in the case of the INT1 RTI prefetch, this is a redundant operation. NOTE To maintain compatibility with the M6805 Family, the H register is not pushed on the stack during interrupt entry. If the interrupt service routine modifies the H register or uses the indexed addressing mode, software should save the H register and then restore it prior to exiting the routine. CLI BACKGROUND LDA #$FF ROUTINE INT1 PSHH INT1 INTERRUPT SERVICE ROUTINE PULH RTI INT2 PSHH INT2 INTERRUPT SERVICE ROUTINE PULH RTI Figure 16-11. Interrupt Recognition Example MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 222 Freescale Semiconductor

Exception Control 16.5.1.2 SWI Instruction The SWI instruction is a non-maskable instruction that causes an interrupt regardless of the state of the interrupt mask (I bit) in the condition code register. NOTE A software interrupt pushes PC onto the stack. A software interrupt does not push PC – 1, as a hardware interrupt does. 16.5.1.3 Interrupt Status Registers The flags in the interrupt status registers identify maskable interrupt sources. Table 16-3 summarizes the interrupt sources and the interrupt status register flags that they set. The interrupt status registers can be useful for debugging. Table 16-3. Interrupt Sources Priority Interrupt Source Interrupt Status Register Flag Highest Reset — SWI instruction — IRQ pin I1 CGM clock monitor I2 TIM1 channel 0 I3 TIM1 channel 1 I4 TIM1 overflow I5 TIM2 channel 0 I6 TIM2 channel 1 I7 TIM2 overflow I8 SPI receiver full I9 SPI transmitter empty I10 SCI receive error I11 SCI receive I12 SCI transmit I13 Keyboard I14 ADC conversion complete I15 Timebase module I16 MSCAN08 wakeup I17 MSCAN08 error I18 MSCAN08 receive I19 Lowest MSCAN08 transmit I20 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 223

System Integration Module (SIM) Interrupt Status Register 1 Address: $FE04 Bit 7 6 5 4 3 2 1 Bit 0 Read: I6 I5 I4 I3 I2 I1 0 0 Write: R R R R R R R R Reset: 0 0 0 0 0 0 0 0 R = Reserved Figure 16-12. Interrupt Status Register 1 (INT1) I6–I1 — Interrupt Flags 1–6 These flags indicate the presence of interrupt requests from the sources shown in Table 16-3. 1 = Interrupt request present 0 = No interrupt request present Bit 0 and Bit 1 — Always read 0 Interrupt Status Register 2 Address: $FE05 Bit 7 6 5 4 3 2 1 Bit 0 Read: I14 I13 I12 I11 I10 I9 I8 I7 Write: R R R R R R R R Reset: 0 0 0 0 0 0 0 0 R = Reserved Figure 16-13. Interrupt Status Register 2 (INT2) I14–I7 — Interrupt Flags 14–7 These flags indicate the presence of interrupt requests from the sources shown in Table 16-3. 1 = Interrupt request present 0 = No interrupt request present Interrupt Status Register 3 Address: $FE06 Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 I20 I19 I18 I17 I16 I15 Write: R R R R R R R R Reset: 0 0 0 0 0 0 0 0 R = Reserved Figure 16-14. Interrupt Status Register 3 (INT3) Bits 7–6 — Always read 0 I20–I15 — Interrupt Flags 20–15 These flags indicate the presence of an interrupt request from the source shown in Table 16-3. 1 = Interrupt request present 0 = No interrupt request present MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 224 Freescale Semiconductor

Low-Power Modes 16.5.2 Reset All reset sources always have equal and highest priority and cannot be arbitrated. 16.5.3 Break Interrupts The break module can stop normal program flow at a software-programmable break point by asserting its break interrupt output (see Chapter 19 Timer Interface Module (TIM)). The SIM puts the CPU into the break state by forcing it to the SWI vector location. Refer to the break interrupt subsection of each module to see how each module is affected by the break state. 16.5.4 Status Flag Protection in Break Mode The SIM controls whether status flags contained in other modules can be cleared during break mode. The user can select whether flags are protected from being cleared by properly initializing the break clear flag enable bit (BCFE) in the SIM break flag control register (SBFCR). Protecting flags in break mode ensures that set flags will not be cleared while in break mode. This protection allows registers to be freely read and written during break mode without losing status flag information. Setting the BCFE bit enables the clearing mechanisms. Once cleared in break mode, a flag remains cleared even when break mode is exited. Status flags with a 2-step clearing mechanism — for example, a read of one register followed by the read or write of another — are protected, even when the first step is accomplished prior to entering break mode. Upon leaving break mode, execution of the second step will clear the flag as normal. 16.6 Low-Power Modes Executing the WAIT or STOP instruction puts the MCU in a low power- consumption mode for standby situations. The SIM holds the CPU in a non-clocked state. The operation of each of these modes is described in the following subsections. Both STOP and WAIT clear the interrupt mask (I) in the condition code register, allowing interrupts to occur. 16.6.1 Wait Mode In wait mode, the CPU clocks are inactive while the peripheral clocks continue to run. Figure 16-15 shows the timing for wait mode entry. A module that is active during wait mode can wakeup the CPU with an interrupt if the interrupt is enabled. Stacking for the interrupt begins one cycle after the WAIT instruction during which the interrupt occurred. In wait mode, the CPU clocks are inactive. Refer to the wait mode subsection of each module to see if the module is active or inactive in wait mode. Some modules can be programmed to be active in wait mode. Wait mode also can be exited by a reset (or break in emulation mode). A break interrupt during wait mode sets the SIM break stop/wait bit, SBSW, in the SIM break status register (SBSR). If the COP disable bit, COPD, in the mask option register is logic 0, then the computer operating properly module (COP) is enabled and remains active in wait mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 225

System Integration Module (SIM) IAB WAIT ADDR WAIT ADDR + 1 SAME SAME IDB PREVIOUS DATA NEXT OPCODE SAME SAME R/W Note: Previous data can be operand data or the WAIT opcode, depending on the last instruction. Figure 16-15. Wait Mode Entry Timing Figure 16-16 and Figure 16-17 show the timing for WAIT recovery. IAB $6E0B $6E0C $00FF $00FE $00FD $00FC IDB $A6 $A6 $A6 $01 $0B $6E EXITSTOPWAIT Note: EXITSTOPWAIT = RST pin or CPU interrupt Figure 16-16. Wait Recovery from Interrupt 32 32 CYCLES CYCLES IAB $6E0B RST VCT H RST VCT L IDB $A6 $A6 $A6 RST CGMXCLK Figure 16-17. Wait Recovery from Internal Reset 16.6.2 Stop Mode In stop mode, the SIM counter is reset and the system clocks are disabled. An interrupt request from a module can cause an exit from stop mode. Stacking for interrupts begins after the selected stop recovery time has elapsed. Reset causes an exit from stop mode. The SIM disables the clock generator module outputs (CGMOUT and CGMXCLK) in stop mode, stopping the CPU and peripherals. Stop recovery time is selectable using the SSREC bit in the mask option register (MOR). If SSREC is set, stop recovery is reduced from the normal delay of 4096 CGMXCLK cycles down to 32. This is ideal for applications using canned oscillators that do not require long startup times from stop mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 226 Freescale Semiconductor

SIM Registers NOTE External crystal applications should use the full stop recovery time by clearing the SSREC bit. The SIM counter is held in reset from the execution of the STOP instruction until the beginning of stop recovery. It is then used to time the recovery period. Figure 16-18 shows stop mode entry timing. Figure 16-19 shows stop mode recovery time from interrupt. NOTE To minimize stop current, all pins configured as inputs should be driven to a logic 1 or logic 0. CPUSTOP IAB STOP ADDR STOP ADDR + 1 SAME SAME IDB PREVIOUS DATA NEXT OPCODE SAME SAME R/W Note: Previous data can be operand data or the STOP opcode, depending on the last instruction. Figure 16-18. Stop Mode Entry Timing STOP RECOVERY PERIOD CGMXCLK INT/BREAK IAB STOP +1 STOP + 2 STOP + 2 SP SP – 1 SP – 2 SP – 3 Figure 16-19. Stop Mode Recovery from Interrupt 16.7 SIM Registers The SIM has three memory-mapped registers. Table 16-4 shows the mapping of these registers. Table 16-4. SIM Registers Address Register Access Mode $FE00 SBSR User $FE01 SRSR User $FE03 SBFCR User MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 227

System Integration Module (SIM) 16.7.1 Break Status Register The break status register (BSR) contains a flag to indicate that a break caused an exit from wait mode. This register is only used in emulation mode. Address: $FE00 Bit 7 6 5 4 3 2 1 Bit 0 Read: SBSW R R R R R R R Write: Note(1) Reset: 0 0 0 0 0 0 0 0 R = Reserved 1. Writing a logic 0 clears SBSW. Figure 16-20. Break Status Register (BSR) SBSW — SIM Break Stop/Wait SBSW can be read within the break state SWI routine. The user can modify the return address on the stack by subtracting one from it. 1 = Wait mode was exited by break interrupt. 0 = Wait mode was not exited by break interrupt. 16.7.2 SIM Reset Status Register This register contains six flags that show the source of the last reset provided all previous reset status bits have been cleared. Clear the SIM reset status register by reading it. A power-on reset sets the POR bit and clears all other bits in the register. Address: $FE01 Bit 7 6 5 4 3 2 1 Bit 0 Read: POR PIN COP ILOP ILAD MODRST LVI 0 Write: Reset: 1 0 0 0 0 0 0 0 = Unimplemented Figure 16-21. SIM Reset Status Register (SRSR) POR — Power-On Reset Bit 1 = Last reset caused by POR circuit 0 = Read of SRSR PIN — External Reset Bit 1 = Last reset caused by external reset pin (RST) 0 = POR or read of SRSR COP — Computer Operating Properly Reset Bit 1 = Last reset caused by COP counter 0 = POR or read of SRSR ILOP — Illegal Opcode Reset Bit 1 = Last reset caused by an illegal opcode 0 = POR or read of SRSR MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 228 Freescale Semiconductor

SIM Registers ILAD — Illegal Address Reset Bit (opcode fetches only) 1 = Last reset caused by an opcode fetch from an illegal address 0 = POR or read of SRSR MODRST — Monitor Mode Entry Module Reset Bit 1 = Last reset caused by monitor mode entry when vector locations $FFFE and $FFFF are $FF after POR while IRQ = V DD 0 = POR or read of SRSR LVI — Low-Voltage Inhibit Reset Bit 1 = Last reset caused by the LVI circuit 0 = POR or read of SRSR 16.7.3 Break Flag Control Register The break flag control register (BFCR) contains a bit that enables software to clear status bits while the MCU is in a break state. Address: $FE03 Bit 7 6 5 4 3 2 1 Bit 0 Read: BCFE R R R R R R R Write: Reset: 0 R = Reserved Figure 16-22. Break Flag Control Register (BFCR) BCFE — Break Clear Flag Enable Bit This read/write bit enables software to clear status bits by accessing status registers while the MCU is in a break state. To clear status bits during the break state, the BCFE bit must be set. 1 = Status bits clearable during break 0 = Status bits not clearable during break MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 229

System Integration Module (SIM) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 230 Freescale Semiconductor

Chapter 17 Serial Peripheral Interface (SPI) Module 17.1 Introduction This section describes the serial peripheral interface (SPI) module, which allows full-duplex, synchronous, serial communications with peripheral devices. 17.2 Features Features of the SPI module include: (cid:129) Full-duplex operation (cid:129) Master and slave modes (cid:129) Double-buffered operation with separate transmit and receive registers (cid:129) Four master mode frequencies (maximum = bus frequency ÷ 2) (cid:129) Maximum slave mode frequency = bus frequency (cid:129) Serial clock with programmable polarity and phase (cid:129) Two separately enabled interrupts: – SPRF (SPI receiver full) – SPTE (SPI transmitter empty) (cid:129) Mode fault error flag with CPU interrupt capability (cid:129) Overflow error flag with CPU interrupt capability (cid:129) Programmable wired-OR mode (cid:129) I2C (inter-integrated circuit) compatibility (cid:129) I/O (input/output) port bit(s) software configurable with pullup device(s) if configured as input port bit(s) 17.3 Pin Name Conventions The text that follows describes the SPI. The SPI I/O pin names are SS (slave select), SPSCK (SPI serial clock), CGND (clock ground), MOSI (master out slave in), and MISO (master in/slave out). The SPI shares four I/O pins with four parallel I/O ports. The full names of the SPI I/O pins are shown in Table 17-1. The generic pin names appear in the text that follows. Table 17-1. Pin Name Conventions SPI Generic MISO MOSI SS SPSCK CGND Pin Names: Full SPI Pin Names: SPI PTD1/MISO PTD2/MOSI PTD0/SS PTD3/SPSCK VSS MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 231

Serial Peripheral Interface (SPI) Module INTERNAL BUS M68HC08 CPU REGCISPTUERS ARITUHNMIET T(AICL/ULO)GIC PROGRAMMMOADBULLEE TIMEBASE DDRA PORTA PPTTAA70//KKBBDD70–(1) PTB7/AD7 SINGLE BREAKPOINT CONTROL AND STATUS REGISTERS — 64 BYTES PTB6/AD6 BREAK MODULE PTB5/AD5 USER FLASH — 15,872 BYTES LOWD-UVAOLL TVAOGLETA INGHEIBIT DDRB PORTB PPTTBB43//AADD43 MODULE PTB2/AD2 USER RAM — 1024 BYTES PTB1/AD1 8-BIT KEYBOARD PTB0/AD0 MONITOR ROM — 350 BYTES INTERRUPT MODULE PTC6(1) PTC5(1) FLASH PROGRAMMING ROUTINES ROM — 406 BYTES 2-CHANNEL TIMER USER FLASH VECTOR SPACE — 44 BYTES INTERFACE MODULE 1 DDRC PORTC PPPTTTCCC432(((111))),,, (((222))) 2-CHANNEL TIMER INTERFACE MODULE 2 PTC1/CANRX(1), (2) CLOCK GENERATOR MODULE PTC0/CAN (1), (2) TX OSC1 1–8 MHz OSCILLATOR ENHANCED SERIAL OSC2 COMUNICATIONS PTD7/T2CH1(1) PHASE LOCKED LOOP INTERFACE MODULE PTD6/T2CH0(1) CGMXFC PTD5/T1CH1(1) RST(3) SYSTEM INTEGRATION COPMRPOUPTEERRL YO MPEORDAUTLIENG DDRD PORTD PPPTTTDDD243///MTS1POCSSHCI(0K1()1(1)) MODULE SERIAL PERIPHERAL PTD1/MISO(1) INTERFACE MODULE PTD0/SS(1) IRQ(3) SINGLE EXTERNAL INTERRUPT MODULE PTE5–PTE2 VVDDAD//VVREFH 10-CBOITN AVNEARLTOEGR- TMOO-DDUIGLIETAL MONITOR MODULE DDRE PORTE PPTTEE10//RTxxDD DDAD REFL MEMORY MAP MODULE POWER-ON RESET MODULE SECURITY CONFIGURATION MODULE VDD REGISTER 1–2 VSS POWER MODULE V DDA V MONITOR MODE ENTRY SSA MSCAN08 MODULE MODULE 1. Ports are software configurable with pullup device if input port. 2. Higher current drive port pins 3. Pin contains integrated pullup device Figure 17-1. Block Diagram Highlighting SPI Block and Pins MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 232 Freescale Semiconductor

Functional Description 17.4 Functional Description Figure 17-2 summarizes the SPI I/O registers and Figure 17-3 shows the structure of the SPI module. The SPI module allows full-duplex, synchronous, serial communication between the MCU and peripheral devices, including other MCUs. Software can poll the SPI status flags or SPI operation can be interrupt driven. If a port bit is configured for input, then an internal pullup device may be enabled for that port bit. See 13.5.3 Port C Input Pullup Enable Register. The following paragraphs describe the operation of the SPI module. Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: SPI Control Register SPRIE R SPMSTR CPOL CPHA SPWOM SPE SPTIE $0010 (SPCR) Write: See page 247. Reset: 0 0 1 0 1 0 0 0 Read: SPRF OVRF MODF SPTE SPI Status and Control ERRIE MODFEN SPR1 SPR0 $0011 Register (SPSCR) Write: See page 249. Reset: 0 0 0 0 1 0 0 0 Read: R7 R6 R5 R4 R3 R2 R1 R0 SPI Data Register $0012 (SPDR) Write: T7 T6 T5 T4 T3 T2 T1 T0 See page 250. Reset: Unaffected by reset R = Reserved = Unimplemented Figure 17-2. SPI I/O Register Summary 17.4.1 Master Mode The SPI operates in master mode when the SPI master bit, SPMSTR, is set. NOTE Configure the SPI modules as master or slave before enabling them. Enable the master SPI before enabling the slave SPI. Disable the slave SPI before disabling the master SPI. See 17.13.1 SPI Control Register. Only a master SPI module can initiate transmissions. Software begins the transmission from a master SPI module by writing to the transmit data register. If the shift register is empty, the byte immediately transfers to the shift register, setting the SPI transmitter empty bit, SPTE. The byte begins shifting out on the MOSI pin under the control of the serial clock. See Figure 17-4. The SPR1 and SPR0 bits control the baud rate generator and determine the speed of the shift register. (See 17.13.2 SPI Status and Control Register.) Through the SPSCK pin, the baud rate generator of the master also controls the shift register of the slave peripheral. As the byte shifts out on the MOSI pin of the master, another byte shifts in from the slave on the master’s MISO pin. The transmission ends when the receiver full bit, SPRF, becomes set. At the same time that SPRF becomes set, the byte from the slave transfers to the receive data register. In normal operation, SPRF signals the end of a transmission. Software clears SPRF by reading the SPI status and control register with SPRF set and then reading the SPI data register. Writing to the SPI data register clears the SPTE bit. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 233

Serial Peripheral Interface (SPI) Module INTERNAL BUS TRANSMIT DATA REGISTER CGMOUT ÷ 2 SHIFT REGISTER FROM SIM 7 6 5 4 3 2 1 0 MISO ÷ 2 MOSI CLOCK ÷ 8 RECEIVE DATA REGISTER DIVIDER ÷ 32 PIN CONTROL ÷ 128 LOGIC CLOCK SPSCK SPMSTR SPE SELECT CLOCK M LOGIC S SS SPR1 SPR0 SPMSTR CPHA CPOL RESERVED MODFEN SPWOM TRANSMITTER CPU INTERRUPT REQUEST ERRIE SPI CONTROL SPTIE RESERVED SPRIE RECEIVER/ERROR CPU INTERRUPT REQUEST SPE SPRF SPTE OVRF MODF Figure 17-3. SPI Module Block Diagram MASTER MCU SLAVE MCU MISO MISO SHIFT REGISTER MOSI MOSI SHIFT REGISTER SPSCK SPSCK BAUD RATE SS SS GENERATOR V DD Figure 17-4. Full-Duplex Master-Slave Connections MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 234 Freescale Semiconductor

Transmission Formats 17.4.2 Slave Mode The SPI operates in slave mode when the SPMSTR bit is clear. In slave mode, the SPSCK pin is the input for the serial clock from the master MCU. Before a data transmission occurs, the SS pin of the slave SPI must be at logic 0. SS must remain low until the transmission is complete. See 17.7.2 Mode Fault Error. In a slave SPI module, data enters the shift register under the control of the serial clock from the master SPI module. After a byte enters the shift register of a slave SPI, it transfers to the receive data register, and the SPRF bit is set. To prevent an overflow condition, slave software then must read the receive data register before another full byte enters the shift register. The maximum frequency of the SPSCK for an SPI configured as a slave is the bus clock speed (which is twice as fast as the fastest master SPSCK clock that can be generated). The frequency of the SPSCK for an SPI configured as a slave does not have to correspond to any SPI baud rate. The baud rate only controls the speed of the SPSCK generated by an SPI configured as a master. Therefore, the frequency of the SPSCK for an SPI configured as a slave can be any frequency less than or equal to the bus speed. When the master SPI starts a transmission, the data in the slave shift register begins shifting out on the MISO pin. The slave can load its shift register with a new byte for the next transmission by writing to its transmit data register. The slave must write to its transmit data register at least one bus cycle before the master starts the next transmission. Otherwise, the byte already in the slave shift register shifts out on the MISO pin. Data written to the slave shift register during a transmission remains in a buffer until the end of the transmission. When the clock phase bit (CPHA) is set, the first edge of SPSCK starts a transmission. When CPHA is clear, the falling edge of SS starts a transmission. See 17.5 Transmission Formats. NOTE SPSCK must be in the proper idle state before the slave is enabled to prevent SPSCK from appearing as a clock edge. 17.5 Transmission Formats During an SPI transmission, data is simultaneously transmitted (shifted out serially) and received (shifted in serially). A serial clock synchronizes shifting and sampling on the two serial data lines. A slave select line allows selection of an individual slave SPI device; slave devices that are not selected do not interfere with SPI bus activities. On a master SPI device, the slave select line can optionally be used to indicate multiple-master bus contention. 17.5.1 Clock Phase and Polarity Controls Software can select any of four combinations of serial clock (SPSCK) phase and polarity using two bits in the SPI control register (SPCR). The clock polarity is specified by the CPOL control bit, which selects an active high or low clock and has no significant effect on the transmission format. The clock phase (CPHA) control bit selects one of two fundamentally different transmission formats. The clock phase and polarity should be identical for the master SPI device and the communicating slave device. In some cases, the phase and polarity are changed between transmissions to allow a master device to communicate with peripheral slaves having different requirements. NOTE Before writing to the CPOL bit or the CPHA bit, disable the SPI by clearing the SPI enable bit (SPE). MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 235

Serial Peripheral Interface (SPI) Module 17.5.2 Transmission Format When CPHA = 0 Figure 17-5 shows an SPI transmission in which CPHA is logic 0. The figure should not be used as a replacement for data sheet parametric information. Two waveforms are shown for SPSCK: one for CPOL = 0 and another for CPOL = 1. The diagram may be interpreted as a master or slave timing diagram since the serial clock (SPSCK), master in/slave out (MISO), and master out/slave in (MOSI) pins are directly connected between the master and the slave. The MISO signal is the output from the slave, and the MOSI signal is the output from the master. The SS line is the slave select input to the slave. The slave SPI drives its MISO output only when its slave select input (SS) is at logic 0, so that only the selected slave drives to the master. The SS pin of the master is not shown but is assumed to be inactive. The SS pin of the master must be high or must be reconfigured as general-purpose I/O not affecting the SPI. (See 17.7.2 Mode Fault Error.) When CPHA = 0, the first SPSCK edge is the MSB capture strobe. Therefore, the slave must begin driving its data before the first SPSCK edge, and a falling edge on the SS pin is used to start the slave data transmission. The slave’s SS pin must be toggled back to high and then low again between each byte transmitted as shown in Figure 17-6. SPSCK CYCLE # 1 2 3 4 5 6 7 8 FOR REFERENCE SPSCK; CPOL = 0 SPSCK; CPOL =1 MOSI MSB BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 LSB FROM MASTER MISO MSB BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 LSB FROM SLAVE SS; TO SLAVE CAPTURE STROBE Figure 17-5. Transmission Format (CPHA = 0) MISO/MOSI BYTE 1 BYTE 2 BYTE 3 MASTER SS SLAVE SS CPHA = 0 SLAVE SS CPHA = 1 Figure 17-6. CPHA/SS Timing When CPHA = 0 for a slave, the falling edge of SS indicates the beginning of the transmission. This causes the SPI to leave its idle state and begin driving the MISO pin with the MSB of its data. Once the transmission begins, no new data is allowed into the shift register from the transmit data register. Therefore, the SPI data register of the slave must be loaded with transmit data before the falling edge of SS. Any data written after the falling edge is stored in the transmit data register and transferred to the shift register after the current transmission. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 236 Freescale Semiconductor

Transmission Formats 17.5.3 Transmission Format When CPHA = 1 Figure 17-7 shows an SPI transmission in which CPHA is logic 1. The figure should not be used as a replacement for data sheet parametric information. Two waveforms are shown for SPSCK: one for CPOL = 0 and another for CPOL = 1. The diagram may be interpreted as a master or slave timing diagram since the serial clock (SPSCK), master in/slave out (MISO), and master out/slave in (MOSI) pins are directly connected between the master and the slave. The MISO signal is the output from the slave, and the MOSI signal is the output from the master. The SS line is the slave select input to the slave. The slave SPI drives its MISO output only when its slave select input (SS) is at logic 0, so that only the selected slave drives to the master. The SS pin of the master is not shown but is assumed to be inactive. The SS pin of the master must be high or must be reconfigured as general-purpose I/O not affecting the SPI. (See 17.7.2 Mode Fault Error.) When CPHA = 1, the master begins driving its MOSI pin on the first SPSCK edge. Therefore, the slave uses the first SPSCK edge as a start transmission signal. The SS pin can remain low between transmissions. This format may be preferable in systems having only one master and only one slave driving the MISO data line. SPSCK CYCLE # 1 2 3 4 5 6 7 8 FOR REFERENCE SPSCK; CPOL = 0 SPSCK; CPOL =1 MOSI MSB BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 LSB FROM MASTER MISO FROM SLAVE MSB BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 LSB SS; TO SLAVE CAPTURE STROBE Figure 17-7. Transmission Format (CPHA = 1) When CPHA = 1 for a slave, the first edge of the SPSCK indicates the beginning of the transmission. This causes the SPI to leave its idle state and begin driving the MISO pin with the MSB of its data. Once the transmission begins, no new data is allowed into the shift register from the transmit data register. Therefore, the SPI data register of the slave must be loaded with transmit data before the first edge of SPSCK. Any data written after the first edge is stored in the transmit data register and transferred to the shift register after the current transmission. 17.5.4 Transmission Initiation Latency When the SPI is configured as a master (SPMSTR = 1), writing to the SPDR starts a transmission. CPHA has no effect on the delay to the start of the transmission, but it does affect the initial state of the SPSCK signal. When CPHA = 0, the SPSCK signal remains inactive for the first half of the first SPSCK cycle. When CPHA = 1, the first SPSCK cycle begins with an edge on the SPSCK line from its inactive to its active level. The SPI clock rate (selected by SPR1:SPR0) affects the delay from the write to SPDR and the start of the SPI transmission. (See Figure 17-8.) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 237

Serial Peripheral Interface (SPI) Module WRITE TO SPDR INITIATION DELAY BUS CLOCK MOSI MSB BIT 6 BIT 5 SPSCK CPHA = 1 SPSCK CPHA = 0 SPSCK CYCLE 1 2 3 NUMBER INITIATION DELAY FROM WRITE SPDR TO TRANSFER BEGIN WRITE TO SPDR BUS CLOCK SPSCK = INTERNAL CLOCK ÷ 2; EARLIEST 2 POSSIBLE START POINTS WRITE LATEST TO SPDR BUS CLOCK EARLIEST SPSCK = INTERNAL CLOCK ÷ 8; LATEST 8 POSSIBLE START POINTS WRITE TO SPDR BUS CLOCK EARLIEST SPSCK = INTERNAL CLOCK ÷ 32; LATEST 32 POSSIBLE START POINTS WRITE TO SPDR BUS CLOCK EARLIEST SPSCK = INTERNAL CLOCK ÷ 128; LATEST 128 POSSIBLE START POINTS Figure 17-8. Transmission Start Delay (Master) The internal SPI clock in the master is a free-running derivative of the internal MCU clock. To conserve power, it is enabled only when both the SPE and SPMSTR bits are set. SPSCK edges occur halfway through the low time of the internal MCU clock. Since the SPI clock is free-running, it is uncertain where the write to the SPDR occurs relative to the slower SPSCK. This uncertainty causes the variation in the initiation delay shown in Figure 17-8. This delay is no longer than a single SPI bit time. That is, the maximum delay is two MCU bus cycles for DIV2, eight MCU bus cycles for DIV8, 32 MCU bus cycles for DIV32, and 128 MCU bus cycles for DIV128. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 238 Freescale Semiconductor

Queuing Transmission Data 17.6 Queuing Transmission Data The double-buffered transmit data register allows a data byte to be queued and transmitted. For an SPI configured as a master, a queued data byte is transmitted immediately after the previous transmission has completed. The SPI transmitter empty flag (SPTE) indicates when the transmit data buffer is ready to accept new data. Write to the transmit data register only when the SPTE bit is high. Figure 17-9 shows the timing associated with doing back-to-back transmissions with the SPI (SPSCK has CPHA: CPOL = 1:0). WRITE TO SPDR 1 3 8 SPTE 2 5 10 SPSCK CPHA:CPOL = 1:0 MOSI MSBBIT BIT BIT BIT BIT BITLSBMSBBIT BIT BIT BIT BIT BITLSBMSBBIT BIT BIT 6 5 4 3 2 1 6 5 4 3 2 1 6 5 4 BYTE 1 BYTE 2 BYTE 3 SPRF 4 9 READ SPSCR 6 11 READ SPDR 7 12 1 CPU WRITES BYTE 1 TO SPDR, CLEARING SPTE BIT. 7 CPU READS SPDR, CLEARING SPRF BIT. 2 BYTE 1 TRANSFERS FROM TRANSMIT DATA 8 CPU WRITES BYTE 3 TO SPDR, QUEUEING BYTE REGISTER TO SHIFT REGISTER, SETTING SPTE BIT. 3 AND CLEARING SPTE BIT. 9 SECOND INCOMING BYTE TRANSFERS FROM SHIFT 3 CPU WRITES BYTE 2 TO SPDR, QUEUEING BYTE 2 REGISTER TO RECEIVE DATA REGISTER, SETTING AND CLEARING SPTE BIT. SPRF BIT. 4 FIRST INCOMING BYTE TRANSFERS FROM SHIFT 10 BYTE 3 TRANSFERS FROM TRANSMIT DATA REGISTER TO RECEIVE DATA REGISTER, SETTING REGISTER TO SHIFT REGISTER, SETTING SPTE BIT. SPRF BIT. 11 CPU READS SPSCR WITH SPRF BIT SET. 5 BYTE 2 TRANSFERS FROM TRANSMIT DATA 12 CPU READS SPDR, CLEARING SPRF BIT. REGISTER TO SHIFT REGISTER, SETTING SPTE BIT. 6 CPU READS SPSCR WITH SPRF BIT SET. Figure 17-9. SPRF/SPTE CPU Interrupt Timing The transmit data buffer allows back-to-back transmissions without the slave precisely timing its writes between transmissions as in a system with a single data buffer. Also, if no new data is written to the data buffer, the last value contained in the shift register is the next data word to be transmitted. For an idle master or idle slave that has no data loaded into its transmit buffer, the SPTE is set again no more than two bus cycles after the transmit buffer empties into the shift register. This allows the user to queue up a 16-bit value to send. For an already active slave, the load of the shift register cannot occur until the transmission is completed. This implies that a back-to-back write to the transmit data register is not possible. The SPTE indicates when the next write can occur. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 239

Serial Peripheral Interface (SPI) Module 17.7 Error Conditions The following flags signal SPI error conditions: (cid:129) Overflow (OVRF) — Failing to read the SPI data register before the next full byte enters the shift register sets the OVRF bit. The new byte does not transfer to the receive data register, and the unread byte still can be read. OVRF is in the SPI status and control register. (cid:129) Mode fault error (MODF) — The MODF bit indicates that the voltage on the slave select pin (SS) is inconsistent with the mode of the SPI. MODF is in the SPI status and control register. 17.7.1 Overflow Error The overflow flag (OVRF) becomes set if the receive data register still has unread data from a previous transmission when the capture strobe of bit 1 of the next transmission occurs. The bit 1 capture strobe occurs in the middle of SPSCK cycle 7 (see Figure 17-5 and Figure 17-7.) If an overflow occurs, all data received after the overflow and before the OVRF bit is cleared does not transfer to the receive data register and does not set the SPI receiver full bit (SPRF). The unread data that transferred to the receive data register before the overflow occurred can still be read. Therefore, an overflow error always indicates the loss of data. Clear the overflow flag by reading the SPI status and control register and then reading the SPI data register. OVRF generates a receiver/error CPU interrupt request if the error interrupt enable bit (ERRIE) is also set. The SPRF, MODF, and OVRF interrupts share the same CPU interrupt vector (see Figure 17-12.) It is not possible to enable MODF or OVRF individually to generate a receiver/error CPU interrupt request. However, leaving MODFEN low prevents MODF from being set. If the CPU SPRF interrupt is enabled and the OVRF interrupt is not, watch for an overflow condition. Figure 17-10 shows how it is possible to miss an overflow. The first part of Figure 17-10 shows how it is possible to read the SPSCR and SPDR to clear the SPRF without problems. However, as illustrated by the second transmission example, the OVRF bit can be set in between the time that SPSCR and SPDR are read. BYTE 1 BYTE 2 BYTE 3 BYTE 4 1 4 6 8 SPRF OVRF READ 2 5 SPSCR READ 3 7 SPDR 1 BYTE 1 SETS SPRF BIT. 5 CPU READS SPSCR WITH SPRF BIT SET AND OVRF BIT CLEAR. 2 CPU READS SPSCR WITH SPRF BIT SET AND OVRF BIT CLEAR. 6 BYTE 3 SETS OVRF BIT. BYTE 3 IS LOST. 3 CPU READS BYTE 1 IN SPDR, 7 CPU READS BYTE 2 IN SPDR, CLEARING SPRF BIT, CLEARING SPRF BIT. BUT NOT OVRF BIT. 4 BYTE 2 SETS SPRF BIT. 8 BYTE 4 FAILS TO SET SPRF BIT BECAUSE OVRF BIT IS NOT CLEARED. BYTE 4 IS LOST. Figure 17-10. Missed Read of Overflow Condition MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 240 Freescale Semiconductor

Error Conditions In this case, an overflow can be missed easily. Since no more SPRF interrupts can be generated until this OVRF is serviced, it is not obvious that bytes are being lost as more transmissions are completed. To prevent this, either enable the OVRF interrupt or do another read of the SPSCR following the read of the SPDR. This ensures that the OVRF was not set before the SPRF was cleared and that future transmissions can set the SPRF bit. Figure 17-11 illustrates this process. Generally, to avoid this second SPSCR read, enable the OVRF to the CPU by setting the ERRIE bit. 17.7.2 Mode Fault Error Setting the SPMSTR bit selects master mode and configures the SPSCK and MOSI pins as outputs and the MISO pin as an input. Clearing SPMSTR selects slave mode and configures the SPSCK and MOSI pins as inputs and the MISO pin as an output. The mode fault bit, MODF, becomes set any time the state of the slave select pin, SS, is inconsistent with the mode selected by SPMSTR. To prevent SPI pin contention and damage to the MCU, a mode fault error occurs if: (cid:129) The SS pin of a slave SPI goes high during a transmission (cid:129) The SS pin of a master SPI goes low at any time For the MODF flag to be set, the mode fault error enable bit (MODFEN) must be set. Clearing the MODFEN bit does not clear the MODF flag but does prevent MODF from being set again after MODF is cleared. BYTE 1 BYTE 2 BYTE 3 BYTE 4 SPI RECEIVE 1 5 7 11 COMPLETE SPRF OVRF READ 2 4 6 9 12 14 SPSCR READ 3 8 10 13 SPDR 1 BYTE 1 SETS SPRF BIT. 8 CPU READS BYTE 2 IN SPDR, CLEARING SPRF BIT. 2 CPU READS SPSCR WITH SPRF BIT SET AND OVRF BIT CLEAR. 9 CPU READS SPSCR AGAIN TO CHECK OVRF BIT. 3 CPU READS BYTE 1 IN SPDR, CLEARING SPRF BIT. 10 CPU READS BYTE 2 SPDR, CLEARING OVRF BIT. 4 CPU READS SPSCR AGAIN TO CHECK OVRF BIT. 11 BYTE 4 SETS SPRF BIT. 5 BYTE 2 SETS SPRF BIT. 12 CPU READS SPSCR. 6 CPU READS SPSCR WITH SPRF BIT SET 13 CPU READS BYTE 4 IN SPDR, AND OVRF BIT CLEAR. CLEARING SPRF BIT. 7 BYTE 3 SETS OVRF BIT. BYTE 3 IS LOST. 14 CPU READS SPSCR AGAIN TO CHECK OVRF BIT. Figure 17-11. Clearing SPRF When OVRF Interrupt Is Not Enabled MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 241

Serial Peripheral Interface (SPI) Module MODF generates a receiver/error CPU interrupt request if the error interrupt enable bit (ERRIE) is also set. The SPRF, MODF, and OVRF interrupts share the same CPU interrupt vector. (See Figure 17-12.) It is not possible to enable MODF or OVRF individually to generate a receiver/error CPU interrupt request. However, leaving MODFEN low prevents MODF from being set. In a master SPI with the mode fault enable bit (MODFEN) set, the mode fault flag (MODF) is set if SS goes to logic 0. A mode fault in a master SPI causes the following events to occur: (cid:129) If ERRIE = 1, the SPI generates an SPI receiver/error CPU interrupt request. (cid:129) The SPE bit is cleared. (cid:129) The SPTE bit is set. (cid:129) The SPI state counter is cleared. (cid:129) The data direction register of the shared I/O port regains control of port drivers. NOTE To prevent bus contention with another master SPI after a mode fault error, clear all SPI bits of the data direction register of the shared I/O port before enabling the SPI. When configured as a slave (SPMSTR = 0), the MODF flag is set if SS goes high during a transmission. When CPHA = 0, a transmission begins when SS goes low and ends once the incoming SPSCK goes back to its idle level following the shift of the eighth data bit. When CPHA = 1, the transmission begins when the SPSCK leaves its idle level and SS is already low. The transmission continues until the SPSCK returns to its idle level following the shift of the last data bit. See 17.5 Transmission Formats. NOTE Setting the MODF flag does not clear the SPMSTR bit. The SPMSTR bit has no function when SPE = 0. Reading SPMSTR when MODF = 1 shows the difference between a MODF occurring when the SPI is a master and when it is a slave. When CPHA = 0, a MODF occurs if a slave is selected (SS is at logic 0) and later unselected (SS is at logic 1) even if no SPSCK is sent to that slave. This happens because SS at logic 0 indicates the start of the transmission (MISO driven out with the value of MSB) for CPHA = 0. When CPHA = 1, a slave can be selected and then later unselected with no transmission occurring. Therefore, MODF does not occur since a transmission was never begun. In a slave SPI (MSTR = 0), the MODF bit generates an SPI receiver/error CPU interrupt request if the ERRIE bit is set. The MODF bit does not clear the SPE bit or reset the SPI in any way. Software can abort the SPI transmission by clearing the SPE bit of the slave. NOTE A logic 1 voltage on the SS pin of a slave SPI puts the MISO pin in a high impedance state. Also, the slave SPI ignores all incoming SPSCK clocks, even if it was already in the middle of a transmission. To clear the MODF flag, read the SPSCR with the MODF bit set and then write to the SPCR register. This entire clearing mechanism must occur with no MODF condition existing or else the flag is not cleared. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 242 Freescale Semiconductor

Interrupts 17.8 Interrupts Four SPI status flags can be enabled to generate CPU interrupt requests. See Table 17-2. Table 17-2. SPI Interrupts Flag Request SPTE SPI transmitter CPU interrupt request Transmitter empty (SPTIE=1, SPE=1) SPRF SPI receiver CPU interrupt request Receiver full (SPRIE=1) OVRF SPI receiver/error interrupt request Overflow (ERRIE=1) MODF SPI receiver/error interrupt request Mode fault (ERRIE=1) Reading the SPI status and control register with SPRF set and then reading the receive data register clears SPRF. The clearing mechanism for the SPTE flag is always just a write to the transmit data register. The SPI transmitter interrupt enable bit (SPTIE) enables the SPTE flag to generate transmitter CPU interrupt requests, provided that the SPI is enabled (SPE = 1). The SPI receiver interrupt enable bit (SPRIE) enables the SPRF bit to generate receiver CPU interrupt requests, regardless of the state of the SPE bit. See Figure 17-12. The error interrupt enable bit (ERRIE) enables both the MODF and OVRF bits to generate a receiver/error CPU interrupt request. The mode fault enable bit (MODFEN) can prevent the MODF flag from being set so that only the OVRF bit is enabled by the ERRIE bit to generate receiver/error CPU interrupt requests. NOT AVAILABLE SPTE SPTIE SPE SPI TRANSMITTER CPU INTERRUPT REQUEST NOT AVAILABLE SPRIE SPRF SPI RECEIVER/ERROR CPU INTERRUPT REQUEST ERRIE MODF OVRF Figure 17-12. SPI Interrupt Request Generation MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 243

Serial Peripheral Interface (SPI) Module The following sources in the SPI status and control register can generate CPU interrupt requests: (cid:129) SPI receiver full bit (SPRF) — The SPRF bit becomes set every time a byte transfers from the shift register to the receive data register. If the SPI receiver interrupt enable bit, SPRIE, is also set, SPRF generates an SPI receiver/error CPU interrupt request. (cid:129) SPI transmitter empty (SPTE) — The SPTE bit becomes set every time a byte transfers from the transmit data register to the shift register. If the SPI transmit interrupt enable bit, SPTIE, is also set, SPTE generates an SPTE CPU interrupt request. 17.9 Resetting the SPI Any system reset completely resets the SPI. Partial resets occur whenever the SPI enable bit (SPE) is low. Whenever SPE is low, the following occurs: (cid:129) The SPTE flag is set. (cid:129) Any transmission currently in progress is aborted. (cid:129) The shift register is cleared. (cid:129) The SPI state counter is cleared, making it ready for a new complete transmission. (cid:129) All the SPI port logic is defaulted back to being general-purpose I/O. These items are reset only by a system reset: (cid:129) All control bits in the SPCR register (cid:129) All control bits in the SPSCR register (MODFEN, ERRIE, SPR1, and SPR0) (cid:129) The status flags SPRF, OVRF, and MODF By not resetting the control bits when SPE is low, the user can clear SPE between transmissions without having to set all control bits again when SPE is set back high for the next transmission. By not resetting the SPRF, OVRF, and MODF flags, the user can still service these interrupts after the SPI has been disabled. The user can disable the SPI by writing 0 to the SPE bit. The SPI can also be disabled by a mode fault occurring in an SPI that was configured as a master with the MODFEN bit set. 17.10 Low-Power Modes The WAIT and STOP instructions put the MCU in low power-consumption standby modes. 17.10.1 Wait Mode The SPI module remains active after the execution of a WAIT instruction. In wait mode the SPI module registers are not accessible by the CPU. Any enabled CPU interrupt request from the SPI module can bring the MCU out of wait mode. If SPI module functions are not required during wait mode, reduce power consumption by disabling the SPI module before executing the WAIT instruction. To exit wait mode when an overflow condition occurs, enable the OVRF bit to generate CPU interrupt requests by setting the error interrupt enable bit (ERRIE). See 17.8 Interrupts. 17.10.2 Stop Mode The SPI module is inactive after the execution of a STOP instruction. The STOP instruction does not affect register conditions. SPI operation resumes after an external interrupt. If stop mode is exited by reset, any transfer in progress is aborted, and the SPI is reset. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 244 Freescale Semiconductor

SPI During Break Interrupts 17.11 SPI During Break Interrupts The system integration module (SIM) controls whether status bits in other modules can be cleared during the break state. The BCFE bit in the SIM break flag control register (SBFCR) enables software to clear status bits during the break state. See Chapter 16 System Integration Module (SIM). To allow software to clear status bits during a break interrupt, write a logic 1 to the BCFE bit. If a status bit is cleared during the break state, it remains cleared when the MCU exits the break state. To protect status bits during the break state, write a logic 0 to the BCFE bit. With BCFE at logic 0 (its default state), software can read and write I/O registers during the break state without affecting status bits. Some status bits have a 2-step read/write clearing procedure. If software does the first step on such a bit before the break, the bit cannot change during the break state as long as BCFE is at logic 0. After the break, doing the second step clears the status bit. Since the SPTE bit cannot be cleared during a break with the BCFE bit cleared, a write to the transmit data register in break mode does not initiate a transmission nor is this data transferred into the shift register. Therefore, a write to the SPDR in break mode with the BCFE bit cleared has no effect. 17.12 I/O Signals The SPI module has five I/O pins and shares four of them with a parallel I/O port. They are: (cid:129) MISO — Data received (cid:129) MOSI — Data transmitted (cid:129) SPSCK — Serial clock (cid:129) SS — Slave select (cid:129) CGND — Clock ground (internally connected to V ) SS The SPI has limited inter-integrated circuit (I2C) capability (requiring software support) as a master in a single-master environment. To communicate with I2C peripherals, MOSI becomes an open-drain output when the SPWOM bit in the SPI control register is set. In I2C communication, the MOSI and MISO pins are connected to a bidirectional pin from the I2C peripheral and through a pullup resistor to V . DD 17.12.1 MISO (Master In/Slave Out) MISO is one of the two SPI module pins that transmits serial data. In full duplex operation, the MISO pin of the master SPI module is connected to the MISO pin of the slave SPI module. The master SPI simultaneously receives data on its MISO pin and transmits data from its MOSI pin. Slave output data on the MISO pin is enabled only when the SPI is configured as a slave. The SPI is configured as a slave when its SPMSTR bit is logic 0 and its SS pin is at logic 0. To support a multiple-slave system, a logic 1 on the SS pin puts the MISO pin in a high-impedance state. When enabled, the SPI controls data direction of the MISO pin regardless of the state of the data direction register of the shared I/O port. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 245

Serial Peripheral Interface (SPI) Module 17.12.2 MOSI (Master Out/Slave In) MOSI is one of the two SPI module pins that transmits serial data. In full-duplex operation, the MOSI pin of the master SPI module is connected to the MOSI pin of the slave SPI module. The master SPI simultaneously transmits data from its MOSI pin and receives data on its MISO pin. When enabled, the SPI controls data direction of the MOSI pin regardless of the state of the data direction register of the shared I/O port. 17.12.3 SPSCK (Serial Clock) The serial clock synchronizes data transmission between master and slave devices. In a master MCU, the SPSCK pin is the clock output. In a slave MCU, the SPSCK pin is the clock input. In full-duplex operation, the master and slave MCUs exchange a byte of data in eight serial clock cycles. When enabled, the SPI controls data direction of the SPSCK pin regardless of the state of the data direction register of the shared I/O port. 17.12.4 SS (Slave Select) The SS pin has various functions depending on the current state of the SPI. For an SPI configured as a slave, the SS is used to select a slave. For CPHA = 0, the SS is used to define the start of a transmission. (See 17.5 Transmission Formats.) Since it is used to indicate the start of a transmission, the SS must be toggled high and low between each byte transmitted for the CPHA = 0 format. However, it can remain low between transmissions for the CPHA = 1 format. See Figure 17-13. MISO/MOSI BYTE 1 BYTE 2 BYTE 3 MASTER SS SLAVE SS CPHA = 0 SLAVE SS CPHA = 1 Figure 17-13. CPHA/SS Timing When an SPI is configured as a slave, the SS pin is always configured as an input. It cannot be used as a general-purpose I/O regardless of the state of the MODFEN control bit. However, the MODFEN bit can still prevent the state of the SS from creating a MODF error. See 17.13.2 SPI Status and Control Register. NOTE A logic 1 voltage on the SS pin of a slave SPI puts the MISO pin in a high-impedance state. The slave SPI ignores all incoming SPSCK clocks, even if it was already in the middle of a transmission. When an SPI is configured as a master, the SS input can be used in conjunction with the MODF flag to prevent multiple masters from driving MOSI and SPSCK. (See 17.7.2 Mode Fault Error.) For the state of the SS pin to set the MODF flag, the MODFEN bit in the SPSCK register must be set. If the MODFEN bit is low for an SPI master, the SS pin can be used as a general-purpose I/O under the control of the data direction register of the shared I/O port. With MODFEN high, it is an input-only pin to the SPI regardless of the state of the data direction register of the shared I/O port. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 246 Freescale Semiconductor

I/O Registers The CPU can always read the state of the SS pin by configuring the appropriate pin as an input and reading the port data register. See Table 17-3. Table 17-3. SPI Configuration SPE SPMSTR MODFEN SPI Configuration State of SS Logic General-purpose I/O; 0 X(1)) X Not enabled SS ignored by SPI 1 0 X Slave Input-only to SPI General-purpose I/O; 1 1 0 Master without MODF SS ignored by SPI 1 1 1 Master with MODF Input-only to SPI 1. X = Don’t care 17.12.5 CGND (Clock Ground) CGND is the ground return for the serial clock pin, SPSCK, and the ground for the port output buffers. It is internally connected to V as shown in Table 17-1. SS 17.13 I/O Registers Three registers control and monitor SPI operation: (cid:129) SPI control register (SPCR) (cid:129) SPI status and control register (SPSCR) (cid:129) SPI data register (SPDR) 17.13.1 SPI Control Register The SPI control register: (cid:129) Enables SPI module interrupt requests (cid:129) Configures the SPI module as master or slave (cid:129) Selects serial clock polarity and phase (cid:129) Configures the SPSCK, MOSI, and MISO pins as open-drain outputs (cid:129) Enables the SPI module Address: $0010 Bit 7 6 5 4 3 2 1 Bit 0 Read: SPRIE R SPMSTR CPOL CPHA SPWOM SPE SPTIE Write: Reset: 0 0 1 0 1 0 0 0 R = Reserved Figure 17-14. SPI Control Register (SPCR) SPRIE — SPI Receiver Interrupt Enable Bit This read/write bit enables CPU interrupt requests generated by the SPRF bit. The SPRF bit is set when a byte transfers from the shift register to the receive data register. Reset clears the SPRIE bit. 1 = SPRF CPU interrupt requests enabled 0 = SPRF CPU interrupt requests disabled MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 247

Serial Peripheral Interface (SPI) Module SPMSTR — SPI Master Bit This read/write bit selects master mode operation or slave mode operation. Reset sets the SPMSTR bit. 1 = Master mode 0 = Slave mode CPOL — Clock Polarity Bit This read/write bit determines the logic state of the SPSCK pin between transmissions. (See Figure 17-5 and Figure 17-7.) To transmit data between SPI modules, the SPI modules must have identical CPOL values. Reset clears the CPOL bit. CPHA — Clock Phase Bit This read/write bit controls the timing relationship between the serial clock and SPI data. (See Figure 17-5 and Figure 17-7.) To transmit data between SPI modules, the SPI modules must have identical CPHA values. When CPHA = 0, the SS pin of the slave SPI module must be set to logic 1 between bytes. (See Figure 17-13.) Reset sets the CPHA bit. SPWOM — SPI Wired-OR Mode Bit This read/write bit disables the pullup devices on pins SPSCK, MOSI, and MISO so that those pins become open-drain outputs. 1 = Wired-OR SPSCK, MOSI, and MISO pins 0 = Normal push-pull SPSCK, MOSI, and MISO pins SPE — SPI Enable This read/write bit enables the SPI module. Clearing SPE causes a partial reset of the SPI. (See 17.9 Resetting the SPI.) Reset clears the SPE bit. 1 = SPI module enabled 0 = SPI module disabled SPTIE— SPI Transmit Interrupt Enable This read/write bit enables CPU interrupt requests generated by the SPTE bit. SPTE is set when a byte transfers from the transmit data register to the shift register. Reset clears the SPTIE bit. 1 = SPTE CPU interrupt requests enabled 0 = SPTE CPU interrupt requests disabled 17.13.2 SPI Status and Control Register The SPI status and control register contains flags to signal these conditions: (cid:129) Receive data register full (cid:129) Failure to clear SPRF bit before next byte is received (overflow error) (cid:129) Inconsistent logic level on SS pin (mode fault error) (cid:129) Transmit data register empty The SPI status and control register also contains bits that perform these functions: (cid:129) Enable error interrupts (cid:129) Enable mode fault error detection (cid:129) Select master SPI baud rate MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 248 Freescale Semiconductor

I/O Registers Address: $0011 Bit 7 6 5 4 3 2 1 Bit 0 Read: SPRF OVRF MODF SPTE ERRIE MODFEN SPR1 SPR0 Write: Reset: 0 0 0 0 1 0 0 0 =Unimplemented Figure 17-15. SPI Status and Control Register (SPSCR) SPRF — SPI Receiver Full Bit This clearable, read-only flag is set each time a byte transfers from the shift register to the receive data register. SPRF generates a CPU interrupt request if the SPRIE bit in the SPI control register is set also. During an SPRF CPU interrupt, the CPU clears SPRF by reading the SPI status and control register with SPRF set and then reading the SPI data register. Reset clears the SPRF bit. 1 = Receive data register full 0 = Receive data register not full ERRIE — Error Interrupt Enable Bit This read/write bit enables the MODF and OVRF bits to generate CPU interrupt requests. Reset clears the ERRIE bit. 1 = MODF and OVRF can generate CPU interrupt requests 0 = MODF and OVRF cannot generate CPU interrupt requests OVRF — Overflow Bit This clearable, read-only flag is set if software does not read the byte in the receive data register before the next full byte enters the shift register. In an overflow condition, the byte already in the receive data register is unaffected, and the byte that shifted in last is lost. Clear the OVRF bit by reading the SPI status and control register with OVRF set and then reading the receive data register. Reset clears the OVRF bit. 1 = Overflow 0 = No overflow MODF — Mode Fault Bit This clearable, read-only flag is set in a slave SPI if the SS pin goes high during a transmission with the MODFEN bit set. In a master SPI, the MODF flag is set if the SS pin goes low at any time with the MODFEN bit set. Clear the MODF bit by reading the SPI status and control register (SPSCR) with MODF set and then writing to the SPI control register (SPCR). Reset clears the MODF bit. 1 = SS pin at inappropriate logic level 0 = SS pin at appropriate logic level SPTE — SPI Transmitter Empty Bit This clearable, read-only flag is set each time the transmit data register transfers a byte into the shift register. SPTE generates an SPTE CPU interrupt request or an SPTE DMA service request if the SPTIE bit in the SPI control register is set also. NOTE Do not write to the SPI data register unless the SPTE bit is high. During an SPTE CPU interrupt, the CPU clears the SPTE bit by writing to the transmit data register. Reset sets the SPTE bit. 1 = Transmit data register empty 0 = Transmit data register not empty MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 249

Serial Peripheral Interface (SPI) Module MODFEN — Mode Fault Enable Bit This read/write bit, when set to 1, allows the MODF flag to be set. If the MODF flag is set, clearing the MODFEN does not clear the MODF flag. If the SPI is enabled as a master and the MODFEN bit is low, then the SS pin is available as a general-purpose I/O. If the MODFEN bit is set, then this pin is not available as a general-purpose I/O. When the SPI is enabled as a slave, the SS pin is not available as a general-purpose I/O regardless of the value of MODFEN. See 17.12.4 SS (Slave Select). If the MODFEN bit is low, the level of the SS pin does not affect the operation of an enabled SPI configured as a master. For an enabled SPI configured as a slave, having MODFEN low only prevents the MODF flag from being set. It does not affect any other part of SPI operation. See 17.7.2 Mode Fault Error. SPR1 and SPR0 — SPI Baud Rate Select Bits In master mode, these read/write bits select one of four baud rates as shown in Table 17-4. SPR1 and SPR0 have no effect in slave mode. Reset clears SPR1 and SPR0. Table 17-4. SPI Master Baud Rate Selection SPR1 and SPR0 Baud Rate Divisor (BD) 00 2 01 8 10 32 11 128 Use this formula to calculate the SPI baud rate: CGMOUT Baud rate = -------------------------- 2×BD where: CGMOUT = base clock output of the clock generator module (CGM) BD = baud rate divisor 17.13.3 SPI Data Register The SPI data register consists of the read-only receive data register and the write-only transmit data register. Writing to the SPI data register writes data into the transmit data register. Reading the SPI data register reads data from the receive data register. The transmit data and receive data registers are separate registers that can contain different values. See Figure 17-3. Address: $0012 Bit 7 6 5 4 3 2 1 Bit 0 Read: R7 R6 R5 R4 R3 R2 R1 R0 Write: T7 T6 T5 T4 T3 T2 T1 T0 Reset: Unaffected by reset Figure 17-16. SPI Data Register (SPDR) R7–R0/T7–T0 — Receive/Transmit Data Bits NOTE Do not use read-modify-write instructions on the SPI data register since the register read is not the same as the register written. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 250 Freescale Semiconductor

Chapter 18 Timebase Module (TBM) 18.1 Introduction This section describes the timebase module (TBM). The TBM will generate periodic interrupts at user selectable rates using a counter clocked by the external clock source. This TBM version uses 15 divider stages, eight of which are user selectable. A configuration option bit to select an additional 128 divide of the external clock source can be selected. See Chapter 5 Configuration Register (CONFIG) 18.2 Features Features of the TBM module include: (cid:129) External clock or an additional divide-by-128 selected by configuration option bit as clock source (cid:129) Software configurable periodic interrupts with divide-by: 8, 16, 32, 64, 128, 2048, 8192, and 32768 taps of the selected clock source (cid:129) Configurable for operation during stop mode to allow periodic wakeup from stop 18.3 Functional Description This module can generate a periodic interrupt by dividing the clock source supplied from the clock generator module, CGMXCLK. The counter is initialized to all 0s when TBON bit is cleared. The counter, shown in Figure 18-1, starts counting when the TBON bit is set. When the counter overflows at the tap selected by TBR2–TBR0, the TBIF bit gets set. If the TBIE bit is set, an interrupt request is sent to the CPU. The TBIF flag is cleared by writing a 1 to the TACK bit. The first time the TBIF flag is set after enabling the timebase module, the interrupt is generated at approximately half of the overflow period. Subsequent events occur at the exact period. The timebase module may remain active after execution of the STOP instruction if the crystal oscillator has been enabled to operate during stop mode through the OSCENINSTOP bit in the configuration register. The timebase module can be used in this mode to generate a periodic wakeup from stop mode. 18.4 Interrupts The timebase module can periodically interrupt the CPU with a rate defined by the selected TBMCLK and the select bits TBR2–TBR0. When the timebase counter chain rolls over, the TBIF flag is set. If the TBIE bit is set, enabling the timebase interrupt, the counter chain overflow will generate a CPU interrupt request. NOTE Interrupts must be acknowledged by writing a logic 1 to the TACK bit. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 251

Timebase Module (TBM) TBMCLKSEL FROM CONFIG2 0 TBMCLK CGMXCLK DIVIDE BY 128 1 FROM CGM MODULE PRESCALER TBON ÷ 2 ÷ 2 ÷ 2 ÷ 2 ÷ 2 ÷ 2 ÷ 2 TBMINT 2 1 0 K ÷ 2 ÷ 2 ÷ 2 ÷ 2 ÷ 2 ÷ 2 ÷ 2 ÷ 2 BR BR BR AC T T T T TBIF TBIE 0 0 0 R 0 0 1 0 1 0 0 1 1 L 1 0 0 E S 1 0 1 1 1 0 1 1 1 Figure 18-1. Timebase Block Diagram 18.5 TBM Interrupt Rate The interrupt rate is determined by the equation: 1 Divider t = --------------------------- = ----------------------- TBMRATE f f TBMRATE TBMCLK where: f = Frequency supplied from the clock generator (CGM) module TBMCLK Divider = Divider value as determined by TBR2–TBR0 settings, see Table 18-1 MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 252 Freescale Semiconductor

Low-Power Modes Table 18-1. Timebase Divider Selection Divider Tap TBR2 TBR1 TBR0 TMBCLKSEL 0 1 0 0 0 32,768 4,194,304 0 0 1 8192 1,048,576 0 1 0 2048 262144 0 1 1 128 16,384 1 0 0 64 8192 1 0 1 32 4096 1 1 0 16 2048 1 1 1 8 1024 As an example, a clock source of 4.9152 MHz, with the TMCLKSEL set for divide-by-128 and the TBR2–TBR0 set to {011}, the divider tap is1 and the interrupt rate calculates to: 1/(4.9152 x 106/128) = 26 μs NOTE Do not change TBR2–TBR0 bits while the timebase is enabled (TBON = 1). 18.6 Low-Power Modes The WAIT and STOP instructions put the MCU in low power- consumption standby modes. 18.6.1 Wait Mode The timebase module remains active after execution of the WAIT instruction. In wait mode the timebase register is not accessible by the CPU. If the timebase functions are not required during wait mode, reduce the power consumption by stopping the timebase before executing the WAIT instruction. 18.6.2 Stop Mode The timebase module may remain active after execution of the STOP instruction if the internal clock generator has been enabled to operate during stop mode through the OSCENINSTOP bit in the configuration register. The timebase module can be used in this mode to generate a periodic wakeup from stop mode. If the internal clock generator has not been enabled to operate in stop mode, the timebase module will not be active during stop mode. In stop mode, the timebase register is not accessible by the CPU. If the timebase functions are not required during stop mode, reduce power consumption by disabling the timebase module before executing the STOP instruction. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 253

Timebase Module (TBM) 18.7 Timebase Control Register The timebase has one register, the timebase control register (TBCR), which is used to enable the timebase interrupts and set the rate. Address: $001C Bit 7 6 5 4 3 2 1 Bit 0 Read: TBIF 0 TBR2 TBR1 TBR0 TBIE TBON R Write: TACK Reset: 0 0 0 0 0 0 0 0 = Unimplemented R = Reserved Figure 18-2. Timebase Control Register (TBCR) TBIF — Timebase Interrupt Flag This read-only flag bit is set when the timebase counter has rolled over. 1 = Timebase interrupt pending 0 = Timebase interrupt not pending TBR2–TBR0 — Timebase Divider Selection Bits These read/write bits select the tap in the counter to be used for timebase interrupts as shown in Table 18-1. NOTE Do not change TBR2–TBR0 bits while the timebase is enabled (TBON = 1). TACK— Timebase Acknowledge Bit The TACK bit is a write-only bit and always reads as 0. Writing a logic 1 to this bit clears TBIF, the timebase interrupt flag bit. Writing a logic 0 to this bit has no effect. 1 = Clear timebase interrupt flag 0 = No effect TBIE — Timebase Interrupt Enabled Bit This read/write bit enables the timebase interrupt when the TBIF bit becomes set. Reset clears the TBIE bit. 1 = Timebase interrupt is enabled. 0 = Timebase interrupt is disabled. TBON — Timebase Enabled Bit This read/write bit enables the timebase. Timebase may be turned off to reduce power consumption when its function is not necessary. The counter can be initialized by clearing and then setting this bit. Reset clears the TBON bit. 1 = Timebase is enabled. 0 = Timebase is disabled and the counter initialized to 0s. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 254 Freescale Semiconductor

Chapter 19 Timer Interface Module (TIM) 19.1 Introduction This section describes the timer interface (TIM) module. The TIM is a two-channel timer that provides a timing reference with input capture, output compare, and pulse-width-modulation functions. Figure 19-1 is a block diagram of the TIM. This particular MCU has two timer interface modules which are denoted as TIM1 and TIM2. PRESCALER SELECT INTERNAL PRESCALER BUS CLOCK TSTOP PS2 PS1 PS0 TRST 16-BIT COUNTER TOF INTERRUPT LOGIC TOIE 16-BIT COMPARATOR TMODH:TMODL TOV0 CHANNEL 0 ELS0B ELS0A CH0MAX PORT T[1,2]CH0 LOGIC 16-BIT COMPARATOR TCH0H:TCH0L CH0F 16-BIT LATCH INTERRUPT CH0IE LOGIC MS0A MS0B TOV1 CHANNEL 1 ELS1B ELS1A CH1MAX PORT T[1,2]CH1 S LOGIC U B 16-BIT COMPARATOR L A N TCH1H:TCH1L CH1F R TE 16-BIT LATCH INTERRUPT N I CH1IE LOGIC MS1A Figure 19-1. TIM Block Diagram MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 255

Timer Interface Module (TIM) INTERNAL BUS M68HC08 CPU REGCISPTUERS ARITUHNMIET T(AICL/ULO)GIC PROGRAMMMOADBULLEE TIMEBASE DDRA PORTA PPTTAA70//KKBBDD70–(1) PTB7/AD7 SINGLE BREAKPOINT CONTROL AND STATUS REGISTERS — 64 BYTES PTB6/AD6 BREAK MODULE PTB5/AD5 USER FLASH — 15,872 BYTES LOWD-UVAOLL TVAOGLETA INGHEIBIT DDRB PORTB PPTTBB43//AADD43 MODULE PTB2/AD2 USER RAM — 1024 BYTES PTB1/AD1 8-BIT KEYBOARD PTB0/AD0 MONITOR ROM — 350 BYTES INTERRUPT MODULE PTC6(1) PTC5(1) FLASH PROGRAMMING ROUTINES ROM — 406 BYTES 2-CHANNEL TIMER USER FLASH VECTOR SPACE — 44 BYTES INTERFACE MODULE 1 DDRC PORTC PPPTTTCCC432(((111))),,, (((222))) 2-CHANNEL TIMER INTERFACE MODULE 2 PTC1/CANRX(1), (2) CLOCK GENERATOR MODULE PTC0/CAN (1), (2) TX OSC1 1–8 MHz OSCILLATOR ENHANCED SERIAL OSC2 COMUNICATIONS PTD7/T2CH1(1) PHASE LOCKED LOOP INTERFACE MODULE PTD6/T2CH0(1) CGMXFC PTD5/T1CH1(1) RST(3) SYSTEM INTEGRATION COPMRPOUPTEERRL YO MPEORDAUTLIENG DDRD PORTD PPPTTTDDD243///MTS1POCSSHCI(0K1()(11)) MODULE SERIAL PERIPHERAL PTD1/MISO(1) INTERFACE MODULE PTD0/SS(1) IRQ(3) SINGLE EXTERNAL INTERRUPT MODULE PTE5–PTE2 VVDDAD//VVREFH 10-CBOITN AVNEARLTOEGR- TMOO-DDUIGLIETAL MONITOR MODULE DDRE PORTE PPTTEE10//RTxxDD DDAD REFL MEMORY MAP MODULE POWER-ON RESET MODULE SECURITY CONFIGURATION MODULE VDD REGISTER 1–2 VSS POWER MODULE V DDA V MONITOR MODE ENTRY SSA MSCAN08 MODULE MODULE 1. Ports are software configurable with pullup device if input port. 2. Higher current drive port pins 3. Pin contains integrated pullup device Figure 19-2. Block Diagram Highlighting TIM Block and Pins MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 256 Freescale Semiconductor

Features 19.2 Features Features of the TIM include: (cid:129) Two input capture/output compare channels: – Rising-edge, falling-edge, or any-edge input capture trigger – Set, clear, or toggle output compare action (cid:129) Buffered and unbuffered pulse-width-modulation (PWM) signal generation (cid:129) Programmable TIM clock input with 7-frequency internal bus clock prescaler selection (cid:129) Free-running or modulo up-count operation (cid:129) Toggle any channel pin on overflow (cid:129) TIM counter stop and reset bits 19.3 Pin Name Conventions The text that follows describes both timers, TIM1 and TIM2. The TIM input/output (I/O) pin names are T[1,2]CH0 (timer channel 0) and T[1,2]CH1 (timer channel 1), where “1” is used to indicate TIM1 and “2” is used to indicate TIM2. The two TIMs share four I/O pins with four port D I/O port pins. The full names of the TIM I/O pins are listed in Table 19-1. The generic pin names appear in the text that follows. Table 19-1. Pin Name Conventions TIM Generic Pin Names: T[1,2]CH0 T[1,2]CH1 TIM1 PTD4/T1CH0 PTD5/T1CH1 Full TIM Pin Names: TIM2 PTD6/T2CH0 PTD7/T2CH1 NOTE References to either timer 1 or timer 2 may be made in the following text by omitting the timer number. For example, TCH0 may refer generically to T1CH0 and T2CH0, and TCH1 may refer to T1CH1 and T2CH1. 19.4 Functional Description Figure 19-1 shows the structure of the TIM. The central component of the TIM is the 16-bit TIM counter that can operate as a free-running counter or a modulo up-counter. The TIM counter provides the timing reference for the input capture and output compare functions. The TIM counter modulo registers, TMODH:TMODL, control the modulo value of the TIM counter. Software can read the TIM counter value at any time without affecting the counting sequence. The two TIM channels (per timer) are programmable independently as input capture or output compare channels. If a channel is configured as input capture, then an internal pullup device may be enabled for that channel. See 13.6.3 Port D Input Pullup Enable Register. Figure 19-3 summarizes the timer registers. NOTE References to either timer 1 or timer 2 may be made in the following text by omitting the timer number. For example, TSC may generically refer to both T1SC and T2SC. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 257

Timer Interface Module (TIM) Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: TOF 0 0 Timer 1 Status and Control TOIE TSTOP PS2 PS1 PS0 $0020 Register (T1SC) Write: 0 TRST See page 265. Reset: 0 0 1 0 0 0 0 0 Read: Bit 15 14 13 12 11 10 9 Bit 8 Timer 1 Counter $0021 Register High (T1CNTH) Write: See page 266. Reset: 0 0 0 0 0 0 0 0 Read: Bit 7 6 5 4 3 2 1 Bit 0 Timer 1 Counter $0022 Register Low (T1CNTL) Write: See page 266. Reset: 0 0 0 0 0 0 0 0 Read: Timer 1 Counter Modulo Bit 15 14 13 12 11 10 9 Bit 8 $0023 Register High (T1MODH) Write: See page 267. Reset: 1 1 1 1 1 1 1 1 Read: Timer 1 Counter Modulo Bit 7 6 5 4 3 2 1 Bit 0 $0024 Register Low (T1MODL) Write: See page 267. Reset: 1 1 1 1 1 1 1 1 Read: CH0F Timer 1 Channel 0 Status and CH0IE MS0B MS0A ELS0B ELS0A TOV0 CH0MAX $0025 Control Register (T1SC0) Write: 0 See page 267. Reset: 0 0 0 0 0 0 0 0 Read: Timer 1 Channel 0 Bit 15 14 13 12 11 10 9 Bit 8 $0026 Register High (T1CH0H) Write: See page 270. Reset: Indeterminate after reset Read: Timer 1 Channel 0 Bit 7 6 5 4 3 2 1 Bit 0 $0027 Register Low (T1CH0L) Write: See page 270. Reset: Indeterminate after reset Read: CH1F 0 Timer 1 Channel 1 Status and CH1IE MS1A ELS1B ELS1A TOV1 CH1MAX $0028 Control Register (T1SC1) Write: 0 See page 267. Reset: 0 0 0 0 0 0 0 0 Read: Timer 1 Channel 1 Bit 15 14 13 12 11 10 9 Bit 8 $0029 Register High (T1CH1H) Write: See page 270. Reset: Indeterminate after reset Read: Timer 1 Channel 1 Bit 7 6 5 4 3 2 1 Bit 0 $002A Register Low (T1CH1L) Write: See page 270. Reset: Indeterminate after reset Read: TOF 0 0 Timer 2 Status and Control TOIE TSTOP PS2 PS1 PS0 $002B Register (T2SC) Write: 0 TRST See page 265. Reset: 0 0 1 0 0 0 0 0 Read: Bit 15 14 13 12 11 10 9 Bit 8 Timer 2 Counter $002C Register High (T2CNTH) Write: See page 266. Reset: 0 0 0 0 0 0 0 0 =Unimplemented Figure 19-3. TIM I/O Register Summary (Sheet 1 of 2) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 258 Freescale Semiconductor

Functional Description Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 7 6 5 4 3 2 1 Bit 0 Timer 2 Counter $002D Register Low (T2CNTL) Write: See page 266. Reset: 0 0 0 0 0 0 0 0 Read: Timer 2 Counter Modulo Bit 15 14 13 12 11 10 9 Bit 8 $002E Register High (T2MODH) Write: See page 267. Reset: 1 1 1 1 1 1 1 1 Read: Timer 2 Counter Modulo Bit 7 6 5 4 3 2 1 Bit 0 $002F Register Low (T2MODL) Write: See page 267. Reset: 1 1 1 1 1 1 1 1 Read: CH0F Timer 2 Channel 0 Status and CH0IE MS0B MS0A ELS0B ELS0A TOV0 CH0MAX $0030 Control Register (T2SC0) Write: 0 See page 267. Reset: 0 0 0 0 0 0 0 0 Read: Timer 2 Channel 0 Bit 15 14 13 12 11 10 9 Bit 8 $0031 Register High (T2CH0H) Write: See page 270. Reset: Indeterminate after reset Read: Timer 2 Channel 0 Bit 7 6 5 4 3 2 1 Bit 0 $0032 Register Low (T2CH0L) Write: See page 270. Reset: Indeterminate after reset Read: CH1F 0 Timer 2 Channel 1 Status and CH1IE MS1A ELS1B ELS1A TOV1 CH1MAX $0033 Control Register (T2SC1) Write: 0 See page 267. Reset: 0 0 0 0 0 0 0 0 Read: Timer 2 Channel 1 Bit 15 14 13 12 11 10 9 Bit 8 $0034 Register High (T2CH1H) Write: See page 270. Reset: Indeterminate after reset Read: Timer 2 Channel 1 Bit 7 6 5 4 3 2 1 Bit 0 $0035 Register Low (T2CH1L) Write: See page 270. Reset: Indeterminate after reset =Unimplemented Figure 19-3. TIM I/O Register Summary (Sheet 2 of 2) 19.4.1 TIM Counter Prescaler The TIM clock source can be one of the seven prescaler outputs. The prescaler generates seven clock rates from the internal bus clock. The prescaler select bits, PS[2:0], in the TIM status and control register select the TIM clock source. 19.4.2 Input Capture With the input capture function, the TIM can capture the time at which an external event occurs. When an active edge occurs on the pin of an input capture channel, the TIM latches the contents of the TIM counter into the TIM channel registers, TCHxH:TCHxL. The polarity of the active edge is programmable. Input captures can generate TIM CPU interrupt requests. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 259

Timer Interface Module (TIM) 19.4.3 Output Compare With the output compare function, the TIM can generate a periodic pulse with a programmable polarity, duration, and frequency. When the counter reaches the value in the registers of an output compare channel, the TIM can set, clear, or toggle the channel pin. Output compares can generate TIM CPU interrupt requests. 19.4.3.1 Unbuffered Output Compare Any output compare channel can generate unbuffered output compare pulses as described in 19.4.3 Output Compare. The pulses are unbuffered because changing the output compare value requires writing the new value over the old value currently in the TIM channel registers. An unsynchronized write to the TIM channel registers to change an output compare value could cause incorrect operation for up to two counter overflow periods. For example, writing a new value before the counter reaches the old value but after the counter reaches the new value prevents any compare during that counter overflow period. Also, using a TIM overflow interrupt routine to write a new, smaller output compare value may cause the compare to be missed. The TIM may pass the new value before it is written. Use the following methods to synchronize unbuffered changes in the output compare value on channel x: (cid:129) When changing to a smaller value, enable channel x output compare interrupts and write the new value in the output compare interrupt routine. The output compare interrupt occurs at the end of the current output compare pulse. The interrupt routine has until the end of the counter overflow period to write the new value. (cid:129) When changing to a larger output compare value, enable TIM overflow interrupts and write the new value in the TIM overflow interrupt routine. The TIM overflow interrupt occurs at the end of the current counter overflow period. Writing a larger value in an output compare interrupt routine (at the end of the current pulse) could cause two output compares to occur in the same counter overflow period. 19.4.3.2 Buffered Output Compare Channels 0 and 1 can be linked to form a buffered output compare channel whose output appears on the TCH0 pin. The TIM channel registers of the linked pair alternately control the output. Setting the MS0B bit in TIM channel 0 status and control register (TSC0) links channel 0 and channel 1. The output compare value in the TIM channel 0 registers initially controls the output on the TCH0 pin. Writing to the TIM channel 1 registers enables the TIM channel 1 registers to synchronously control the output after the TIM overflows. At each subsequent overflow, the TIM channel registers (0 or 1) that control the output are the ones written to last. TSC0 controls and monitors the buffered output compare function, and TIM channel 1 status and control register (TSC1) is unused. While the MS0B bit is set, the channel 1 pin, TCH1, is available as a general-purpose I/O pin. NOTE In buffered output compare operation, do not write new output compare values to the currently active channel registers. User software should track the currently active channel to prevent writing a new value to the active channel. Writing to the active channel registers is the same as generating unbuffered output compares. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 260 Freescale Semiconductor

Functional Description 19.4.4 Pulse Width Modulation (PWM) By using the toggle-on-overflow feature with an output compare channel, the TIM can generate a PWM signal. The value in the TIM counter modulo registers determines the period of the PWM signal. The channel pin toggles when the counter reaches the value in the TIM counter modulo registers. The time between overflows is the period of the PWM signal. As Figure 19-4 shows, the output compare value in the TIM channel registers determines the pulse width of the PWM signal. The time between overflow and output compare is the pulse width. Program the TIM to clear the channel pin on output compare if the state of the PWM pulse is logic 1. Program the TIM to set the pin if the state of the PWM pulse is logic 0. The value in the TIM counter modulo registers and the selected prescaler output determines the frequency of the PWM output. The frequency of an 8-bit PWM signal is variable in 256 increments. Writing $00FF (255) to the TIM counter modulo registers produces a PWM period of 256 times the internal bus clock period if the prescaler select value is $000. See 19.9.1 TIM Status and Control Register. OVERFLOW OVERFLOW OVERFLOW PERIOD PULSE WIDTH TCHx OUTPUT OUTPUT OUTPUT COMPARE COMPARE COMPARE Figure 19-4. PWM Period and Pulse Width The value in the TIM channel registers determines the pulse width of the PWM output. The pulse width of an 8-bit PWM signal is variable in 256 increments. Writing $0080 (128) to the TIM channel registers produces a duty cycle of 128/256 or 50%. 19.4.4.1 Unbuffered PWM Signal Generation Any output compare channel can generate unbuffered PWM pulses as described in 19.4.4 Pulse Width Modulation (PWM). The pulses are unbuffered because changing the pulse width requires writing the new pulse width value over the old value currently in the TIM channel registers. An unsynchronized write to the TIM channel registers to change a pulse width value could cause incorrect operation for up to two PWM periods. For example, writing a new value before the counter reaches the old value but after the counter reaches the new value prevents any compare during that PWM period. Also, using a TIM overflow interrupt routine to write a new, smaller pulse width value may cause the compare to be missed. The TIM may pass the new value before it is written. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 261

Timer Interface Module (TIM) Use the following methods to synchronize unbuffered changes in the PWM pulse width on channel x: (cid:129) When changing to a shorter pulse width, enable channel x output compare interrupts and write the new value in the output compare interrupt routine. The output compare interrupt occurs at the end of the current pulse. The interrupt routine has until the end of the PWM period to write the new value. (cid:129) When changing to a longer pulse width, enable TIM overflow interrupts and write the new value in the TIM overflow interrupt routine. The TIM overflow interrupt occurs at the end of the current PWM period. Writing a larger value in an output compare interrupt routine (at the end of the current pulse) could cause two output compares to occur in the same PWM period. NOTE In PWM signal generation, do not program the PWM channel to toggle on output compare. Toggling on output compare prevents reliable 0% duty cycle generation and removes the ability of the channel to self-correct in the event of software error or noise. Toggling on output compare also can cause incorrect PWM signal generation when changing the PWM pulse width to a new, much larger value. 19.4.4.2 Buffered PWM Signal Generation Channels 0 and 1 can be linked to form a buffered PWM channel whose output appears on the TCH0 pin. The TIM channel registers of the linked pair alternately control the pulse width of the output. Setting the MS0B bit in TIM channel 0 status and control register (TSC0) links channel 0 and channel 1. The TIM channel 0 registers initially control the pulse width on the TCH0 pin. Writing to the TIM channel 1 registers enables the TIM channel 1 registers to synchronously control the pulse width at the beginning of the next PWM period. At each subsequent overflow, the TIM channel registers (0 or 1) that control the pulse width are the ones written to last. TSC0 controls and monitors the buffered PWM function, and TIM channel 1 status and control register (TSC1) is unused. While the MS0B bit is set, the channel 1 pin, TCH1, is available as a general-purpose I/O pin. NOTE In buffered PWM signal generation, do not write new pulse width values to the currently active channel registers. User software should track the currently active channel to prevent writing a new value to the active channel. Writing to the active channel registers is the same as generating unbuffered PWM signals. 19.4.4.3 PWM Initialization To ensure correct operation when generating unbuffered or buffered PWM signals, use the following initialization procedure: 1. In the TIM status and control register (TSC): a. Stop the TIM counter by setting the TIM stop bit, TSTOP. b. Reset the TIM counter and prescaler by setting the TIM reset bit, TRST. 2. In the TIM counter modulo registers (TMODH:TMODL), write the value for the required PWM period. 3. In the TIM channel x registers (TCHxH:TCHxL), write the value for the required pulse width. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 262 Freescale Semiconductor

Interrupts 4. In TIM channel x status and control register (TSCx): a. Write 0:1 (for unbuffered output compare or PWM signals) or 1:0 (for buffered output compare or PWM signals) to the mode select bits, MSxB:MSxA. See Table 19-3. b. Write 1 to the toggle-on-overflow bit, TOVx. c. Write 1:0 (to clear output on compare) or 1:1 (to set output on compare) to the edge/level select bits, ELSxB:ELSxA. The output action on compare must force the output to the complement of the pulse width level. See Table 19-3. NOTE In PWM signal generation, do not program the PWM channel to toggle on output compare. Toggling on output compare prevents reliable 0% duty cycle generation and removes the ability of the channel to self-correct in the event of software error or noise. Toggling on output compare can also cause incorrect PWM signal generation when changing the PWM pulse width to a new, much larger value. 5. In the TIM status control register (TSC), clear the TIM stop bit, TSTOP. Setting MS0B links channels 0 and 1 and configures them for buffered PWM operation. The TIM channel 0 registers (TCH0H:TCH0L) initially control the buffered PWM output. TIM status control register 0 (TSCR0) controls and monitors the PWM signal from the linked channels. Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIM overflows. Subsequent output compares try to force the output to a state it is already in and have no effect. The result is a 0% duty cycle output. Setting the channel x maximum duty cycle bit (CHxMAX) and setting the TOVx bit generates a 100% duty cycle output. See 19.9.4 TIM Channel Status and Control Registers. 19.5 Interrupts The following TIM sources can generate interrupt requests: (cid:129) TIM overflow flag (TOF) — The TOF bit is set when the TIM counter reaches the modulo value programmed in the TIM counter modulo registers. The TIM overflow interrupt enable bit, TOIE, enables TIM overflow CPU interrupt requests. TOF and TOIE are in the TIM status and control register. (cid:129) TIM channel flags (CH1F:CH0F) — The CHxF bit is set when an input capture or output compare occurs on channel x. Channel x TIM CPU interrupt requests are controlled by the channel x interrupt enable bit, CHxIE. Channel x TIM CPU interrupt requests are enabled when CHxIE = 1. CHxF and CHxIE are in the TIM channel x status and control register. 19.6 Low-Power Modes The WAIT and STOP instructions put the MCU in low power- consumption standby modes. 19.6.1 Wait Mode The TIM remains active after the execution of a WAIT instruction. In wait mode, the TIM registers are not accessible by the CPU. Any enabled CPU interrupt request from the TIM can bring the MCU out of wait mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 263

Timer Interface Module (TIM) If TIM functions are not required during wait mode, reduce power consumption by stopping the TIM before executing the WAIT instruction. 19.6.2 Stop Mode The TIM is inactive after the execution of a STOP instruction. The STOP instruction does not affect register conditions or the state of the TIM counter. TIM operation resumes when the MCU exits stop mode after an external interrupt. 19.7 TIM During Break Interrupts A break interrupt stops the TIM counter. The system integration module (SIM) controls whether status bits in other modules can be cleared during the break state. The BCFE bit in the SIM break flag control register (SBFCR) enables software to clear status bits during the break state. See 16.7.3 Break Flag Control Register. To allow software to clear status bits during a break interrupt, write a logic 1 to the BCFE bit. If a status bit is cleared during the break state, it remains cleared when the MCU exits the break state. To protect status bits during the break state, write a logic 0 to the BCFE bit. With BCFE at logic 0 (its default state), software can read and write I/O registers during the break state without affecting status bits. Some status bits have a 2-step read/write clearing procedure. If software does the first step on such a bit before the break, the bit cannot change during the break state as long as BCFE is at logic 0. After the break, doing the second step clears the status bit. 19.8 I/O Signals Port D shares four of its pins with the TIM. The four TIM channel I/O pins are T1CH0, T1CH1, T2CH0, and T2CH1 as described in 19.3 Pin Name Conventions. Each channel I/O pin is programmable independently as an input capture pin or an output compare pin. T1CH0 and T2CH0 can be configured as buffered output compare or buffered PWM pins. 19.9 I/O Registers NOTE References to either timer 1 or timer 2 may be made in the following text by omitting the timer number. For example, TSC may generically refer to both T1SC AND T2SC. These I/O registers control and monitor operation of the TIM: (cid:129) TIM status and control register (TSC) (cid:129) TIM counter registers (TCNTH:TCNTL) (cid:129) TIM counter modulo registers (TMODH:TMODL) (cid:129) TIM channel status and control registers (TSC0 and TSC1) (cid:129) TIM channel registers (TCH0H:TCH0L, TCH1H:TCH1L) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 264 Freescale Semiconductor

I/O Registers 19.9.1 TIM Status and Control Register The TIM status and control register (TSC): (cid:129) Enables TIM overflow interrupts (cid:129) Flags TIM overflows (cid:129) Stops the TIM counter (cid:129) Resets the TIM counter (cid:129) Prescales the TIM counter clock Address: T1SC, $0020 and T2SC, $002B Bit 7 6 5 4 3 2 1 Bit 0 Read: TOF 0 0 TOIE TSTOP PS2 PS1 PS0 Write: 0 TRST Reset: 0 0 1 0 0 0 0 0 = Unimplemented Figure 19-5. TIM Status and Control Register (TSC) TOF — TIM Overflow Flag Bit This read/write flag is set when the TIM counter reaches the modulo value programmed in the TIM counter modulo registers. Clear TOF by reading the TIM status and control register when TOF is set and then writing a logic 0 to TOF. If another TIM overflow occurs before the clearing sequence is complete, then writing logic 0 to TOF has no effect. Therefore, a TOF interrupt request cannot be lost due to inadvertent clearing of TOF. Reset clears the TOF bit. Writing a logic 1 to TOF has no effect. 1 = TIM counter has reached modulo value 0 = TIM counter has not reached modulo value TOIE — TIM Overflow Interrupt Enable Bit This read/write bit enables TIM overflow interrupts when the TOF bit becomes set. Reset clears the TOIE bit. 1 = TIM overflow interrupts enabled 0 = TIM overflow interrupts disabled TSTOP — TIM Stop Bit This read/write bit stops the TIM counter. Counting resumes when TSTOP is cleared. Reset sets the TSTOP bit, stopping the TIM counter until software clears the TSTOP bit. 1 = TIM counter stopped 0 = TIM counter active NOTE Do not set the TSTOP bit before entering wait mode if the TIM is required to exit wait mode. TRST — TIM Reset Bit Setting this write-only bit resets the TIM counter and the TIM prescaler. Setting TRST has no effect on any other registers. Counting resumes from $0000. TRST is cleared automatically after the TIM counter is reset and always reads as logic 0. Reset clears the TRST bit. 1 = Prescaler and TIM counter cleared 0 = No effect NOTE Setting the TSTOP and TRST bits simultaneously stops the TIM counter at a value of $0000. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 265

Timer Interface Module (TIM) PS[2:0] — Prescaler Select Bits These read/write bits select one of the seven prescaler outputs as the input to the TIM counter as Table 19-2 shows. Reset clears the PS[2:0] bits. Table 19-2. Prescaler Selection PS2 PS1 PS0 TIM Clock Source 0 0 0 Internal bus clock ÷ 1 0 0 1 Internal bus clock ÷ 2 0 1 0 Internal bus clock ÷ 4 0 1 1 Internal bus clock ÷ 8 1 0 0 Internal bus clock ÷ 16 1 0 1 Internal bus clock ÷ 32 1 1 0 Internal bus clock ÷ 64 1 1 1 Not available 19.9.2 TIM Counter Registers The two read-only TIM counter registers contain the high and low bytes of the value in the TIM counter. Reading the high byte (TCNTH) latches the contents of the low byte (TCNTL) into a buffer. Subsequent reads of TCNTH do not affect the latched TCNTL value until TCNTL is read. Reset clears the TIM counter registers. Setting the TIM reset bit (TRST) also clears the TIM counter registers. NOTE If you read TCNTH during a break interrupt, be sure to unlatch TCNTL by reading TCNTL before exiting the break interrupt. Otherwise, TCNTL retains the value latched during the break. Address: T1CNTH, $0021 and T2CNTH, $002C Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 15 14 13 12 11 10 9 Bit 8 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 19-6. TIM Counter Registers High (TCNTH) Address: T1CNTL, $0022 and T2CNTL, $002D Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 7 6 5 4 3 2 1 Bit 0 Write: Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 19-7. TIM Counter Registers Low (TCNTL) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 266 Freescale Semiconductor

I/O Registers 19.9.3 TIM Counter Modulo Registers The read/write TIM modulo registers contain the modulo value for the TIM counter. When the TIM counter reaches the modulo value, the overflow flag (TOF) becomes set, and the TIM counter resumes counting from $0000 at the next timer clock. Writing to the high byte (TMODH) inhibits the TOF bit and overflow interrupts until the low byte (TMODL) is written. Reset sets the TIM counter modulo registers. Address: T1MODH, $0023 and T2MODH, $002E Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 15 14 13 12 11 10 9 Bit 8 Write: Reset: 1 1 1 1 1 1 1 1 Figure 19-8. TIM Counter Modulo Register High (TMODH) Address: T1MODL, $0024 and T2MODL, $002F Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 7 6 5 4 3 2 1 Bit 0 Write: Reset: 1 1 1 1 1 1 1 1 Figure 19-9. TIM Counter Modulo Register Low (TMODL) NOTE Reset the TIM counter before writing to the TIM counter modulo registers. 19.9.4 TIM Channel Status and Control Registers Each of the TIM channel status and control registers: (cid:129) Flags input captures and output compares (cid:129) Enables input capture and output compare interrupts (cid:129) Selects input capture, output compare, or PWM operation (cid:129) Selects high, low, or toggling output on output compare (cid:129) Selects rising edge, falling edge, or any edge as the active input capture trigger (cid:129) Selects output toggling on TIM overflow (cid:129) Selects 0% and 100% PWM duty cycle (cid:129) Selects buffered or unbuffered output compare/PWM operation Address: T1SC0, $0025 and T2SC0, $0030 Bit 7 6 5 4 3 2 1 Bit 0 Read: CH0F CH0IE MS0B MS0A ELS0B ELS0A TOV0 CH0MAX Write: 0 Reset: 0 0 0 0 0 0 0 0 Figure 19-10. TIM Channel 0 Status and Control Register (TSC0) Address: T1SC1, $0028 and T2SC1, $0033 Bit 7 6 5 4 3 2 1 Bit 0 Read: CH1F 0 CH1IE MS1A ELS1B ELS1A TOV1 CH1MAX Write: 0 Reset: 0 0 0 0 0 0 0 0 = Unimplemented Figure 19-11. TIM Channel 1 Status and Control Register (TSC1) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 267

Timer Interface Module (TIM) CHxF — Channel x Flag Bit When channel x is an input capture channel, this read/write bit is set when an active edge occurs on the channel x pin. When channel x is an output compare channel, CHxF is set when the value in the TIM counter registers matches the value in the TIM channel x registers. When TIM CPU interrupt requests are enabled (CHxIE = 1), clear CHxF by reading TIM channel x status and control register with CHxF set and then writing a logic 0 to CHxF. If another interrupt request occurs before the clearing sequence is complete, then writing logic 0 to CHxF has no effect. Therefore, an interrupt request cannot be lost due to inadvertent clearing of CHxF. Reset clears the CHxF bit. Writing a logic 1 to CHxF has no effect. 1 = Input capture or output compare on channel x 0 = No input capture or output compare on channel x CHxIE — Channel x Interrupt Enable Bit This read/write bit enables TIM CPU interrupt service requests on channel x. Reset clears the CHxIE bit. 1 = Channel x CPU interrupt requests enabled 0 = Channel x CPU interrupt requests disabled MSxB — Mode Select Bit B This read/write bit selects buffered output compare/PWM operation. MSxB exists only in the TIM1 channel 0 and TIM2 channel 0 status and control registers. Setting MS0B disables the channel 1 status and control register and reverts TCH1 to general-purpose I/O. Reset clears the MSxB bit. 1 = Buffered output compare/PWM operation enabled 0 = Buffered output compare/PWM operation disabled MSxA — Mode Select Bit A When ELSxB:A ≠ 00, this read/write bit selects either input capture operation or unbuffered output compare/PWM operation. See Table 19-3. 1 = Unbuffered output compare/PWM operation 0 = Input capture operation When ELSxB:A = 00, this read/write bit selects the initial output level of the TCHx pin. See Table 19-3. Reset clears the MSxA bit. 1 = Initial output level low 0 = Initial output level high NOTE Before changing a channel function by writing to the MSxB or MSxA bit, set the TSTOP and TRST bits in the TIM status and control register (TSC). ELSxB and ELSxA — Edge/Level Select Bits When channel x is an input capture channel, these read/write bits control the active edge-sensing logic on channel x. When channel x is an output compare channel, ELSxB and ELSxA control the channel x output behavior when an output compare occurs. When ELSxB and ELSxA are both clear, channel x is not connected to port D, and pin PTDx/TCHx is available as a general-purpose I/O pin. Table 19-3 shows how ELSxB and ELSxA work. Reset clears the ELSxB and ELSxA bits. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 268 Freescale Semiconductor

I/O Registers Table 19-3. Mode, Edge, and Level Selection MSxB:MSxA ELSxB:ELSxA Mode Configuration X0 00 Output Pin under port control; initial output level high X1 00 preset Pin under port control; initial output level low 00 01 Capture on rising edge only Input 00 10 Capture on falling edge only capture 00 11 Capture on rising or falling edge 01 01 Toggle output on compare Output compare 01 10 Clear output on compare or PWM 01 11 Set output on compare 1X 01 Buffered output Toggle output on compare compare 1X 10 Clear output on compare or buffered 1X 11 PWM Set output on compare NOTE Before enabling a TIM channel register for input capture operation, make sure that the PTD/TCHx pin is stable for at least two bus clocks. TOVx — Toggle On Overflow Bit When channel x is an output compare channel, this read/write bit controls the behavior of the channel x output when the TIM counter overflows. When channel x is an input capture channel, TOVx has no effect. Reset clears the TOVx bit. 1 = Channel x pin toggles on TIM counter overflow. 0 = Channel x pin does not toggle on TIM counter overflow. NOTE When TOVx is set, a TIM counter overflow takes precedence over a channel x output compare if both occur at the same time. CHxMAX — Channel x Maximum Duty Cycle Bit When the TOVx bit is at logic 1, setting the CHxMAX bit forces the duty cycle of buffered and unbuffered PWM signals to 100%. As Figure 19-12 shows, the CHxMAX bit takes effect in the cycle after it is set or cleared. The output stays at the 100% duty cycle level until the cycle after CHxMAX is cleared. OVERFLOW OVERFLOW OVERFLOW OVERFLOW OVERFLOW PERIOD TCHx OUTPUT OUTPUT OUTPUT OUTPUT COMPARE COMPARE COMPARE COMPARE CHxMAX Figure 19-12. CHxMAX Latency MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 269

Timer Interface Module (TIM) 19.9.5 TIM Channel Registers These read/write registers contain the captured TIM counter value of the input capture function or the output compare value of the output compare function. The state of the TIM channel registers after reset is unknown. In input capture mode (MSxB:MSxA = 0:0), reading the high byte of the TIM channel x registers (TCHxH) inhibits input captures until the low byte (TCHxL) is read. In output compare mode (MSxB:MSxA ≠ 0:0), writing to the high byte of the TIM channel x registers (TCHxH) inhibits output compares until the low byte (TCHxL) is written. Address: T1CH0H, $0026 and T2CH0H, $0031 Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 15 14 13 12 11 10 9 Bit 8 Write: Reset: Indeterminate after reset Figure 19-13. TIM Channel 0 Register High (TCH0H) Address: T1CH0L, $0027 and T2CH0L $0032 Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 7 6 5 4 3 2 1 Bit 0 Write: Reset: Indeterminate after reset Figure 19-14. TIM Channel 0 Register Low (TCH0L) Address: T1CH1H, $0029 and T2CH1H, $0034 Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 15 14 13 12 11 10 9 Bit 8 Write: Reset: Indeterminate after reset Figure 19-15. TIM Channel 1 Register High (TCH1H) Address: T1CH1L, $002A and T2CH1L, $0035 Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 7 6 5 4 3 2 1 Bit 0 Write: Reset: Indeterminate after reset Figure 19-16. TIM Channel 1 Register Low (TCH1L) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 270 Freescale Semiconductor

Chapter 20 Development Support 20.1 Introduction This section describes the break module, the monitor read-only memory (MON), and the monitor mode entry methods. 20.2 Break Module (BRK) The break module can generate a break interrupt that stops normal program flow at a defined address to enter a background program. Features of the break module include: (cid:129) Accessible input/output (I/O) registers during the break Interrupt (cid:129) Central processor unit (CPU) generated break interrupts (cid:129) Software-generated break interrupts (cid:129) Computer operating properly (COP) disabling during break interrupts 20.2.1 Functional Description When the internal address bus matches the value written in the break address registers, the break module issues a breakpoint signal (BKPT) to the system integration module (SIM). The SIM then causes the CPU to load the instruction register with a software interrupt instruction (SWI). The program counter vectors to $FFFC and $FFFD ($FEFC and $FEFD in monitor mode). The following events can cause a break interrupt to occur: (cid:129) A CPU generated address (the address in the program counter) matches the contents of the break address registers. (cid:129) Software writes a logic 1 to the BRKA bit in the break status and control register. When a CPU generated address matches the contents of the break address registers, the break interrupt is generated. A return-from-interrupt instruction (RTI) in the break routine ends the break interrupt and returns the microcontroller unit (MCU) to normal operation. Figure 20-1 shows the structure of the break module. Figure 20-2 provides a summary of the I/O registers. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 271

Development Support ADDRESS BUS[15:8] BREAK ADDRESS REGISTER HIGH 8-BIT COMPARATOR ADDRESS BUS[15:0] CONTROL BKPT (TO SIM) 8-BIT COMPARATOR BREAK ADDRESS REGISTER LOW ADDRESS BUS[7:0] Figure 20-1. Break Module Block Diagram Addr. Register Name Bit 7 6 5 4 3 2 1 Bit 0 Read: SBSW Break Status Register R R R R R R R $FE00 (BSR) Write: Note(1) See page 275. Reset: 0 Read: R R R R R R R R $FE02 Reserved Write: Reset: 0 0 0 0 0 0 0 0 Read: Break Flag Control BCFE R R R R R R R $FE03 Register (BFCR) Write: See page 275. Reset: 0 Read: Break Address High Bit15 Bit14 Bit13 Bit12 Bit11 Bit10 Bit9 Bit8 $FE09 Register (BRKH) Write: See page 274. Reset: 0 0 0 0 0 0 0 0 Read: Break Address Low Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 $FE0A Register (BRKL) Write: See page 274. Reset: 0 0 0 0 0 0 0 0 Read: 0 0 0 0 0 0 Break Status and Control BRKE BRKA $FE0B Register (BRKSCR) Write: See page 274. Reset: 0 0 0 0 0 0 0 0 1. Writing a logic 0 clears SBSW. =Unimplemented R =Reserved Figure 20-2. Break I/O Register Summary MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 272 Freescale Semiconductor

Break Module (BRK) When the internal address bus matches the value written in the break address registers or when software writes a logic 1 to the BRKA bit in the break status and control register, the CPU starts a break interrupt by: (cid:129) Loading the instruction register with the SWI instruction (cid:129) Loading the program counter with $FFFC and $FFFD ($FEFC and $FEFD in monitor mode) The break interrupt timing is: (cid:129) When a break address is placed at the address of the instruction opcode, the instruction is not executed until after completion of the break interrupt routine. (cid:129) When a break address is placed at an address of an instruction operand, the instruction is executed before the break interrupt. (cid:129) When software writes a logic 1 to the BRKA bit, the break interrupt occurs just before the next instruction is executed. By updating a break address and clearing the BRKA bit in a break interrupt routine, a break interrupt can be generated continuously. CAUTION A break address should be placed at the address of the instruction opcode. When software does not change the break address and clears the BRKA bit in the first break interrupt routine, the next break interrupt will not be generated after exiting the interrupt routine even when the internal address bus matches the value written in the break address registers. 20.2.1.1 Flag Protection During Break Interrupts The system integration module (SIM) controls whether or not module status bits can be cleared during the break state. The BCFE bit in the break flag control register (BFCR) enables software to clear status bits during the break state. See 16.7.3 Break Flag Control Register and the Break Interrupts subsection for each module. 20.2.1.2 TIM During Break Interrupts A break interrupt stops the timer counter. 20.2.1.3 COP During Break Interrupts The COP is disabled during a break interrupt when V is present on the RST pin. TST 20.2.2 Break Module Registers These registers control and monitor operation of the break module: (cid:129) Break status and control register (BRKSCR) (cid:129) Break address register high (BRKH) (cid:129) Break address register low (BRKL) (cid:129) Break status register (BSR) (cid:129) Break flag control register (BFCR) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 273

Development Support 20.2.2.1 Break Status and Control Register The break status and control register (BRKSCR) contains break module enable and status bits. Address: $FE0B Bit 7 6 5 4 3 2 1 Bit 0 Read: 0 0 0 0 0 0 BRKE BRKA Write: Reset: 0 0 0 0 0 0 0 0 =Unimplemented Figure 20-3. Break Status and Control Register (BRKSCR) BRKE — Break Enable Bit This read/write bit enables breaks on break address register matches. Clear BRKE by writing a logic 0 to bit 7. Reset clears the BRKE bit. 1 = Breaks enabled on 16-bit address match 0 = Breaks disabled BRKA — Break Active Bit This read/write status and control bit is set when a break address match occurs. Writing a logic 1 to BRKA generates a break interrupt. Clear BRKA by writing a logic 0 to it before exiting the break routine. Reset clears the BRKA bit. 1 = Break address match 0 = No break address match 20.2.2.2 Break Address Registers The break address registers (BRKH and BRKL) contain the high and low bytes of the desired breakpoint address. Reset clears the break address registers. Address: $FE09 Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Write: Reset: 0 0 0 0 0 0 0 0 Figure 20-4. Break Address Register High (BRKH) Address: $FE0A Bit 7 6 5 4 3 2 1 Bit 0 Read: Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Write: Reset: 0 0 0 0 0 0 0 0 Figure 20-5. Break Address Register Low (BRKL) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 274 Freescale Semiconductor

Monitor ROM (MON) 20.2.2.3 Break Status Register The break status register (BSR) contains a flag to indicate that a break caused an exit from wait mode. This register is only used in emulation mode. Address: $FE00 Bit 7 6 5 4 3 2 1 Bit 0 Read: SBSW R R R R R R R Write: Note(1) Reset: 0 R = Reserved 1. Writing a logic 0 clears SBSW. Figure 20-6. Break Status Register (BSR) SBSW — SIM Break Stop/Wait SBSW can be read within the break state SWI routine. The user can modify the return address on the stack by subtracting one from it. 1 = Wait mode was exited by break interrupt 0 = Wait mode was not exited by break interrupt 20.2.2.4 Break Flag Control Register The break control register (BFCR) contains a bit that enables software to clear status bits while the MCU is in a break state. Address: $FE03 Bit 7 6 5 4 3 2 1 Bit 0 Read: BCFE R R R R R R R Write: Reset: 0 R = Reserved Figure 20-7. Break Flag Control Register (BFCR) BCFE — Break Clear Flag Enable Bit This read/write bit enables software to clear status bits by accessing status registers while the MCU is in a break state. To clear status bits during the break state, the BCFE bit must be set. 1 = Status bits clearable during break 0 = Status bits not clearable during break 20.2.3 Low-Power Modes The WAIT and STOP instructions put the MCU in low power- consumption standby modes. If enabled, the break module will remain enabled in wait and stop modes. However, since the internal address bus does not increment in these modes, a break interrupt will never be triggered. 20.3 Monitor ROM (MON) This subsection describes the monitor ROM (MON) and the monitor mode entry methods. The monitor ROM allows complete testing of the microcontroller unit (MCU) through a single-wire interface with a host MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 275

Development Support computer. Monitor mode entry can be achieved without use of the higher test voltage, V , as long as TST vector addresses $FFFE and $FFFF are blank, thus reducing the hardware requirements for in-circuit programming. Features of the monitor ROM include: (cid:129) Normal user-mode pin functionality (cid:129) One pin dedicated to serial communication between monitor read-only memory (ROM) and host computer (cid:129) Standard mark/space non-return-to-zero (NRZ) communication with host computer (cid:129) Standard communication baud rate (7200 @ 8-MHz crystal frequency) (cid:129) Execution of code in random-access memory (RAM) or FLASH (cid:129) FLASH memory security feature(1) (cid:129) FLASH memory programming interface (cid:129) 350 bytes monitor ROM code size ($FE20 to $FF7D) (cid:129) Monitor mode entry without high voltage, V , if reset vector is blank ($FFFE and $FFFF contain TST $FF) (cid:129) Normal monitor mode entry if high voltage is applied to IRQ 20.3.1 Functional Description Figure 20-8 shows a simplified diagram of the monitor mode. The monitor ROM receives and executes commands from a host computer. Figure 20-9 and Figure 20-10 show example circuits used to enter monitor mode and communicate with a host computer via a standard RS-232 interface. Simple monitor commands can access any memory address. In monitor mode, the MCU can execute code downloaded into RAM by a host computer while most MCU pins retain normal operating mode functions. All communication between the host computer and the MCU is through the PTA0 pin. A level-shifting and multiplexing interface is required between PTA0 and the host computer. PTA0 is used in a wired-OR configuration and requires a pullup resistor. Table 20-1 shows the pin conditions for entering monitor mode. As specified in the table, monitor mode may be entered after a power-on reset (POR) and will allow communication at 7200 baud provided one of the following sets of conditions is met: (cid:129) If $FFFE and $FFFF does not contain $FF (programmed state): – The external clock is 4 MHz (7200 baud) – PTB4 = low – IRQ = V TST (cid:129) If $FFFE and $FFFF do not contain $FF (programmed state): – The external clock is 8 MHz (7200 baud) – PTB4 = high – IRQ = V TST (cid:129) If $FFFE and $FFFF contain $FF (erased state): – The external clock is 8 MHz (7200 baud) – IRQ = V (this can be implemented through the internal IRQ pullup) or V DD SS 1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult for unauthorized users. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 276 Freescale Semiconductor

Monitor ROM (MON) POR RESET NO YES IRQ = V ? TST CONDITIONS PTA0 = 1, PTA0 = 1, PTA1 = 0, FROM Table20-1 NO NO PTA1 = 0, RESET PTB0 = 1, AND VECTOR BLANK? PTB1 = 0? YES YES FORCED NORMAL NORMAL INVALID MONITOR MODE USER MODE MONITOR MODE USER MODE HOST SENDS 8 SECURITY BYTES IS RESET YES POR? NO ARE ALL YES NO SECURITY BYTES CORRECT? ENABLE FLASH DISABLE FLASH MONITOR MODE ENTRY DEBUGGING AND FLASH EXECUTE PROGRAMMING MONITOR CODE (IF FLASH IS ENABLED) YES DOES RESET NO OCCUR? Figure 20-8. Simplified Monitor Mode Entry Flowchart MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 277

Development Support MC68HC908GZ16 V DD N.C. RST V DD 47 pF V OSC2 DDA MAX232 V DD 0.1 μF 10 MΩ 1 C1+ VCC 16 27 pF V + + OSC1 DD 1 μF 1 μF 8 MHz 10 k 3 15 C1– GND 1 μF PTB4 + 10 k 4 C2+ V+ 2 1 kΩ IRQ PTB0 + 1 μF 6 VDD 10 k V– 9.1 V PTB1 5 C2– 1 μF 10 k + 10 kΩ PTA1 DB9 74HC125 2 7 10 6 5 PTA0 74HC125 VSSA 3 8 9 2 3 4 V SS 1 5 Figure 20-9. Normal Monitor Mode Circuit MC68HC908GZ16 V DD N.C. RST V DD 47 pF V OSC2 DDA MAX232 V DD 0.1 μF 10 MΩ 1 C1+ VCC 16 27 pF + + OSC1 1 μF 1 μF 8 MHz 3 15 C1– GND 1 μF + PTB4 N.C. 4 C2+ V+ 2 N.C. IRQ PTB0 N.C. + 1 μF 6 VDD PTB1 N.C. V– 5 C2– 1 μF 10 k + 10 kΩ PTA1 DB9 74HC125 2 7 10 6 5 PTA0 74HC125 VSSA 3 8 9 2 3 4 V SS 5 1 Figure 20-10. Forced Monitor Mode MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 278 Freescale Semiconductor

F re Table 20-1. Monitor Mode Signal Requirements and Options e s c a Serial Mode Communication le Divider S Reset Communication Selection Speed e Mode IRQ RST PLL COP Comments m Vector External Bus Baud ic PTA0 PTA1 PTB0 PTB1 PTB4 o Clock Frequency Rate n d u — X GND X X X X X X X X X X X Reset condition c to r V DD VTST or X 1 0 1 0 0 OFF Disabled 4 MHz 2 MHz 7200 V Normal TST M C Monitor VDD 6 8H VTST or X 1 0 1 0 1 OFF Disabled 8 MHz 2 MHz 7200 C VTST 9 0 8 V G Forced DD $FF Z1 Monitor or VDD (blank) 1 0 X X X OFF Disabled 8 MHz 2 MHz 7200 6 GND (cid:129) M C VDD VDD Not 6 8 User or or $FF X X X X X X Enabled X X X H C GND VTST 9 0 8 MON08 GZ Function VTST RST — COM SSEL MOD0 MOD1 DIV4 — — OSC1 — — 8 [6] [4] [8] [10] [12] [14] [16] [13] D [Pin No.] a ta S 21.. CPTomA0m munuiscta htiaovne s ap epeudll uinp trhees itsatbolre t ois V aDnD e ixna mmopnleit otor mobotdaein. a baud rate of 7200. Baud rate using external oscillator is bus frequency / 278. h e 3. External clock is an 4.0 MHz or 8.0 MHz crystal on OSC1 and OSC2 or a canned oscillator on OSC1. e t, R 45.. XM O= Nd0o8n ’tp cina rreefers to P&E Microcomputer Systems’ MON08-Cyclone 2 by 8-pin connector. e v . 4 NC 1 2 GND NC 3 4 RST NC 5 6 IRQ NC 7 8 PTA0 M o n NC 9 10 PTA1 ito r NC 11 12 PTB0 R O OSC1 13 14 PTB1 M (M 2 VDD 15 16 PTB4 O 7 N 9 )

Development Support Enter monitor mode with pin configuration shown in Table 20-1 by pulling RST low and then high. The rising edge of RST latches monitor mode. Once monitor mode is latched, the values on the specified pins can change. Once out of reset, the MCU waits for the host to send eight security bytes (see 20.3.2 Security). After the security bytes, the MCU sends a break signal (10 consecutive logic 0s) to the host, indicating that it is ready to receive a command. 20.3.1.1 Normal Monitor Mode If V is applied to IRQ and PTB4 is low upon monitor mode entry, the bus frequency is a divide-by-two TST of the input clock. If PTB4 is high with V applied to IRQ upon monitor mode entry, the bus frequency TST will be a divide-by-four of the input clock. Holding the PTB4 pin low when entering monitor mode causes a bypass of a divide-by-two stage at the oscillator only if V is applied to IRQ. In this event, the TST CGMOUT frequency is equal to the CGMXCLK frequency, and the OSC1 input directly generates internal bus clocks. In this case, the OSC1 signal must have a 50% duty cycle at maximum bus frequency. When monitor mode was entered with V on IRQ, the computer operating properly (COP) is disabled TST as long as V is applied to either IRQ or RST. TST This condition states that as long as V is maintained on the IRQ pin after entering monitor mode, or if TST V is applied to RST after the initial reset to get into monitor mode (when V was applied to IRQ), TST TST then the COP will be disabled. In the latter situation, after V is applied to the RST pin, V can be TST TST removed from the IRQ pin in the interest of freeing the IRQ for normal functionality in monitor mode. 20.3.1.2 Forced Monitor Mode If entering monitor mode without high voltage on IRQ, then all port B pin requirements and conditions, including the PTB4 frequency divisor selection, are not in effect. This is to reduce circuit requirements when performing in-circuit programming. NOTE If the reset vector is blank and monitor mode is entered, the chip will see an additional reset cycle after the initial power-on reset (POR). Once the reset vector has been programmed, the traditional method of applying a voltage, V , to IRQ must be used to enter monitor mode. TST An external oscillator of 8 MHz is required for a baud rate of 7200, as the internal bus frequency is automatically set to the external frequency divided by four. When the forced monitor mode is entered the COP is always disabled regardless of the state of IRQ or RST. 20.3.1.3 Monitor Vectors In monitor mode, the MCU uses different vectors for reset, SWI (software interrupt), and break interrupt than those for user mode. The alternate vectors are in the $FE page instead of the $FF page and allow code execution from the internal monitor firmware instead of user code. Table 20-2 summarizes the differences between user mode and monitor mode. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 280 Freescale Semiconductor

Monitor ROM (MON) Table 20-2. Mode Differences Functions Modes Reset Reset Break Break SWI SWI Vector High Vector Low Vector High Vector Low Vector High Vector Low User $FFFE $FFFF $FFFC $FFFD $FFFC $FFFD Monitor $FEFE $FEFF $FEFC $FEFD $FEFC $FEFD 20.3.1.4 Data Format Communication with the monitor ROM is in standard non-return-to-zero (NRZ) mark/space data format. Transmit and receive baud rates must be identical. NEXT START START BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 STOP BIT BIT Figure 20-11. Monitor Data Format 20.3.1.5 Break Signal A start bit (logic 0) followed by nine logic 0 bits is a break signal. When the monitor receives a break signal, it drives the PTA0 pin high for the duration of two bits and then echoes back the break signal. MISSING STOP BIT APPROXIMATELY 2 BITS DELAY BEFORE ZERO ECHO 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 Figure 20-12. Break Transaction 20.3.1.6 Baud Rate The communication baud rate is controlled by the crystal frequency or external clock and the state of the PTB4 pin (when IRQ is set to V ) upon entry into monitor mode. If monitor mode was entered with V TST DD on IRQ and the reset vector blank, then the baud rate is independent of PTB4. Table 20-1 also lists external frequencies required to achieve a standard baud rate of 7200 bps. The effective baud rate is the bus frequency divided by 278. If using a crystal as the clock source, be aware of the upper frequency limit that the internal clock module can handle. See 21.7 5.0-Volt Control Timing or 21.6 3.3-Vdc Electrical Characteristics for this limit. 20.3.1.7 Commands The monitor ROM firmware uses these commands: (cid:129) READ (read memory) (cid:129) WRITE (write memory) (cid:129) IREAD (indexed read) (cid:129) IWRITE (indexed write) (cid:129) READSP (read stack pointer) (cid:129) RUN (run user program) MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 281

Development Support The monitor ROM firmware echoes each received byte back to the PTA0 pin for error checking. An 11-bit delay at the end of each command allows the host to send a break character to cancel the command. A delay of two bit times occurs before each echo and before READ, IREAD, or READSP data is returned. The data returned by a read command appears after the echo of the last byte of the command. NOTE Wait one bit time after each echo before sending the next byte. FROM HOST ADDRESS ADDRESS ADDRESS ADDRESS READ READ DATA HIGH HIGH LOW LOW 4 1 4 1 4 1 3, 2 4 ECHO RETURN Notes: 1 = Echo delay, approximately 2 bit times 2 = Data return delay, approximately 2 bit times 3 = Cancel command delay, 11 bit times 4 = Wait 1 bit time before sending next byte. Figure 20-13. Read Transaction FROM HOST ADDRESS ADDRESS ADDRESS ADDRESS WRITE WRITE DATA DATA HIGH HIGH LOW LOW 3 1 3 1 3 1 3 1 2, 3 ECHO Notes: 1 = Echo delay, approximately 2 bit times 2 = Cancel command delay, 11 bit times 3 = Wait 1 bit time before sending next byte. Figure 20-14. Write Transaction A brief description of each monitor mode command is given in Table 20-3 through Table 20-8. Table 20-3. READ (Read Memory) Command Description Read byte from memory Operand 2-byte address in high-byte:low-byte order Data Returned Returns contents of specified address Opcode $4A Command Sequence SENT TO MONITOR Address Address Address Address READ READ Data High High Low Low ECHO RETURN MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 282 Freescale Semiconductor

Monitor ROM (MON) Table 20-4. WRITE (Wri te Memory) Command Description Write byte to memory Operand 2-byte address in high-byte:low-byte order; low byte followed by data byte Data Returned None Opcode $49 Command Sequence FROM HOST ADDRESS ADDRESS ADDRESS ADDRESS WRITE WRITE HIGH HIGH LOW LOW DATA DATA ECHO Table 20-5. IREAD (Indexed Read) Command Description Read next 2 bytes in memory from last address accessed Operand 2-byte address in high byte:low byte order Data Returned Returns contents of next two addresses Opcode $1A Command Sequence FROM HOST IREAD IREAD DATA DATA ECHO RETURN Table 20-6. IWRITE (Indexed Write) Command Description Write to last address accessed + 1 Operand Single data byte Data Returned None Opcode $19 Command Sequence FROM HOST IWRITE IWRITE DATA DATA ECHO A sequence of IREAD or IWRITE commands can access a block of memory sequentially over the full 64-Kbyte memory map. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 283

Development Support Table 20-7. READSP (Read Stack Pointer) Command Description Reads stack pointer Operand None Data Returned Returns incremented stack pointer value (SP+1) in high-byte:low-byte order Opcode $0C Command Sequence FROM HOST SP SP READSP READSP HIGH LOW ECHO RETURN Table 20-8. RUN (Run User Program) Command Description Executes PULH and RTI instructions Operand None Data Returned None Opcode $28 Command Sequence FROM HOST RUN RUN ECHO The MCU executes the SWI and PSHH instructions when it enters monitor mode. The RUN command tells the MCU to execute the PULH and RTI instructions. Before sending the RUN command, the host can modify the stacked CPU registers to prepare to run the host program. The READSP command returns the incremented stack pointer value, SP + 1. The high and low bytes of the program counter are at addresses SP + 5 and SP + 6. SP HIGH BYTE OF INDEX REGISTER SP + 1 CONDITION CODE REGISTER SP + 2 ACCUMULATOR SP + 3 LOW BYTE OF INDEX REGISTER SP + 4 HIGH BYTE OF PROGRAM COUNTER SP + 5 LOW BYTE OF PROGRAM COUNTER SP + 6 SP + 7 Figure 20-15. Stack Pointer at Monitor Mode Entry MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 284 Freescale Semiconductor

Monitor ROM (MON) 20.3.2 Security A security feature discourages unauthorized reading of FLASH locations while in monitor mode. The host can bypass the security feature at monitor mode entry by sending eight security bytes that match the bytes at locations $FFF6–$FFFD. Locations $FFF6–$FFFD contain user-defined data. NOTE Do not leave locations $FFF6–$FFFD blank. For security reasons, program locations $FFF6–$FFFD even if they are not used for vectors. During monitor mode entry, the MCU waits after the power-on reset for the host to send the eight security bytes on pin PTA0. If the received bytes match those at locations $FFF6–$FFFD, the host bypasses the security feature and can read all FLASH locations and execute code from FLASH. Security remains bypassed until a power-on reset occurs. If the reset was not a power-on reset, security remains bypassed and security code entry is not required. See Figure 20-16. Upon power-on reset, if the received bytes of the security code do not match the data at locations $FFF6–$FFFD, the host fails to bypass the security feature. The MCU remains in monitor mode, but reading a FLASH location returns an invalid value and trying to execute code from FLASH causes an illegal address reset. After receiving the eight security bytes from the host, the MCU transmits a break character, signifying that it is ready to receive a command. NOTE The MCU does not transmit a break character until after the host sends the eight security bytes. V DD 4096 + 32 CGMXCLK CYCLES RST D N YTE 1 YTE 2 YTE 8 OMMA B B B C FROM HOST PA0 5 1 4 1 1 2 4 1 FROM MCU O O O K O H H H A H No1t e=s :E cho delay, approximately 2 bit times E 1 EC E 2 EC E 8 EC BRE ND EC 2 = Data return delay, approximately 2 bit times YT YT YT MA 4 = Wait 1 bit time before sending next byte B B B M O 5 = Wait until the monitor ROM runs C Figure 20-16. Monitor Mode Entry Timing To determine whether the security code entered is correct, check to see if bit 6 of RAM address $40 is set. If it is, then the correct security code has been entered and FLASH can be accessed. If the security sequence fails, the device should be reset by a power-on reset and brought up in monitor mode to attempt another entry. After failing the security sequence, the FLASH module can also be mass erased by executing an erase routine that was downloaded into internal RAM. The mass erase operation clears the security code locations so that all eight security bytes become $FF (blank). MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 285

Development Support MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 286 Freescale Semiconductor

Chapter 21 Electrical Specifications 21.1 Introduction This section contains electrical and timing specifications. 21.2 Absolute Maximum Ratings Maximum ratings are the extreme limits to which the MCU can be exposed without permanently damaging it. NOTE This device is not guaranteed to operate properly at the maximum ratings. Refer to 21.5 5-Vdc Electrical Characteristics and 21.6 3.3-Vdc Electrical Characteristics for guaranteed operating conditions. Characteristic(1) Symbol Value Unit Supply voltage VDD –0.3 to + 6.0 V Input voltage VIn VSS – 0.3 to VDD + 0.3 V Maximum current per pin excluding those specified below I ± 15 mA Maximum current for pins PTC0–PTC4 IPTC0–PTC4 ± 25 mA Maximum current into VDD IMVDD 150 mA Maximum current out of VSS IMVSS 150 mA Storage temperature Tstg –55 to +150 °C 1. Voltages referenced to V SS NOTE This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum-rated voltages to this high-impedance circuit. For proper operation, it is recommended that V and V be constrained to the range In Out V ≤ (V or V ) ≤ V . Reliability of operation is enhanced if unused SS In Out DD inputs are connected to an appropriate logic voltage level (for example, either V or V ). SS DD MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 287

Electrical Specifications 21.3 Functional Operating Range Characteristic Symbol Value Unit Operating temperature range TA –40 to +125 °C 5.0 ±10% Operating voltage range VDD 3.3 ±10% V 21.4 Thermal Characteristics Characteristic Symbol Value Unit Thermal resistance 32-pin LQFP θJA 95 °C/W 48-pin LQFP 95 I/O pin power dissipation PI/O User determined W P = (I × V ) + P = Power dissipation(1) PD D K/D(TD + 2D7D3 °C)I/O W J P × (T + 273 °C) D A Constant(2) K W/°C + P 2 × θ D JA Average junction temperature TJ TA + (PD × θJA) °C 1. Power dissipation is a function of temperature. 2. K is a constant unique to the device. K can be determined for a known T and measured P . With this value of K, P and A D D T can be determined for any value of T . J A MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 288 Freescale Semiconductor

5-Vdc Electrical Characteristics 21.5 5-Vdc Electrical Characteristics Characteristic(1) Symbol Min Typ(2) Max Unit Output high voltage (ILoad = –2.0 mA) all I/O pins VOH VDD – 0.8 — — V (ILoad = –10.0 mA) all I/O pins VOH VDD – 1.5 —— —— VV (ILoad = –20.0 mA) pins PTC0–PTC4 only VOH VDD – 1.5 Maximum combined IOH for port PTA7–PTA3, IOH1 — — 50 mA port PTC0–PTC1, port E, port PTD0–PTD3 Maximum combined IOH for port PTA2–PTA0, IOH2 — — 50 mA port B, port PTC2-PTC6, port PTD4–PTD7 Maximum total IOH for all port pins IOHT — — 100 mA Output low voltage (I = 1.6 mA) all I/O pins V — — 0.4 V Load OL (I = 10 mA) all I/O pins V — — 1.5 V Load OL — — 1.5 V (I = 20mA) pins PTC0–PTC4 only V Load OL Maximum combined I for port PTA7–PTA3, I OH OL1 — — 50 mA port PTC0-PTC1, port E, port PTD0–PTD3 Maximum combined I for port PTA2–PTA0, I OH OL2 — — 50 mA port B, port PTC2–PTC6, port PTD4–PTD7 Maximum total IOL for all port pins IOLT — — 100 mA Input high voltage All ports, IRQ, RST, OSC1 VIH 0.7 × VDD — VDD V Input low voltage All ports, IRQ, RST, OSC1 VIL VSS — 0.2 × VDD V V supply current DD Run(3) — 20 30 mA Wait(4) — 6 12 mA Stop(5) IDD — 0.6 10 μA Stop with TBM enabled(6) — 1 1.25 mA Stop with LVI and TBM enabled(6) — 1.25 1.6 mA Stop with LVI — 250 350 μA DC injection current(7) (8) (9) (10) Single pin limit Vin > VDD 0 — 2 V < V I 0 — –0.2 mA in SS IC Total MCU limit, includes sum of all stressed pins V > V 0 — 25 in DD V < V 0 — –5 in SS I/O ports Hi-Z leakage current(11) IIL 0 — ±10 μA Input current IIn 0 — ±1 μA Pullup resistors (as input only) Ports PTA7/KBD7–PTA0/KBD0, PTC6–PTC0/CANTX, RPU 20 45 65 kΩ PTD7/T2CH1–PTD0/SS Capacitance COut — — 12 pF Ports (as input or output) C — — 8 In Continued on next page MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 289

Electrical Specifications Characteristic(1) Symbol Min Typ(2) Max Unit Monitor mode entry voltage VTST VDD + 2.5 — VDD + 4.0 V Low-voltage inhibit, trip falling voltage VTRIPF 3.90 4.25 4.50 V Low-voltage inhibit, trip rising voltage VTRIPR 4.20 4.35 4.60 V Low-voltage inhibit reset/recover hysteresis (V + V = V ) VHYS — 100 — mV TRIPF HYS TRIPR POR rearm voltage(12) VPOR 0 — 100 mV POR reset voltage(13) VPORRST 0 700 800 mV POR rise time ramp rate(14) RPOR 0.035 — — V/ms 1. V = 5.0 Vdc ± 10%, V = 0 Vdc, T = T (min) to T (max), unless otherwise noted DD SS A A A 2. Typical values reflect average measurements at midpoint of voltage range, 25°C only. 3. Run (operating) I measured using external square wave clock source (f = 32 MHz). All inputs 0.2 V from rail. No dc DD OSC loads. Less than 100 pF on all outputs. C = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly L affects run I . Measured with all modules enabled. DD 4. Wait I measured using external square wave clock source (f = 32 MHz). All inputs 0.2 V from rail. No dc loads. Less DD OSC than 100 pF on all outputs. C = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects wait L I . Measured with CGM and LVI enabled. DD 5. Stop I is measured with OSC1 = V . All inputs 0.2 V from rail. No dc loads. Less than 100 pF on all outputs. All ports DD SS configured as inputs. Typical values at midpoint of voltage range, 25°C only. 6. Stop I with TBM enabled is measured using an external square wave clock source (f = 8 MHz). All inputs 0.2 V from DD OSC rail. No dc loads. Less than 100 pF on all outputs. All inputs configured as inputs. 7. This parameter is characterized and not tested on each device. 8. All functional non-supply pins are internally clamped to V and V . SS DD 9. Input must be current limited to the value specified. To determine the value of the required current-limiting resistor, calculate resistance values for positive and negative clamp voltages, then use the larger of the two values. 10. Power supply must maintain regulation within operating V range during instantaneous and operating maximum current DD conditions. If positive injection current (V > V ) is greater than I , the injection current may flow out of V and could in DD DD DD result in external power supply going out of regulation. Ensure external V load will shunt current greater than maximum DD injection current. This will be the greatest risk when the MCU is not consuming power. Examples are: if no system clock is present, or if clock rate is very low (which would reduce overall power consumption). 11. Pullups and pulldowns are disabled. Port B leakage is specified in 21.10 5.0-Volt ADC Characteristics. 12. Maximum is highest voltage that POR is guaranteed. 13. Maximum is highest voltage that POR is possible. 14. If minimum V is not reached before the internal POR reset is released, RST must be driven low externally until minimum DD V is reached. DD MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 290 Freescale Semiconductor

3.3-Vdc Electrical Characteristics 21.6 3.3-Vdc Electrical Characteristics Characteristic(1) Symbol Min Typ(2) Max Unit Output high voltage (ILoad = –0.6 mA) all I/O pins VOH VDD – 0.3 — — V (ILoad = –4.0 mA) all I/O pins VOH VDD – 1.0 —— —— VV (ILoad = –10.0 mA) pins PTC0–PTC4 only VOH VDD – 1.0 Maximum combined IOH for port PTA7–PTA3, IOH1 — — 30 mA port PTC0–PTC1, port E, port PTD0–PTD3 Maximum combined IOH for port PTA2–PTA0, IOH2 — — 30 mA port B, port PTC2–PTC6, port PTD4–PTD7 Maximum total IOH for all port pins IOHT — — 60 mA Output low voltage (I = 1.6 mA) all I/O pins V — — 0.3 V Load OL (I = 10 mA) all I/O pins V — — 1.0 V Load OL — — 0.8 V (I = 20 mA) pins PTC0–PTC4 only V Load OL Maximum combined I for port PTA7–PTA3, I OH OL1 — — 30 mA port PTC0–PTC1, port E, port PTD0–PTD3 Maximum combined I for port PTA2–PTA0, I OH OL2 — — 30 mA port B, port PTC2–PTC6, port PTD4–PTD7 Maximum total IOL for all port pins IOLT — — 60 mA Input high voltage All ports, IRQ, RST, OSC1 VIH 0.7 × VDD — VDD V Input low voltage All ports, IRQ, RST, OSC1 VIL VSS — 0.3 × VDD V V supply current DD Run(3) — 8 12 mA Wait(4) — 3 6 mA Stop(5) IDD — 0.5 6 μA Stop with TBM enabled(6) — 500 700 μA Stop with LVI and TBM enabled(6) — 700 900 μA Stop with LVI — 200 300 μA DC injection current(7) (8) (9) (10) Single pin limit Vin > VDD 0 — 2 V < V I 0 — –0.2 mA in SS IC Total MCU limit, includes sum of all stressed pins V > V 0 — 25 in DD V < V 0 — –5 in SS I/O ports Hi-Z leakage current(11) IIL 0 — ±10 μA Input current IIn 0 — ±1 μA Pullup resistors (as input only) Ports PTA7/KBD7–PTA0/KBD0, PTC6–PTC0, RPU 20 45 65 kΩ PTD7/T2CH1–PTD0/SS Capacitance COut — — 12 pF Ports (as input or output) C — — 8 In Continued on next page MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 291

Electrical Specifications Characteristic(1) Symbol Min Typ(2) Max Unit Monitor mode entry voltage VTST VDD + 2.5 — VDD + 4.0 V Low-voltage inhibit, trip falling voltage VTRIPF 2.35 2.6 2.7 V Low-voltage inhibit, trip rising voltage VTRIPR 2.4 2.66 2.8 V Low-voltage inhibit reset/recover hysteresis (V + V = V ) VHYS — 100 — mV TRIPF HYS TRIPR POR rearm voltage(12) VPOR 0 — 100 mV POR reset voltage(13) VPORRST 0 700 800 mV POR rise time ramp rate(14) RPOR 0.035 — — V/ms 1. V = 3.3 Vdc ± 10%, V = 0 Vdc, T = T (min) to T (max), unless otherwise noted DD SS A A A 2. Typical values reflect average measurements at midpoint of voltage range, 25°C only. 3. Run (operating) I measured using external square wave clock source (f = 16 MHz). All inputs 0.2 V from rail. No dc DD OSC loads. Less than 100 pF on all outputs. C = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly L affects run I . Measured with all modules enabled. DD 4. Wait I measured using external square wave clock source (f = 16 MHz). All inputs 0.2 V from rail. No dc loads. Less DD OSC than 100 pF on all outputs. C = 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects wait L I . Measured with CGM and LVI enabled. DD 5. Stop I is measured with OSC1 = V . All inputs 0.2 V from rail. No dc loads. Less than 100 pF on all outputs. All ports DD SS configured as inputs. Typical values at midpoint of voltage range, 25°C only. 6. Stop I with TBM enabled is measured using an external square wave clock source (f = 4 MHz). All inputs 0.2 V from DD OSC rail. No dc loads. Less than 100 pF on all outputs. All inputs configured as inputs. 7. This parameter is characterized and not tested on each device. 8. All functional non-supply pins are internally clamped to V and V . SS DD 9. Input must be current limited to the value specified. To determine the value of the required current-limiting resistor, calculate resistance values for positive and negative clamp voltages, then use the larger of the two values. 10. Power supply must maintain regulation within operating V range during instantaneous and operating maximum current DD conditions. If positive injection current (V > V ) is greater than I , the injection current may flow out of V and could in DD DD DD result in external power supply going out of regulation. Ensure external V load will shunt current greater than maximum DD injection current. This will be the greatest risk when the MCU is not consuming power. Examples are: if no system clock is present, or if clock rate is very low (which would reduce overall power consumption). 11. Pullups and pulldowns are disabled. 12. Maximum is highest voltage that POR is guaranteed. 13. Maximum is highest voltage that POR is possible. 14. If minimum V is not reached before the internal POR reset is released, RST must be driven low externally until DD minimum V is reached. DD MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 292 Freescale Semiconductor

5.0-Volt Control Timing 21.7 5.0-Volt Control Timing Characteristic(1) Symbol Min Max Unit Frequency of operation Crystal option fOSC 1 8 MHz External clock option(2) dc 32 Internal operating frequency fOP (fBus) — 8 MHz Internal clock period (1/fOP) tCYC 125 — ns RST input pulse width low tRL 50 — ns IRQ interrupt pulse width low (edge-triggered) tILIH 50 — ns IRQ interrupt pulse period tILIL Note(3) — tCYC 1. V = 0 Vdc; timing shown with respect to 20% V and 70% V unless otherwise noted. SS DD DD 2. No more than 10% duty cycle deviation from 50%. 3. The minimum period is the number of cycles it takes to execute the interrupt service routine plus 1 t . CYC 21.8 3.3-Volt Control Timing Characteristic(1) Symbol Min Max Unit Frequency of operation Crystal option fOSC 1 8 MHz External clock option(2) dc 16 Internal operating frequency fOP (fBus) — 4 MHz Internal clock period (1/fOP) tCYC 250 — ns RST input pulse width low tRL 125 — ns IRQ interrupt pulse width low (edge-triggered) tILIH 125 — ns IRQ interrupt pulse period tILIL Note(3) — tCYC 1. V = 0 Vdc; timing shown with respect to 20% V and 70% V unless otherwise noted. SS DD DD 2. No more than 10% duty cycle deviation from 50%. 3. The minimum period is the number of cycles it takes to execute the interrupt service routine plus 1 t . CYC t RL RST t ILIL t ILIH IRQ Figure 21-1. RST and IRQ Timing MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 293

Electrical Specifications 21.9 Clock Generation Module Characteristics 21.9.1 CGM Component Specifications Characteristic Symbol Min Typ Max Unit Crystal frequency fXCLK 1 4 8 MHz Crystal load capacitance(1) CL — — — pF Crystal fixed capacitance C1 — (2 x CL) –5 — pF Crystal tuning capacitance C2 — (2 x CL) –5 — pF Feedback bias resistor RB 1 10 20 MΩ 1. Consult crystal manufacturer’s data. 21.9.2 CGM Electrical Specifications Characteristic Symbol Min Typ Max Unit Reference frequency (for PLL operation) fRCLK 1 4 8 MHz Range nominal multiplier fNOM — 71.42 — KHz Programmed VCO center-of-range frequency(1) fVRS — (Lx2E)fNOM — MHz 1. See 4.3.6 Programming the PLL for detailed instruction on selecting appropriate values for L and E. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 294 Freescale Semiconductor

5.0-Volt ADC Characteristics 21.10 5.0-Volt ADC Characteristics Characteristic(1) Symbol Min Max Unit Comments V should be tied to DDAD Supply voltage VDDAD 4.5 5.5 V the same potential as VDD via separate traces. Input voltages VADIN 0 VDDAD V VADIN <= VDDAD Resolution BAD 10 10 Bits Absolute accuracy AAD –4 +4 LSB Includes quantization ADC internal clock fADIC 500 k 1.048 M Hz tAIC = 1/fADIC Conversion range RAD VSSAD VDDAD V Power-up time tADPU 16 — tAIC cycles Conversion time tADC 16 17 tAIC cycles Sample time tADS 5 — tAIC cycles Monotonicity MAD Guaranteed Zero input reading ZADI 000 003 Hex VADIN = VSSA Full-scale reading FADI 3FC 3FF Hex VADIN = VDDA Input capacitance CADI — 30 pF Not tested VDDAD/VREFH current IVREF — 1.6 mA Absolute accuracy (8-bit truncation mode) AAD –1 +1 LSB Includes quantization Quantization error — –1/8 +7/8 LSB (8-bit truncation mode) 1. V = 5.0 Vdc ± 10%, V = 0 Vdc, V = 5.0 Vdc ± 10%, V V = 0 Vdc DD SS DDAD/VREFH SSAD/ REFL MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 295

Electrical Specifications 21.11 3.3-Volt ADC Characteristics Characteristic(1) Symbol Min Max Unit Comments V should be tied to DDAD Supply voltage VDDAD 3.0 3.6 V the same potential as VDD via separate traces. Input voltages VADIN 0 VDDAD V VADIN <= VDDAD Resolution BAD 10 10 Bits Absolute accuracy AAD –6 +6 LSB Includes quantization ADC internal clock fADIC 500 k 1.048 M Hz tAIC = 1/fADIC Conversion range RAD VSSAD VDDAD V Power-up time tADPU 16 — tAIC cycles Conversion time tADC 16 17 tAIC cycles Sample time tADS 5 — tAIC cycles Monotonicity MAD Guaranteed Zero input reading ZADI 000 005 Hex VADIN = VSSA Full-scale reading FADI 3FA 3FF Hex VADIN = VDDA Input capacitance CADI — 30 pF Not tested VDDAD/VREFH current IVREF — 1.2 mA Absolute accuracy (8-bit truncation mode) AAD –1 +1 LSB Includes quantization Quantization error — –1/8 +7/8 LSB (8-bit truncation mode) 1. V = 3.3 Vdc ± 10%, V = 0 Vdc, V = 3.3 Vdc ± 10%, V V = 0 Vdc DD SS DDAD/VREFH SSAD/ REFL MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 296 Freescale Semiconductor

5.0-Volt SPI Characteristics 21.12 5.0-Volt SPI Characteristics Diagram Characteristic(2) Symbol Min Max Unit Number(1) Operating frequency Master fOP(M) fOP/128 fOP/2 MHz Slave fOP(S) dc fOP MHz Cycle time 1 Master tCYC(M) 2 128 tCYC Slave t 1 — t CYC(S) CYC 2 Enable lead time tLead(S) 1 — tCYC 3 Enable lag time tLag(S) 1 — tCYC Clock (SPSCK) high time 4 Master tSCKH(M) tCYC –25 64 tCYC ns Slave tSCKH(S) 1/2 tCYC –25 — ns Clock (SPSCK) low time 5 Master tSCKL(M) tCYC –25 64 tCYC ns Slave tSCKL(S) 1/2 tCYC –25 — ns Data setup time (inputs) 6 Master tSU(M) 30 — ns Slave t 30 — ns SU(S) Data hold time (inputs) 7 Master tH(M) 30 — ns Slave t 30 — ns H(S) Access time, slave(3) 8 CPHA = 0 tA(CP0) 0 40 ns CPHA = 1 tA(CP1) 0 40 ns 9 Disable time, slave(4) tDIS(S) — 40 ns Data valid time, after enable edge 10 Master tV(M) — 50 ns Slave(5) tV(S) — 50 ns Data hold time, outputs, after enable edge 11 Master tHO(M) 0 — ns Slave t 0 — ns HO(S) 1. Numbers refer to dimensions in Figure21-2 and Figure21-3. 2. All timing is shown with respect to 20% V and 70% V , unless noted; 100 pF load on all SPI pins. DD DD 3. Time to data active from high-impedance state 4. Hold time to high-impedance state 5. With 100 pF on all SPI pins MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 297

Electrical Specifications 21.13 3.3-Volt SPI Characteristics Diagram Characteristic(2) Symbol Min Max Unit Number(1) Operating frequency Master fOP(M) fOP/128 fOP/2 MHz Slave fOP(S) DC fOP MHz Cycle time 1 Master tCYC(M) 2 128 tcyc Slave t 1 — t CYC(S) cyc 2 Enable lead time tLead(S) 1 — tcyc 3 Enable lag time tLag(S) 1 — tcyc Clock (SPSCK) high time 4 Master tSCKH(M) tcyc –35 64 tcyc ns Slave tSCKH(S) 1/2 tcyc –35 — ns Clock (SPSCK) low time ± 5 Master tSCKL(M) tcyc –35 64 tcyc ns Slave tSCKL(S) 1/2 tcyc –35 — ns Data setup time (inputs) 6 Master tSU(M) 40 — ns Slave t 40 — ns SU(S) Data hold time (inputs) 7 Master tH(M) 40 — ns Slave t 40 — ns H(S) Access time, slave(3) 8 CPHA = 0 tA(CP0) 0 50 ns CPHA = 1 tA(CP1) 0 50 ns 9 Disable time, slave(4) tDIS(S) — 50 ns Data valid time, after enable edge 10 Master tV(M) — 60 ns Slave(5) tV(S) — 60 ns Data hold time, outputs, after enable edge 11 Master tHO(M) 0 — ns Slave t 0 — ns HO(S) 1. Numbers refer to dimensions in Figure21-2 and Figure21-3. 2. All timing is shown with respect to 20% V and 70% V , unless noted; 100 pF load on all SPI pins. DD DD 3. Time to data active from high-impedance state 4. Hold time to high-impedance state 5. With 100 pF on all SPI pins MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 298 Freescale Semiconductor

3.3-Volt SPI Characteristics SS INPUT SS PIN OF MASTER HELD HIGH 1 SPSCK OUTPUT 5 NOTE CPOL = 0 4 SPSCK OUTPUT 5 NOTE CPOL = 1 4 6 7 MISO MSB IN BITS 6–1 LSB IN INPUT 11 10 11 MOSI MASTER MSB OUT BITS 6–1 MASTER LSB OUT OUTPUT Note: This first clock edge is generated internally, but is not seen at the SPSCK pin. a) SPI Master Timing (CPHA = 0) SS INPUT SS PIN OF MASTER HELD HIGH 1 SPSCK OUTPUT 5 CPOL = 0 NOTE 4 SPSCK OUTPUT 5 CPOL = 1 NOTE 4 6 7 MISO INPUT MSB IN BITS 6–1 LSB IN 10 11 10 MOSI OUTPUT MASTER MSB OUT BITS 6–1 MASTER LSB OUT Note: This last clock edge is generated internally, but is not seen at the SPSCK pin. b) SPI Master Timing (CPHA = 1) Figure 21-2. SPI Master Timing MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 299

Electrical Specifications SS INPUT 1 3 SPSCK INPUT 55 CPOL = 0 4 2 SPSCK INPUT 5 CPOL = 1 4 8 9 MISO INPUT SLAVE MSB OUT BITS 6–1 SLAVE LSB OUT NOTE 6 7 10 11 11 MOSI OUTPUT MSB IN BITS 6–1 LSB IN Note: Not defined but normally MSB of character just received a) SPI Slave Timing (CPHA = 0) SS INPUT 1 SPSCK INPUT 5 CPOL = 0 4 2 3 SPSCK INPUT 5 CPOL = 1 4 8 10 9 MISO OUTPUT NOTE SLAVE MSB OUT BITS 6–1 SLAVE LSB OUT 6 7 10 11 MOSI INPUT MSB IN BITS 6–1 LSB IN Note: Not defined but normally LSB of character previously transmitted b) SPI Slave Timing (CPHA = 1) Figure 21-3. SPI Slave Timing MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 300 Freescale Semiconductor

Timer Interface Module Characteristics 21.14 Timer Interface Module Characteristics Characteristic Symbol Min Max Unit Timer input capture pulse width tTH, tTL 2 — tCYC Timer Input capture period tTLTL Note(1) — tCYC 1. The minimum period is the number of cycles it takes to execute the interrupt service routine plus 1 t . CYC t TLTL t TH INPUT CAPTURE RISING EDGE t TLTL t TL INPUT CAPTURE FALLING EDGE t TLTL tTH tTL INPUT CAPTURE BOTH EDGES Figure 21-4. Input Capture Timing MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 301

Electrical Specifications 21.15 Memory Characteristics Characteristic Symbol Min Typ Max Unit RAM data retention voltage VRDR 1.3 — — V FLASH program bus clock frequency — 1 — — MHz FLASH read bus clock frequency f (1) 0 — 8 M Hz Read FLASH page erase time Limited endurance (<1 K cycles) t (2) 0.9 1 1.1 ms Erase Maximum endurance (>1 K cycles) 3.6 4 5.5 FLASH mass erase time t (3) 4 — — ms MErase FLASH PGM/ERASE to HVEN setup time tNVS 10 — — μs FLASH high-voltage hold time tNVH 5 — — μs FLASH high-voltage hold time (mass erase) tNVHL 100 — — μs FLASH program hold time tPGS 5 — — μs FLASH program time tPROG 30 — 40 μs FLASH return to read time t (4) 1 — — μs RCV FLASH cumulative program hv period t (5) — — 4 ms HV FLASH endurance(6) — 10 k 100 k — Cycles FLASH data retention time(7) — 15 100 — Years 1. f is defined as the frequency range for which the FLASH memory can be read. Read 2. If the page erase time is longer than t (min), there is no erase disturb, but it reduces the endurance of the FLASH Erase memory. 3. If the mass erase time is longer than t (min), there is no erase disturb, but it reduces the endurance of the FLASH MErase memory. 4. t is defined as the time it needs before the FLASH can be read after turning off the high voltage charge pump, by RCV clearing HVEN to 0. 5. t is defined as the cumulative high voltage programming time to the same row before next erase. HV t must satisfy this condition: t + t + t + (t x 32) ≤ t maximum. HV NVS NVH PGS PROG HV 6. Typical endurance was evaluated for this product family. For additional information on how Freescale Semiconductor defines Typical Endurance, please refer to Engineering Bulletin EB619. 7. Typical data retention values are based on intrinsic capability of the technology measured at high temperature and de-rated to 25°C using the Arrhenius equation. For additional information on how Freescale Semiconductor defines Typical Data Retention, please refer to Engineering Bulletin EB618. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 302 Freescale Semiconductor

Chapter 22 Ordering Information and Mechanical Specifications 22.1 Introduction This section provides ordering information for the MC68HC908GZ16 along with the dimensions for: (cid:129) 32-pin low-profile quad flat pack package (case 873A) (cid:129) 48-pin low-profile quad flat pack (case 932-03) The following figures show the latest package drawings at the time of this publication. To make sure that you have the latest package specifications, contact your local Freescale Semiconductor Sales Office. 22.2 MC Order Numbers Table 22-1. MC Order Numbers Operating MC Order Number Package Temperature Range MC908GZ16CFJ –40°C to +85°C 32-pin low-profile MC908GZ16VFJ –40°C to +105°C quad flat package (LQFP) MC908GZ16MFJ –40°C to +125°C MC908GZ16CFA –40°C to +85°C 48-pin low-profile MC908GZ16VFA –40°C to +105°C quad flat package (LQFP) MC908GZ16MFA –40°C to +125°C Temperature designators: C = –40°C to +85°C V = –40°C to +105°C M = –40°C to +125°C M C 9 0 8 G Z 1 6 X XX E Pb FREE FAMILY PACKAGE DESIGNATOR TEMPERATURE RANGE Figure 22-1. Device Numbering System 22.3 Package Dimensions Refer to the following pages for detailed package dimensions. MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 303

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Appendix A MC68HC908GZ8 A.1 Introduction The MC68HC908GZ8 is a member of the low-cost, high-performance M68HC08 Family of 8-bit microcontroller units (MCUs). All MCUs in the family use the enhanced M68HC08 central processor unit (CPU08) and are available with a variety of modules, memory sizes and types, and package types. The information contained in this document pertains to the MC68HC908GZ8 with the exceptions shown in this appendix. A.2 Block Diagram See Figure A-1. A.3 Memory The MC68HC908GZ8 can address 8 Kbytes of memory space. The memory map, shown in Figure A-2, includes: (cid:129) 8 Kbytes of user FLASH memory (cid:129) 1024 bytes of random-access memory (RAM) (cid:129) 406 bytes of FLASH programming routines read-only memory (ROM) (cid:129) 44 bytes of user-defined vectors (cid:129) 350 bytes of monitor ROM MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 311

INTERNAL BUS M68HC08 CPU REGCISPTUERS ARITUHNMIET T(AICL/ULO)GIC PROGRAMMMOADBULLEE TIMEBASE DDRA PORTA PPTTAA70//KKBBDD70–(1) PTB7/AD7 SINGLE BREAKPOINT CONTROL AND STATUS REGISTERS — 64 BYTES PTB6/AD6 BREAK MODULE PTB5/AD5 USER FLASH — 7936 BYTES LOWD-UVAOLL TVAOGLETA INGHEIBIT DDRB PORTB PPTTBB43//AADD43 MODULE PTB2/AD2 USER RAM — 1024 BYTES PTB1/AD1 8-BIT KEYBOARD PTB0/AD0 MONITOR ROM — 350 BYTES INTERRUPT MODULE PTC6(1) PTC5(1) FLASH PROGRAMMING ROUTINES ROM — 406 BYTES 2-CHANNEL TIMER USER FLASH VECTOR SPACE — 44 BYTES INTERFACE MODULE 1 DDRC PORTC PPPTTTCCC432(((111))),,, (((222))) 2-CHANNEL TIMER INTERFACE MODULE 2 PTC1/CANRX(1), (2) CLOCK GENERATOR MODULE PTC0/CAN (1), (2) TX OSC1 1–8 MHz OSCILLATOR ENHANCED SERIAL OSC2 COMUNICATIONS PTD7/T2CH1(1) PHASE LOCKED LOOP INTERFACE MODULE PTD6/T2CH0(1) CGMXFC PTD5/T1CH1(1) RST(3) SYSTEM INTEGRATION COPMROPUPTEERRL YO MPEORDAUTLIENG DDRD PORTD PPPTTTDDD234///MST1POCSSHCI(0K1()(11)) MODULE SERIAL PERIPHERAL PTD1/MISO(1) INTERFACE MODULE PTD0/SS(1) IRQ(3) SINGLE EXTERNAL INTERRUPT MODULE PTE5–PTE2 VVDDAD//VVREFH 10-CBOITN AVNEARLTOEGR- TMOO-DDUIGLIETAL MONITOR MODULE DDRE PORTE PPTTEE10//RTxxDD DDAD REFL MEMORY MAP MODULE POWER-ON RESET MODULE SECURITY CONFIGURATION MODULE VDD REGISTER 1–2 VSS POWER MODULE V DDA V MONITOR MODE ENTRY SSA MSCAN08 MODULE MODULE 1. Ports are software configurable with pullup device if input port. 2. Higher current drive port pins 3. Pin contains integrated pullup device Figure A-1. MC68HC908GZ8 Block Diagram MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 312 Freescale Semiconductor

$0000 $FE03 SIM BREAK FLAG CONTROL REGISTER (SBFCR) I/O REGISTERS ↓ $FE04 INTERRUPT STATUS REGISTER 1 (INT1) 64 BYTES $003F $FE05 INTERRUPT STATUS REGISTER 2 (INT2) $0040 $FE06 INTERRUPT STATUS REGISTER 3 (INT3) RAM ↓ $FE07 RESERVED 1024 BYTES $043F $FE08 FLASH CONTROL REGISTER (FLCR) $0440 $FE09 BREAK ADDRESS REGISTER HIGH (BRKH) UNIMPLEMENTED ↓ $FE0A BREAK ADDRESS REGISTER LOW (BRKL) 192 BYTES $04FF $FE0B BREAK STATUS AND CONTROL REGISTER (BRKSCR) $0500 $FE0C LVI STATUS REGISTER (LVISR) MSCAN08 CONTROL AND MESSAGE BUFFER ↓ $FE0D 128 BYTES UNIMPLEMENTED $057F ↓ 3 BYTES $0580 $FE0F UNIMPLEMENTED ↓ $FE10 UNIMPLEMENTED 5760 BYTES 16 BYTES $1BFF ↓ RESERVED FOR COMPATIBILITY WITH MONITOR CODE $1C00 $FE1F FOR A-FAMILY PART FLASH PROGRAMMING ROUTINES ROM ↓ $FE20 406 BYTES MONITOR ROM $1D95 ↓ 350 BYTES $1D96 $FF7D UNIMPLEMENTED ↓ $FF7E FLASH BLOCK PROTECT REGISTER (FLBPR) 49,770 BYTES $DFFF $FF7F UNIMPLEMENTED $E000 ↓ 85 BYTES FLASH MEMORY ↓ $FFD3 7680 BYTES $FDFF $FFD4 FLASH VECTORS $FE00 SIM BREAK STATUS REGISTER (SBSR) ↓ 44 BYTES $FE01 SIM RESET STATUS REGISTER (SRSR) $FFFF(1) $FE02 RESERVED 1. $FFF6–$FFFD used for eight security bytes Figure A-2. Memory Map MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 Freescale Semiconductor 313

A.4 Ordering Information Table A-1. MC Order Numbers MC Order Operating Package Number Temperature Range MC908GZ8CFJ –40°C to +85°C 32-pin low-profile MC908GZ8VFJ –40°C to +105°C quad flat pack (LQFP) MC908GZ8MFJ –40°C to +125°C MC908GZ8CFA –40°C to +85°C 48-pin low-profile MC908GZ8VFA –40°C to +105°C quad flat pack (LQFP) MC908GZ8MFA –40°C to +125°C Temperature designators: C = –40°C to +85°C V = –40°C to +105°C M = –40°C to +125°C M C 9 0 8 G Z 8 X XX E FAMILY Pb FREE PACKAGE DESIGNATOR TEMPERATURE RANGE Figure A-3. Device Numbering System MC68HC908GZ16 (cid:129) MC68HC908GZ8 Data Sheet, Rev. 4 314 Freescale Semiconductor

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