C8051F50x/F51x Mixed Signal ISP Flash MCU Family Analog Peripherals Memory - 12-Bit ADC - 4352 bytes internal data RAM (256 + 4096 XRAM) • Up to 200 ksps - 64 or 32 kB Flash; In-system programmable in • Up to 32 external single-ended inputs 512-byte Sectors • VREF from on-chip VREF, external pin or VDD • Internal or external start of conversion source Digital Peripherals • Built-in temperature sensor - 40, 33, or 25 Port I/O; All 5 V tolerant - Two Comparators - CAN 2.0 Controller—no crystal required • Programmable hysteresis and response time • Configurable as interrupt or reset source - LIN 2.1 Controller (Master and Slave capable); no • Low current crystal required On-Chip Debug - Hardware enhanced UART, SMBus™, and - On-chip debug circuitry facilitates full speed, non- enhanced SPI™ serial ports intrusive in-system debug (no emulator required) - Four general purpose 16-bit counter/timers - Provides breakpoints, single stepping, - 16-Bit programmable counter array (PCA) with six inspect/modify memory and registers capture/compare modules and enhanced PWM - Superior performance to emulation systems using functionality ICE-chips, target pods, and sockets Clock Sources - Low cost, complete development kit - Internal 24 MHz with ±0.5% accuracy for CAN and Supply Voltage 1.8 to 5.25 V master LIN operation - Typical operating current: 19 mA at 50 MHz; - External oscillator: Crystal, RC, C, or clock - Typical stop mode current:2 µA (1 or 2 pin modes) High-Speed 8051 µC Core - Can switch between clock sources on-the-fly; - Pipelined instruction architecture; executes 70% of useful in power saving modes instructions in 1 or 2 system clocks Packages - Up to 50 MIPS throughput with 50 MHz clock - 48-Pin QFP/QFN (C8051F500/1/4/5) - Expanded interrupt handler - 40-Pin QFN (C8051F508/9-F510/1) - 32-Pin QFP/QFN (C8051F502/3/6/7) Automotive Qualified - Temperature Range: –40 to +125 °C - Compliant to AEC-Q100 ANALOG DIGITAL I/O PERIPHERALS A 12-bit UART 0 Ports 0-4 M TEMP SMBus Crossbar 200 ksps U SENSOR SPI External ADC X PCA Memory Timers 0-3 Interface CAN Voltage VREG LIN Comparators 0-1 VREF 24 MHz PRECISION 2x Clock Multiplier INTERNAL OSCILLATOR HIGH-SPEED CONTROLLER CORE 64 kB 8051 CPU 4 kB XRAM ISP FLASH (50 MIPS) FLEXIBLE DEBUG POR WDT INTERRUPTS CIRCUITRY Rev. 1.2 3/11 Copyright © 2011 by Silicon Laboratories C8051F500/1/2/3/4/5/6/7/8/9-F510/1

C8051F50x/F51x 2 Rev. 1.2

C8051F50x/F51x Table of Contents 1. System Overview..................................................................................................... 16 2. Ordering Information............................................................................................... 20 3. Pin Definitions.......................................................................................................... 22 4. Package Specifications........................................................................................... 30 4.1. QFP-48 Package Specifications........................................................................ 30 4.2. QFN-48 Package Specifications........................................................................ 32 4.3. QFN-40 Package Specifications........................................................................ 34 4.4. QFP-32 Package Specifications........................................................................ 36 4.5. QFN-32 Package Specifications........................................................................ 38 5. Electrical Characteristics........................................................................................ 40 5.1. Absolute Maximum Specifications..................................................................... 40 5.2. Electrical Characteristics................................................................................... 41 6. 12-Bit ADC (ADC0)................................................................................................... 52 6.1. Modes of Operation........................................................................................... 53 6.1.1. Starting a Conversion................................................................................ 53 6.1.2. Tracking Modes......................................................................................... 53 6.1.3. Timing....................................................................................................... 54 6.1.4. Burst Mode................................................................................................ 55 6.2. Output Code Formatting.................................................................................... 57 6.2.1. Settling Time Requirements...................................................................... 57 6.3. Selectable Gain................................................................................................. 58 6.3.1. Calculating the Gain Value........................................................................ 58 6.3.2. Setting the Gain Value.............................................................................. 60 6.4. Programmable Window Detector....................................................................... 66 6.4.1. Window Detector In Single-Ended Mode.................................................. 68 6.5. ADC0 Analog Multiplexer.................................................................................. 70 7. Temperature Sensor................................................................................................ 72 8. Voltage Reference.................................................................................................... 73 9. Comparators............................................................................................................. 75 9.1. Comparator Multiplexer..................................................................................... 81 10. Voltage Regulator (REG0)..................................................................................... 84 11. CIP-51 Microcontroller........................................................................................... 86 11.1. Performance.................................................................................................... 86 11.2. Instruction Set.................................................................................................. 88 11.2.1. Instruction and CPU Timing.................................................................... 88 11.3. CIP-51 Register Descriptions.......................................................................... 92 11.4. Serial Number Special Function Registers (SFRs)......................................... 96 12. Memory Organization............................................................................................ 97 12.1. Program Memory............................................................................................. 98 12.1.1. MOVX Instruction and Program Memory................................................ 98 12.2. Data Memory................................................................................................... 98 12.2.1. Internal RAM........................................................................................... 98 12.2.1.1. General Purpose Registers............................................................ 99 12.2.1.2. Bit Addressable Locations.............................................................. 99 Rev. 1.2 3

C8051F50x/F51x 12.2.1.3. Stack ............................................................................................ 99 13. Special Function Registers................................................................................. 100 13.1. SFR Paging................................................................................................... 100 13.2. Interrupts and SFR Paging............................................................................ 100 13.3. SFR Page Stack Example............................................................................. 101 14. Interrupts.............................................................................................................. 117 14.1. MCU Interrupt Sources and Vectors.............................................................. 117 14.1.1. Interrupt Priorities.................................................................................. 118 14.1.2. Interrupt Latency................................................................................... 118 14.2. Interrupt Register Descriptions...................................................................... 120 14.3. External Interrupts INT0 and INT1................................................................. 126 15. Flash Memory....................................................................................................... 129 15.1. Programming the Flash Memory................................................................... 129 15.1.1. Flash Lock and Key Functions.............................................................. 129 15.1.2. Flash Erase Procedure......................................................................... 129 15.1.3. Flash Write Procedure.......................................................................... 130 15.1.4. Flash Write Optimization....................................................................... 130 15.2. Non-volatile Data Storage............................................................................. 131 15.3. Security Options............................................................................................ 131 15.4. Flash Write and Erase Guidelines................................................................. 133 15.4.1. V Maintenance and the V monitor ................................................ 133 DD DD 15.4.2. PSWE Maintenance.............................................................................. 133 15.4.3. System Clock........................................................................................ 134 16. Power Management Modes................................................................................. 138 16.1. Idle Mode....................................................................................................... 138 16.2. Stop Mode..................................................................................................... 139 16.3. Suspend Mode.............................................................................................. 139 17. Reset Sources...................................................................................................... 141 17.1. Power-On Reset............................................................................................ 142 17.2. Power-Fail Reset/VDD Monitor..................................................................... 142 17.3. External Reset............................................................................................... 144 17.4. Missing Clock Detector Reset....................................................................... 144 17.5. Comparator0 Reset....................................................................................... 145 17.6. PCA Watchdog Timer Reset......................................................................... 145 17.7. Flash Error Reset.......................................................................................... 145 17.8. Software Reset.............................................................................................. 145 18. External Data Memory Interface and On-Chip XRAM....................................... 147 18.1. Accessing XRAM........................................................................................... 147 18.1.1. 16-Bit MOVX Example.......................................................................... 147 18.1.2. 8-Bit MOVX Example............................................................................ 147 18.2. Configuring the External Memory Interface................................................... 148 18.3. Port Configuration.......................................................................................... 148 18.4. Multiplexed and Non-multiplexed Selection................................................... 153 18.4.1. Multiplexed Configuration...................................................................... 153 18.4.2. Non-multiplexed Configuration.............................................................. 154 4 Rev. 1.2

C8051F50x/F51x 18.5. Memory Mode Selection................................................................................ 155 18.5.1. Internal XRAM Only.............................................................................. 155 18.5.2. Split Mode without Bank Select............................................................. 155 18.5.3. Split Mode with Bank Select.................................................................. 156 18.5.4. External Only......................................................................................... 156 18.6. Timing .......................................................................................................... 156 18.6.1. Non-Multiplexed Mode.......................................................................... 158 18.6.1.1. 16-bit MOVX: EMI0CF[4:2] = 101, 110, or 111............................. 158 18.6.1.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = 101 or 111....... 159 18.6.1.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = 110....................... 160 18.6.2. Multiplexed Mode.................................................................................. 161 18.6.2.1. 16-bit MOVX: EMI0CF[4:2] = 001, 010, or 011............................. 161 18.6.2.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = 001 or 011....... 162 18.6.2.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = 010....................... 163 19. Oscillators and Clock Selection......................................................................... 165 19.1. System Clock Selection................................................................................. 165 19.2. Programmable Internal Oscillator.................................................................. 167 19.2.1. Internal Oscillator Suspend Mode......................................................... 167 19.3. Clock Multiplier.............................................................................................. 170 19.4. External Oscillator Drive Circuit..................................................................... 172 19.4.1. External Crystal Example...................................................................... 174 19.4.2. External RC Example............................................................................ 175 19.4.3. External Capacitor Example.................................................................. 175 20. Port Input/Output................................................................................................. 177 20.1. Port I/O Modes of Operation.......................................................................... 178 20.1.1. Port Pins Configured for Analog I/O...................................................... 178 20.1.2. Port Pins Configured For Digital I/O...................................................... 178 20.1.3. Interfacing Port I/O in a Multi-Voltage System...................................... 179 20.2. Assigning Port I/O Pins to Analog and Digital Functions............................... 179 20.2.1. Assigning Port I/O Pins to Analog Functions........................................ 179 20.2.2. Assigning Port I/O Pins to Digital Functions.......................................... 179 20.2.3. Assigning Port I/O Pins to External Digital Event Capture Functions... 180 20.3. Priority Crossbar Decoder............................................................................. 180 20.4. Port I/O Initialization...................................................................................... 182 20.5. Port Match..................................................................................................... 187 20.6. Special Function Registers for Accessing and Configuring Port I/O............. 191 21. Local Interconnect Network (LIN)....................................................................... 201 21.1. Software Interface with the LIN Controller..................................................... 202 21.2. LIN Interface Setup and Operation................................................................ 202 21.2.1. Mode Definition..................................................................................... 202 21.2.2. Baud Rate Options: Manual or Autobaud............................................. 202 21.2.3. Baud Rate Calculations: Manual Mode................................................. 202 21.2.4. Baud Rate Calculations—Automatic Mode........................................... 204 21.3. LIN Master Mode Operation.......................................................................... 205 21.4. LIN Slave Mode Operation............................................................................ 206 Rev. 1.2 5

C8051F50x/F51x 21.5. Sleep Mode and Wake-Up............................................................................ 207 21.6. Error Detection and Handling........................................................................ 207 21.7. LIN Registers................................................................................................. 208 21.7.1. LIN Direct Access SFR Registers Definitions....................................... 208 21.7.2. LIN Indirect Access SFR Registers Definitions..................................... 210 22. Controller Area Network (CAN0)........................................................................ 218 22.1. Bosch CAN Controller Operation................................................................... 219 22.1.1. CAN Controller Timing.......................................................................... 219 22.1.2. CAN Register Access............................................................................ 220 22.1.3. Example Timing Calculation for 1 Mbit/Sec Communication................ 220 22.2. CAN Registers............................................................................................... 222 22.2.1. CAN Controller Protocol Registers........................................................ 222 22.2.2. Message Object Interface Registers..................................................... 222 22.2.3. Message Handler Registers.................................................................. 222 22.2.4. CAN Register Assignment.................................................................... 223 23. SMBus................................................................................................................... 226 23.1. Supporting Documents.................................................................................. 227 23.2. SMBus Configuration..................................................................................... 227 23.3. SMBus Operation.......................................................................................... 227 23.3.1. Transmitter vs. Receiver....................................................................... 228 23.3.2. Arbitration.............................................................................................. 228 23.3.3. Clock Low Extension............................................................................. 228 23.3.4. SCL Low Timeout.................................................................................. 228 23.3.5. SCL High (SMBus Free) Timeout......................................................... 229 23.4. Using the SMBus........................................................................................... 229 23.4.1. SMBus Configuration Register.............................................................. 229 23.4.2. SMB0CN Control Register.................................................................... 233 23.4.3. Data Register........................................................................................ 236 23.5. SMBus Transfer Modes................................................................................. 236 23.5.1. Write Sequence (Master)...................................................................... 237 23.5.2. Read Sequence (Master)...................................................................... 238 23.5.3. Write Sequence (Slave)........................................................................ 239 23.5.4. Read Sequence (Slave)........................................................................ 240 23.6. SMBus Status Decoding................................................................................ 240 24. UART0................................................................................................................... 243 24.1. Baud Rate Generator.................................................................................... 243 24.2. Data Format................................................................................................... 245 24.3. Configuration and Operation......................................................................... 246 24.3.1. Data Transmission................................................................................ 246 24.3.2. Data Reception..................................................................................... 246 24.3.3. Multiprocessor Communications........................................................... 247 25. Enhanced Serial Peripheral Interface (SPI0)..................................................... 252 25.1. Signal Descriptions........................................................................................ 253 25.1.1. Master Out, Slave In (MOSI)................................................................. 253 25.1.2. Master In, Slave Out (MISO)................................................................. 253 6 Rev. 1.2

C8051F50x/F51x 25.1.3. Serial Clock (SCK)................................................................................ 253 25.1.4. Slave Select (NSS)............................................................................... 253 25.2. SPI0 Master Mode Operation........................................................................ 254 25.3. SPI0 Slave Mode Operation.......................................................................... 256 25.4. SPI0 Interrupt Sources.................................................................................. 256 25.5. Serial Clock Phase and Polarity.................................................................... 257 25.6. SPI Special Function Registers..................................................................... 258 26. Timers................................................................................................................... 265 26.1. Timer 0 and Timer 1...................................................................................... 267 26.1.1. Mode 0: 13-bit Counter/Timer............................................................... 267 26.1.2. Mode 1: 16-bit Counter/Timer............................................................... 268 26.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload..................................... 268 26.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................ 269 26.2. Timer 2.......................................................................................................... 275 26.2.1. 16-bit Timer with Auto-Reload............................................................... 275 26.2.2. 8-bit Timers with Auto-Reload............................................................... 275 26.2.3. External Oscillator Capture Mode......................................................... 276 26.3. Timer 3.......................................................................................................... 281 26.3.1. 16-bit Timer with Auto-Reload............................................................... 281 26.3.2. 8-bit Timers with Auto-Reload............................................................... 281 26.3.3. External Oscillator Capture Mode......................................................... 282 27. Programmable Counter Array............................................................................. 287 27.1. PCA Counter/Timer....................................................................................... 288 27.2. PCA0 Interrupt Sources................................................................................. 289 27.3. Capture/Compare Modules........................................................................... 289 27.3.1. Edge-triggered Capture Mode............................................................... 290 27.3.2. Software Timer (Compare) Mode.......................................................... 291 27.3.3. High-Speed Output Mode..................................................................... 292 27.3.4. Frequency Output Mode....................................................................... 293 27.3.5. 8-bit, 9-bit, 10-bit and 11-bit Pulse Width Modulator Modes................. 294 27.3.5.1. 8-bit Pulse Width Modulator Mode................................................ 294 27.3.5.2. 9/10/11-bit Pulse Width Modulator Mode...................................... 295 27.3.6. 16-Bit Pulse Width Modulator Mode...................................................... 296 27.4. Watchdog Timer Mode.................................................................................. 297 27.4.1. Watchdog Timer Operation................................................................... 297 27.4.2. Watchdog Timer Usage........................................................................ 298 27.5. Register Descriptions for PCA0..................................................................... 300 28. C2 Interface.......................................................................................................... 306 28.1. C2 Interface Registers................................................................................... 306 28.2. C2 Pin Sharing.............................................................................................. 309 Document Change List.............................................................................................. 310 Contact Information................................................................................................... 312 Rev. 1.2 7

C8051F50x/F51x List of Figures Figure 1.1. C8051F500/1/4/5 Block Diagram .......................................................... 17 Figure 1.2. C8051F508/9-F510/1 Block Diagram .................................................... 18 Figure 1.3. C8051F502/3/6/7 Block Diagram .......................................................... 19 Figure 3.1. QFP-48 Pinout Diagram (Top View) ...................................................... 25 Figure 3.2. QFN-48 Pinout Diagram (Top View) ..................................................... 26 Figure 3.3. QFN-40 Pinout Diagram (Top View) ..................................................... 27 Figure 3.4. QFP-32 Pinout Diagram (Top View) ...................................................... 28 Figure 3.5. QFN-32 Pinout Diagram (Top View) ..................................................... 29 Figure 4.1. QFP-48 Package Drawing ..................................................................... 30 Figure 4.2. QFP-48 Landing Diagram ..................................................................... 31 Figure 4.3. QFN-48 Package Drawing .................................................................... 32 Figure 4.4. QFN-48 Landing Diagram ..................................................................... 33 Figure 4.5. Typical QFN-40 Package Drawing ........................................................ 34 Figure 4.6. QFN-40 Landing Diagram ..................................................................... 35 Figure 4.7. QFP-32 Package Drawing ..................................................................... 36 Figure 4.8. QFP-32 Package Drawing ..................................................................... 37 Figure 4.9. QFN-32 Package Drawing .................................................................... 38 Figure 4.10. QFN-32 Package Drawing .................................................................. 39 Figure 5.1. Minimum VDD Monitor Threshold vs. System Clock Frequency ........... 44 Figure 6.1. ADC0 Functional Block Diagram ........................................................... 52 Figure 6.2. ADC0 Tracking Modes .......................................................................... 54 Figure 6.3. 12-Bit ADC Tracking Mode Example ..................................................... 55 Figure 6.4. 12-Bit ADC Burst Mode Example With Repeat Count Set to 4 ............. 56 Figure 6.5. ADC0 Equivalent Input Circuit ............................................................... 58 Figure 6.6. ADC Window Compare Example: Right-Justified Data ......................... 69 Figure 6.7. ADC Window Compare Example: Left-Justified Data ........................... 69 Figure 6.8. ADC0 Multiplexer Block Diagram .......................................................... 70 Figure 7.1. Temperature Sensor Transfer Function ................................................ 72 Figure 8.1. Voltage Reference Functional Block Diagram ....................................... 73 Figure 9.1. Comparator Functional Block Diagram ................................................. 75 Figure 9.2. Comparator Hysteresis Plot .................................................................. 76 Figure 9.3. Comparator Input Multiplexer Block Diagram ........................................ 81 Figure 10.1. External Capacitors for Voltage Regulator Input/Output— Regulator Enabled .............................................................................. 84 Figure 10.2. External Capacitors for Voltage Regulator Input/Output— Regulator Disabled ............................................................................. 85 Figure 11.1. CIP-51 Block Diagram ......................................................................... 87 Figure 12.1. C8051F50x-F51x Memory Map ........................................................... 97 Figure 12.2. Flash Program Memory Map ............................................................... 98 Figure 13.1. SFR Page Stack ................................................................................ 101 Figure 13.2. SFR Page Stack While Using SFR Page 0x0 To Access SPI0DAT . 102 Figure 13.3. SFR Page Stack After CAN0 Interrupt Occurs .................................. 103 Figure 13.4. SFR Page Stack Upon PCA Interrupt Occurring During a CAN0 ISR 104 Rev. 1.2 8

C8051F50x/F51x Figure 13.5. SFR Page Stack Upon Return From PCA Interrupt .......................... 105 Figure 13.6. SFR Page Stack Upon Return From CAN0 Interrupt ........................ 106 Figure 15.1. Flash Program Memory Map ............................................................. 131 Figure 17.1. Reset Sources ................................................................................... 141 Figure 17.2. Power-On and VDD Monitor Reset Timing ....................................... 142 Figure 18.1. Multiplexed Configuration Example ................................................... 153 Figure 18.2. Non-multiplexed Configuration Example ........................................... 154 Figure 18.3. EMIF Operating Modes ..................................................................... 155 Figure 18.4. Non-multiplexed 16-bit MOVX Timing ............................................... 158 Figure 18.5. Non-multiplexed 8-bit MOVX without Bank Select Timing ................ 159 Figure 18.6. Non-multiplexed 8-bit MOVX with Bank Select Timing ..................... 160 Figure 18.7. Multiplexed 16-bit MOVX Timing ....................................................... 161 Figure 18.8. Multiplexed 8-bit MOVX without Bank Select Timing ........................ 162 Figure 18.9. Multiplexed 8-bit MOVX with Bank Select Timing ............................. 163 Figure 19.1. Oscillator Options .............................................................................. 165 Figure 19.2. Example Clock Multiplier Output ....................................................... 170 Figure 19.3. External 32.768 kHz Quartz Crystal Oscillator Connection Diagram 175 Figure 20.1. Port I/O Functional Block Diagram .................................................... 177 Figure 20.2. Port I/O Cell Block Diagram .............................................................. 178 Figure 20.3. Peripheral Availability on Port I/O Pins .............................................. 181 Figure 20.4. Crossbar Priority Decoder in Example Configuration ........................ 182 Figure 21.1. LIN Block Diagram ............................................................................ 201 Figure 22.1. Typical CAN Bus Configuration ......................................................... 218 Figure 22.2. CAN Controller Diagram .................................................................... 219 Figure 22.3. Four segments of a CAN Bit .............................................................. 221 Figure 23.1. SMBus Block Diagram ...................................................................... 226 Figure 23.2. Typical SMBus Configuration ............................................................ 227 Figure 23.3. SMBus Transaction ........................................................................... 228 Figure 23.4. Typical SMBus SCL Generation ........................................................ 230 Figure 23.5. Typical Master Write Sequence ........................................................ 237 Figure 23.6. Typical Master Read Sequence ........................................................ 238 Figure 23.7. Typical Slave Write Sequence .......................................................... 239 Figure 23.8. Typical Slave Read Sequence .......................................................... 240 Figure 24.1. UART0 Block Diagram ...................................................................... 243 Figure 24.2. UART0 Timing Without Parity or Extra Bit ......................................... 245 Figure 24.3. UART0 Timing With Parity ................................................................ 245 Figure 24.4. UART0 Timing With Extra Bit ............................................................ 245 Figure 24.5. Typical UART Interconnect Diagram ................................................. 246 Figure 24.6. UART Multi-Processor Mode Interconnect Diagram ......................... 247 Figure 25.1. SPI Block Diagram ............................................................................ 252 Figure 25.2. Multiple-Master Mode Connection Diagram ...................................... 255 Figure 25.3. 3-Wire Single Master and 3-Wire Single Slave Mode Connection Diagram ......................................................................... 255 Figure 25.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection Diagram ......................................................................... 255 9 Rev. 1.2

C8051F50x/F51x Figure 25.5. Master Mode Data/Clock Timing ....................................................... 257 Figure 25.6. Slave Mode Data/Clock Timing (CKPHA = 0) ................................... 258 Figure 25.7. Slave Mode Data/Clock Timing (CKPHA = 1) ................................... 258 Figure 25.8. SPI Master Timing (CKPHA = 0) ....................................................... 262 Figure 25.9. SPI Master Timing (CKPHA = 1) ....................................................... 262 Figure 25.10. SPI Slave Timing (CKPHA = 0) ....................................................... 263 Figure 25.11. SPI Slave Timing (CKPHA = 1) ....................................................... 263 Figure 26.1. T0 Mode 0 Block Diagram ................................................................. 268 Figure 26.2. T0 Mode 2 Block Diagram ................................................................. 269 Figure 26.3. T0 Mode 3 Block Diagram ................................................................. 270 Figure 26.4. Timer 2 16-Bit Mode Block Diagram ................................................. 275 Figure 26.5. Timer 2 8-Bit Mode Block Diagram ................................................... 276 Figure 26.6. Timer 2 External Oscillator Capture Mode Block Diagram ................ 277 Figure 26.7. Timer 3 16-Bit Mode Block Diagram ................................................. 281 Figure 26.8. Timer 3 8-Bit Mode Block Diagram ................................................... 282 Figure 26.9. Timer 3 External Oscillator Capture Mode Block Diagram ................ 283 Figure 27.1. PCA Block Diagram ........................................................................... 287 Figure 27.2. PCA Counter/Timer Block Diagram ................................................... 288 Figure 27.3. PCA Interrupt Block Diagram ............................................................ 289 Figure 27.4. PCA Capture Mode Diagram ............................................................. 291 Figure 27.5. PCA Software Timer Mode Diagram ................................................. 292 Figure 27.6. PCA High-Speed Output Mode Diagram ........................................... 293 Figure 27.7. PCA Frequency Output Mode ........................................................... 294 Figure 27.8. PCA 8-Bit PWM Mode Diagram ........................................................ 295 Figure 27.9. PCA 9, 10 and 11-Bit PWM Mode Diagram ...................................... 296 Figure 27.10. PCA 16-Bit PWM Mode ................................................................... 297 Figure 27.11. PCA Module 2 with Watchdog Timer Enabled ................................ 298 Figure 28.1. Typical C2 Pin Sharing ...................................................................... 309 Rev. 1.2 10

C8051F50x/F51x List of Tables Table 2.1. Product Selection Guide ......................................................................... 21 Table 3.1. Pin Definitions for the C8051F50x-F51x ................................................. 22 Table 4.1. QFP-48 Package Dimensions ................................................................ 30 Table 4.2. QFP-48 Landing Diagram Dimensions ................................................... 31 Table 4.3. QFN-48 Package Dimensions ................................................................ 32 Table 4.4. QFN-48 Landing Diagram Dimensions ................................................... 33 Table 4.5. QFN-40 Package Dimensions ................................................................ 34 Table 4.6. QFN-40 Landing Diagram Dimensions ................................................... 35 Table 4.7. QFP-32 Package Dimensions ................................................................ 36 Table 4.8. QFP-32 Landing Diagram Dimensions ................................................... 37 Table 4.9. QFN-32 Package Dimensions ................................................................ 38 Table 4.10. QFN-32 Landing Diagram Dimensions ................................................. 39 Table 5.1. Absolute Maximum Ratings .................................................................... 40 Table 5.2. Global Electrical Characteristics ............................................................. 41 Table 5.3. Port I/O DC Electrical Characteristics ..................................................... 45 Table 5.4. Reset Electrical Characteristics .............................................................. 46 Table 5.5. Flash Electrical Characteristics .............................................................. 46 Table 5.6. Internal High-Frequency Oscillator Electrical Characteristics ................. 47 Table 5.7. Clock Multiplier Electrical Specifications ................................................ 48 Table 5.8. Voltage Regulator Electrical Characteristics .......................................... 48 Table 5.9. ADC0 Electrical Characteristics .............................................................. 49 Table 5.10. Temperature Sensor Electrical Characteristics .................................... 50 Table 5.11. Voltage Reference Electrical Characteristics ....................................... 50 Table 5.12. Comparator 0 and Comparator 1 Electrical Characteristics ................. 51 Table 11.1. CIP-51 Instruction Set Summary (Prefetch-Enabled) ........................... 89 Table 13.1. Special Function Register (SFR) Memory Map for Pages 0x0 and 0xF ............................................................................. 111 Table 13.2. Special Function Register (SFR) Memory Map for Page 0xC ............ 112 Table 13.3. Special Function Registers ................................................................. 113 Table 14.1. Interrupt Summary .............................................................................. 119 Table 15.1. Flash Security Summary .................................................................... 132 Table 18.1. EMIF Pinout (C8051F500/1/4/5) ......................................................... 149 Table 18.2. EMIF Pinout (C8051F508/9-F510/1) .................................................. 150 Table 18.3. AC Parameters for External Memory Interface ................................... 164 Table 20.1. Port I/O Assignment for Analog Functions ......................................... 179 Table 20.2. Port I/O Assignment for Digital Functions ........................................... 179 Table 20.3. Port I/O Assignment for External Digital Event Capture Functions .... 180 Table 21.1. Baud Rate Calculation Variable Ranges ............................................ 202 Table 21.2. Manual Baud Rate Parameters Examples ......................................... 204 Rev. 1.2 11

C8051F50x/F51x Table 21.3. Autobaud Parameters Examples ........................................................ 205 Table 21.4. LIN Registers (Indirectly Addressable) ............................................... 210 Table 22.1. Background System Information ........................................................ 220 Table 22.2. Standard CAN Registers and Reset Values ....................................... 223 Table 23.1. SMBus Clock Source Selection .......................................................... 230 Table 23.2. Minimum SDA Setup and Hold Times ................................................ 231 Table 23.3. Sources for Hardware Changes to SMB0CN ..................................... 235 Table 23.4. SMBus Status Decoding ..................................................................... 241 Table 24.1. Baud Rate Generator Settings for Standard Baud Rates ................... 244 Table 25.1. SPI Slave Timing Parameters ............................................................ 264 Table 27.1. PCA Timebase Input Options ............................................................. 288 Table 27.2. PCA0CPM and PCA0PWM Bit Settings for PCA Capture/Compare Modules ........................................................ 290 Table 27.3. Watchdog Timer Timeout Intervals1 ................................................... 299 12 Rev. 1.2

C8051F50x/F51x List of Registers SFR Definition 6.4. ADC0CF: ADC0 Configuration ...................................................... 63 SFR Definition 6.5. ADC0H: ADC0 Data Word MSB .................................................... 64 SFR Definition 6.6. ADC0L: ADC0 Data Word LSB ...................................................... 64 SFR Definition 6.7. ADC0CN: ADC0 Control ................................................................ 65 SFR Definition 6.8. ADC0TK: ADC0 Tracking Mode Select ......................................... 66 SFR Definition 6.9. ADC0GTH: ADC0 Greater-Than Data High Byte .......................... 67 SFR Definition 6.10. ADC0GTL: ADC0 Greater-Than Data Low Byte .......................... 67 SFR Definition 6.11. ADC0LTH: ADC0 Less-Than Data High Byte .............................. 68 SFR Definition 6.12. ADC0LTL: ADC0 Less-Than Data Low Byte ............................... 68 SFR Definition 6.13. ADC0MX: ADC0 Channel Select ................................................. 71 SFR Definition 8.1. REF0CN: Reference Control ......................................................... 74 SFR Definition 9.1. CPT0CN: Comparator0 Control ..................................................... 77 SFR Definition 9.2. CPT0MD: Comparator0 Mode Selection ....................................... 78 SFR Definition 9.3. CPT1CN: Comparator1 Control ..................................................... 79 SFR Definition 9.4. CPT1MD: Comparator1 Mode Selection ....................................... 80 SFR Definition 9.5. CPT0MX: Comparator0 MUX Selection ........................................ 82 SFR Definition 9.6. CPT1MX: Comparator1 MUX Selection ........................................ 83 SFR Definition 10.1. REG0CN: Regulator Control ........................................................ 85 SFR Definition 11.1. DPL: Data Pointer Low Byte ........................................................ 93 SFR Definition 11.2. DPH: Data Pointer High Byte ....................................................... 93 SFR Definition 11.3. SP: Stack Pointer ......................................................................... 94 SFR Definition 11.4. ACC: Accumulator ....................................................................... 94 SFR Definition 11.5. B: B Register ................................................................................ 94 SFR Definition 11.6. PSW: Program Status Word ........................................................ 95 SFR Definition 11.7. SNn: Serial Number n .................................................................. 96 SFR Definition 13.1. SFR0CN: SFR Page Control ..................................................... 107 SFR Definition 13.2. SFRPAGE: SFR Page ............................................................... 108 SFR Definition 13.3. SFRNEXT: SFR Next ................................................................ 109 SFR Definition 13.4. SFRLAST: SFR Last .................................................................. 110 SFR Definition 14.1. IE: Interrupt Enable .................................................................... 121 SFR Definition 14.2. IP: Interrupt Priority .................................................................... 122 SFR Definition 14.3. EIE1: Extended Interrupt Enable 1 ............................................ 123 SFR Definition 14.4. EIP1: Extended Interrupt Priority 1 ............................................ 124 SFR Definition 14.5. EIE2: Extended Interrupt Enable 2 ............................................ 125 SFR Definition 14.6. EIP2: Extended Interrupt Priority Enabled 2 .............................. 126 SFR Definition 14.7. IT01CF: INT0/INT1 Configuration .............................................. 128 SFR Definition 15.1. PSCTL: Program Store R/W Control ......................................... 134 SFR Definition 15.2. FLKEY: Flash Lock and Key ...................................................... 135 SFR Definition 15.3. FLSCL: Flash Scale ................................................................... 136 SFR Definition 15.4. CCH0CN: Cache Control ........................................................... 137 SFR Definition 15.5. ONESHOT: Flash Oneshot Period ............................................ 137 SFR Definition 16.1. PCON: Power Control ................................................................ 140 SFR Definition 17.1. VDM0CN: VDD Monitor Control ................................................ 144 Rev. 1.2 13

C8051F50x/F51x SFR Definition 17.2. RSTSRC: Reset Source ............................................................ 146 SFR Definition 18.1. EMI0CN: External Memory Interface Control ............................ 151 SFR Definition 18.2. EMI0CF: External Memory Configuration .................................. 152 SFR Definition 18.3. EMI0TC: External Memory Timing Control ................................ 157 SFR Definition 19.1. CLKSEL: Clock Select ............................................................... 166 SFR Definition 19.2. OSCICN: Internal Oscillator Control .......................................... 168 SFR Definition 19.3. OSCICRS: Internal Oscillator Coarse Calibration ...................... 169 SFR Definition 19.4. OSCIFIN: Internal Oscillator Fine Calibration ............................ 169 SFR Definition 19.5. CLKMUL: Clock Multiplier .......................................................... 171 SFR Definition 19.6. OSCXCN: External Oscillator Control ........................................ 173 SFR Definition 20.1. XBR0: Port I/O Crossbar Register 0 .......................................... 184 SFR Definition 20.2. XBR1: Port I/O Crossbar Register 1 .......................................... 185 SFR Definition 20.3. XBR2: Port I/O Crossbar Register 1 .......................................... 186 SFR Definition 20.4. P0MASK: Port 0 Mask Register ................................................. 187 SFR Definition 20.5. P0MAT: Port 0 Match Register .................................................. 187 SFR Definition 20.6. P1MASK: Port 1 Mask Register ................................................. 188 SFR Definition 20.7. P1MAT: Port 1 Match Register .................................................. 188 SFR Definition 20.8. P2MASK: Port 2 Mask Register ................................................. 189 SFR Definition 20.9. P2MAT: Port 2 Match Register .................................................. 189 SFR Definition 20.10. P3MASK: Port 3 Mask Register ............................................... 190 SFR Definition 20.11. P3MAT: Port 3 Match Register ................................................ 190 SFR Definition 20.12. P0: Port 0 ................................................................................. 191 SFR Definition 20.13. P0MDIN: Port 0 Input Mode ..................................................... 192 SFR Definition 20.14. P0MDOUT: Port 0 Output Mode .............................................. 192 SFR Definition 20.15. P0SKIP: Port 0 Skip ................................................................. 193 SFR Definition 20.16. P1: Port 1 ................................................................................. 193 SFR Definition 20.17. P1MDIN: Port 1 Input Mode ..................................................... 194 SFR Definition 20.18. P1MDOUT: Port 1 Output Mode .............................................. 194 SFR Definition 20.19. P1SKIP: Port 1 Skip ................................................................. 195 SFR Definition 20.20. P2: Port 2 ................................................................................. 195 SFR Definition 20.21. P2MDIN: Port 2 Input Mode ..................................................... 196 SFR Definition 20.22. P2MDOUT: Port 2 Output Mode .............................................. 196 SFR Definition 20.23. P2SKIP: Port 2 Skip ................................................................. 197 SFR Definition 20.24. P3: Port 3 ................................................................................. 197 SFR Definition 20.25. P3MDIN: Port 3 Input Mode ..................................................... 198 SFR Definition 20.26. P3MDOUT: Port 3 Output Mode .............................................. 198 SFR Definition 20.27. P3SKIP: Port 3Skip .................................................................. 199 SFR Definition 20.28. P4: Port 4 ................................................................................. 199 SFR Definition 20.29. P4MDOUT: Port 4 Output Mode .............................................. 200 SFR Definition 21.1. LIN0ADR: LIN0 Indirect Address Register ................................. 208 SFR Definition 21.2. LIN0DAT: LIN0 Indirect Data Register ....................................... 208 SFR Definition 21.3. LIN0CF: LIN0 Control Mode Register ........................................ 209 SFR Definition 22.1. CAN0CFG: CAN Clock Configuration ........................................ 225 SFR Definition 23.1. SMB0CF: SMBus Clock/Configuration ...................................... 232 SFR Definition 23.2. SMB0CN: SMBus Control .......................................................... 234 14 Rev. 1.2

C8051F50x/F51x SFR Definition 23.3. SMB0DAT: SMBus Data ............................................................ 236 SFR Definition 24.1. SCON0: Serial Port 0 Control .................................................... 248 SFR Definition 24.2. SMOD0: Serial Port 0 Control .................................................... 249 SFR Definition 24.3. SBUF0: Serial (UART0) Port Data Buffer .................................. 250 SFR Definition 24.4. SBCON0: UART0 Baud Rate Generator Control ...................... 250 SFR Definition 24.6. SBRLL0: UART0 Baud Rate Generator Reload Low Byte ........ 251 SFR Definition 24.5. SBRLH0: UART0 Baud Rate Generator Reload High Byte ....... 251 SFR Definition 25.1. SPI0CFG: SPI0 Configuration ................................................... 259 SFR Definition 25.2. SPI0CN: SPI0 Control ............................................................... 260 SFR Definition 25.3. SPI0CKR: SPI0 Clock Rate ....................................................... 261 SFR Definition 25.4. SPI0DAT: SPI0 Data ................................................................. 261 SFR Definition 26.1. CKCON: Clock Control .............................................................. 266 SFR Definition 26.2. TCON: Timer Control ................................................................. 271 SFR Definition 26.3. TMOD: Timer Mode ................................................................... 272 SFR Definition 26.4. TL0: Timer 0 Low Byte ............................................................... 273 SFR Definition 26.5. TL1: Timer 1 Low Byte ............................................................... 273 SFR Definition 26.6. TH0: Timer 0 High Byte ............................................................. 274 SFR Definition 26.7. TH1: Timer 1 High Byte ............................................................. 274 SFR Definition 26.8. TMR2CN: Timer 2 Control ......................................................... 278 SFR Definition 26.9. TMR2RLL: Timer 2 Reload Register Low Byte .......................... 279 SFR Definition 26.10. TMR2RLH: Timer 2 Reload Register High Byte ...................... 279 SFR Definition 26.11. TMR2L: Timer 2 Low Byte ....................................................... 280 SFR Definition 26.12. TMR2H Timer 2 High Byte ....................................................... 280 SFR Definition 26.13. TMR3CN: Timer 3 Control ....................................................... 284 SFR Definition 26.14. TMR3RLL: Timer 3 Reload Register Low Byte ........................ 285 SFR Definition 26.15. TMR3RLH: Timer 3 Reload Register High Byte ...................... 285 SFR Definition 26.16. TMR3L: Timer 3 Low Byte ....................................................... 286 SFR Definition 26.17. TMR3H Timer 3 High Byte ....................................................... 286 SFR Definition 27.1. PCA0CN: PCA Control .............................................................. 300 SFR Definition 27.2. PCA0MD: PCA Mode ................................................................ 301 SFR Definition 27.3. PCA0PWM: PCA PWM Configuration ....................................... 302 SFR Definition 27.4. PCA0CPMn: PCA Capture/Compare Mode .............................. 303 SFR Definition 27.5. PCA0L: PCA Counter/Timer Low Byte ...................................... 304 SFR Definition 27.6. PCA0H: PCA Counter/Timer High Byte ..................................... 304 SFR Definition 27.7. PCA0CPLn: PCA Capture Module Low Byte ............................. 305 SFR Definition 27.8. PCA0CPHn: PCA Capture Module High Byte ........................... 305 C2 Register Definition 28.1. C2ADD: C2 Address ...................................................... 306 C2 Register Definition 28.2. DEVICEID: C2 Device ID ............................................... 307 C2 Register Definition 28.3. REVID: C2 Revision ID .................................................. 307 C2 Register Definition 28.4. FPCTL: C2 Flash Programming Control ........................ 308 C2 Register Definition 28.5. FPDAT: C2 Flash Programming Data ............................ 308 Rev. 1.2 15

C8051F50x/F51x 1. System Overview C8051F50x/F51x devices are fully integrated mixed-signal System-on-a-Chip MCUs. Highlighted features are listed below. Refer to Table 2.1 for specific product feature selection and part ordering numbers.  High-speed pipelined 8051-compatible microcontroller core (up to 50 MIPS)  In-system, full-speed, non-intrusive debug interface (on-chip)  Controller Area Network (CAN 2.0B) Controller with 32 message objects, each with its own indentifier mask (C8051F500/2/4/6/8-F510)  LIN 2.1 peripheral (fully backwards compatible, master and slave modes) (C8051F500/2/4/6/8-F510)  True 12-bit 200 ksps 32-channel single-ended ADC with analog multiplexer  Precision programmable 24 MHz internal oscillator that is within ±0.5% across the temperature range and for VDD voltages greater than or equal to the on-chip voltage regulator minimum output at the low setting. The oscillator is within +1.0% for VDD voltages below this minimum output setting.  On-chip Clock Multiplier to reach up to 50 MHz  64 kB (C8051F500/1/2/3/8/9) or 32 kB (C8051F504/5/6/7-F510/1) of on-chip Flash memory  4352 bytes of on-chip RAM  SMBus/I2C, Enhanced UART, and Enhanced SPI serial interfaces implemented in hardware  Four general-purpose 16-bit timers  External Data Memory Interface (C8051F500/1/4/5 and C8051F508/9-F510/1) with 64 kB address space  Programmable Counter/Timer Array (PCA) with six capture/compare modules and Watchdog Timer function  On-chip Voltage Regulator  On-chip Power-On Reset, VDD Monitor, and Temperature Sensor  On-chip Voltage Comparator  40, 33, or 25 Port I/O (5 V push-pull) With on-chip Voltage Regulator, Power-On Reset, V monitor, Watchdog Timer, and clock oscillator, the DD C8051F50x/F51x devices are truly stand-alone System-on-a-Chip solutions. The Flash memory can be reprogrammed even in-circuit, providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. User software has complete control of all peripherals, and may individually shut down any or all peripherals for power savings. The on-chip Silicon Labs 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip resources), full speed, in-circuit debugging using the production MCU installed in the final application. This debug logic supports inspection and modification of memory and registers, setting breakpoints, single stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging using C2. The two C2 interface pins can be shared with user functions, allowing in-system debugging with- out occupying package pins. The devices are specified for 1.8 V to 5.25 V operation over the automotive temperature range (–40 to +125 °C). The Port I/O and RST pins can interface to 5 V logic by setting the VIO pin to 5 V. The C8051F500/1/4/5 devices are available in 48-pin QFP and QFN packages, the C8051F508/9-F510/1 are available in 40-pin QFN packages, and the C8051F502/3/6/7 devices are available in 32-pin QFP and QFN packages. All package options are lead-free and RoHS compliant. See Table 2.1 for ordering infor- mation. Block diagrams are included in Figure 1.1, Figure 1.2, and Figure 1.3. Rev. 1.2 16

C8051F50x/F51x VIO Power On CIP-51 8051 Port I/O Configuration Reset Controller Core P0.0 Digital Peripherals P0.1 Reset up to 64kB Byte Flash P0.2 UART0 Program Memory Port 0 P0.3 C2CK/RST ProDgerabmugm /i ng Timers 0, Drivers P0.4 C2D Hardware 256 Byte RAM 1, 2, 3 P0.5 P0.6 PCA P0.7 4 kB XRAM Priority WDT Crossbar P1.0 LIN 2.1 Decoder P1.1 P1.2 VREGIN Voltage Regulator CAN 2.0B Port 1 P1.3 (LDO) Drivers P1.4 SPI P1.5 VDD I2C P1.6 GND P1.7 Crossbar Control SFR P2.0 Bus External Memory Interface P2.1 System Clock Setup *On F500/4 Devices P2.2 XTAL1 XTAL2 Port 2 P2.3 Drivers P2.4 Analog Peripherals Internal Oscillator External Oscillator P2.5 P2.6 Voltage P2.7 Clock Multiplier Reference VREF P3.0 P3.1 P3.2 VDD VREF Port 3 P3.3 VDD Drivers P3.4 12-bit A VREF P3.5 200ksps M P0 – P3 P3.6 ADC U Temp P3.7 X Sensor GND P4.0 P4.1 P4.2 CP0, CP0A + Port 4 P4.3 VDDA Comparator 0 - Drivers P4.4 GNDA P4.5 CP1, CP1A + P4.6 Comparator 1 - P4.7 Figure 1.1. C8051F500/1/4/5 Block Diagram 17 Rev. 1.2

C8051F50x/F51x VIO Power On CIP-51 8051 Port I/O Configuration Reset Controller Core P0.0 Digital Peripherals P0.1 Reset up to 64 kB Byte Flash P0.2 Program Memory UART0 Port 0 P0.3 C2CK/RST Debug / Drivers P0.4 Programming Timers 0, Hardware 256 Byte RAM 1, 2, 3 P0.5 P0.6/ P0.7 4 kB XRAM 6 channel Priority C2D PCA/WDT Crossbar P1.0 Decoder P1.1 LIN 2.1 P1.2 VREGIN Voltage Regulator CAN 2.0B Port 1 P1.3 (LDO) Drivers P1.4 SPI P1.5 VDD I2C P1.6 GND P1.7 SFR Crossbar Control P2.0 Bus External Memory Interface P2.1 System Clock Setup *On ‘F508-F510 devices P2.2 XTAL1 XTAL2 Port 2 P2.3 Drivers P2.4 Analog Peripherals Internal Oscillator External Oscillator P2.5 P2.6 Voltage P2.7 Clock Multiplier Reference VREF P3.0 P3.1 P3.2 VDD VREF Port 3 P3.3 VDD Drivers P3.4 12-bit A VREF P3.5 200ksps M P0 – P3 P3.6 ADC U Temp P3.7 X Sensor GND P4.0 / C2D Port 4 Driver CP0, CP0A + VDDA Comparator 0 - GNDA CP1, CP1A + Comparator 1 - Figure 1.2. C8051F508/9-F510/1 Block Diagram Rev. 1.2 18

C8051F50x/F51x VIO Power On CIP-51 8051 Port I/O Configuration Reset Controller Core P0.0 Digital Peripherals P0.1 Reset up to 64kB Byte Flash UART0 P0.2 Program Memory Port 0 P0.3 C2CK/RST ProDgerabmugm /i ng Timers 0, Drivers P0.4 Hardware 256 Byte RAM 1, 2, 3 P0.5 P0.6 PCA/ P0.7 4 kB XRAM Priority C2D WDT Crossbar P1.0 LIN 2.1 Decoder P1.1 P1.2 VREGIN Voltage Regulator CAN 2.0B Port 1 P1.3 (LDO) Drivers P1.4 SPI P1.5 VDD I2C P1.6 GND P1.7 SFR Crossbar Control P2.0 Bus P2.1 System Clock Setup *On F502/6 Devices P2.2 XTAL1 XTAL2 Port 2 P2.3 Drivers P2.4 Analog Peripherals Internal Oscillator External Oscillator P2.5 P2.6 Voltage P2.7 Clock Multiplier Reference VREF P3.0 / C2D Port 3 Drivers VDD VREF VDD 12-bit A VREF 200ksps M P0 – P3 ADC U Temp X Sensor GND CP0, CP0A + VDDA Comparator 0 - GNDA CP1, CP1A + Comparator 1 - Figure 1.3. C8051F502/3/6/7 Block Diagram 19 Rev. 1.2

C8051F50x/F51x 2. Ordering Information The following features are common to all devices in this family:  50 MHz system clock and 50 MIPS throughput (peak)  4352 bytes of RAM (256 internal bytes and 4096 XRAM bytes)  SMBus/I2C, Enhanced SPI, Enhanced UART  Four Timers  Six Programmable Counter Array channels  Internal 24 MHz oscillator  Internal Voltage Regulator  12-bit, 200 ksps ADC  Internal Voltage Reference and Temperature Sensor  Two Analog Comparators Table 2.1 shows the feature that differentiate the devices in this family. Rev. 1.2 20

C8051F50x/F51x Table 2.1. Product Selection Guide e e c c a a f f r r r r e e e e b t b t m ) n m ) n u kB y I u kB y I Part N mory ( rt I/Os Memor Part N mory ( rt I/Os Memor Ordering Flash Me CAN2.0B LIN2.0 Digital Po External Package Ordering Flash Me CAN2.0B LIN2.0 Digital Po External Package C8051F500-IQ 64   40  QFP-48 C8051F505-IQ 32 — — 40  QFP-48 C8051F500-IM 64   40  QFN-48 C8051F505-IM 32 — — 40  QFN-48 C8051F501-IQ 64 — — 40  QFP-48 C8051F506-IQ 32   25 — QFP-32 C8051F501-IM 64 — — 40  QFN-48 C8051F506-IM 32   25 — QFN-32 C8051F502-IQ 64   25 — QFP-32 C8051F507-IQ 32 — — 25 — QFP-32 C8051F502-IM 64   25 — QFN-32 C8051F507-IM 32 — — 25 — QFN-32 C8051F503-IQ 64 — — 25 — QFP-32 C8051F508-IM 64   33  QFN-40 C8051F503-IM 64 — — 25 — QFN-32 C8051F509-IM 64 — — 33  QFN-40 C8051F504-IQ 32   40  QFP-48 C8051F510-IM 32   33  QFN-40 C8051F504-IM 32   40  QFN-48 C8051F511-IM 32 — — 33  QFN-40 Note: The suffix of the part number indicates the device rating and the package. All devices are RoHS compliant. All of these devices are also available in an automotive version. For the automotive version, the -I in the ordering part number is replaced with -A. For example, the automotive version of the C8051F500-IM is the C8051F500-AM. The -AM and -AQ devices receive full automotive quality production status, including AEC-Q100 qualifica- tion, registration with International Material Data System (IMDS) and Part Production Approval Process (PPAP) documentation. PPAP documentation is available at www.silabs.com with a registered and NDA approved user account. The -AM and -AQ devices enable high volume automotive OEM applications with their enhanced testing and processing. Please contact Silicon Labs sales for more information regarding –AM and -AQ devices for your automotive project. 21 Rev. 1.2

C8051F50x/F51x 3. Pin Definitions Table 3.1. Pin Definitions for the C8051F50x/F51x Name Pin Pin Pin Type Description ‘F500/1/4/5 F508/9- ‘F502/3/6/7 F510/1 (48-pin) (40-pin) (32-pin) VDD 4 4 4 Digital Supply Voltage. Must be connected. GND 6 6 6 Digital Ground. Must be connected. VDDA 5 5 5 Analog Supply Voltage. Must be connected. GNDA 7 7 7 Analog Ground. Must be connected. VREGIN 3 3 3 Voltage Regulator Input VIO 2 2 2 Port I/O Supply Voltage. Must be connected. RST/ 12 10 10 D I/O Device Reset. Open-drain output of internal POR or V Monitor. An external source DD can initiate a system reset by driving this pin low. C2CK D I/O Clock signal for the C2 Debug Interface. C2D 11 — — D I/O Bi-directional data signal for the C2 Debug Interface. P4.0/ — 9 — D I/O or A In Port 4.0. See SFR Definition 20.29 for a description. C2D D I/O Bi-directional data signal for the C2 Debug Interface. P3.0/ — 9 D I/O or A In Port 3.0. See SFR Definition 20.24 for a description. C2D D I/O Bi-directional data signal for the C2 Debug Interface. P0.0 8 8 8 D I/O or A In Port 0.0. See SFR Definition 20.12 for a description. P0.1 1 1 1 D I/O or A In Port 0.1 P0.2 48 40 32 D I/O or A In Port 0.2 P0.3 47 39 31 D I/O or A In Port 0.3 P0.4 46 38 30 D I/O or A In Port 0.4 P0.5 45 37 29 D I/O or A In Port 0.5 Rev. 1.2 22

C8051F50x/F51x Table 3.1. Pin Definitions for the C8051F50x/F51x(Continued) Name Pin Pin Pin Type Description ‘F500/1/4/5 F508/9- ‘F502/3/6/7 F510/1 (48-pin) (40-pin) (32-pin) P0.6 44 36 28 D I/O or A In Port 0.6 P0.7 43 35 27 D I/O or A In Port 0.7 P1.0 42 34 26 D I/O or A In Port 1.0. See SFR Definition 20.16 for a description. P1.1 41 33 25 D I/O or A In Port 1.1. P1.2 40 32 24 D I/O or A In Port 1.2. P1.3 39 31 23 D I/O or A In Port 1.3. P1.4 38 30 22 D I/O or A In Port 1.4. P1.5 37 29 21 D I/O or A In Port 1.5. P1.6 36 28 20 D I/O or A In Port 1.6. P1.7 35 27 19 D I/O or A In Port 1.7. P2.0 34 26 18 D I/O or A In Port 2.0. See SFR Definition 20.20 for a description. P2.1 33 25 17 D I/O or A In Port 2.1. P2.2 32 24 16 D I/O or A In Port 2.2. P2.3 31 23 15 D I/O or A In Port 2.3. P2.4 30 22 14 D I/O or A In Port 2.4. P2.5 29 21 13 D I/O or A In Port 2.5. P2.6 28 20 12 D I/O or A In Port 2.6. P2.7 27 19 11 D I/O or A In Port 2.7. P3.0 26 18 — D I/O or A In Port 3.0. See SFR Definition 20.24 for a description. P3.1 25 17 — D I/O or A In Port 3.1. P3.2 24 16 — D I/O or A In Port 3.2. P3.3 23 15 — D I/O or A In Port 3.3. P3.4 22 14 — D I/O or A In Port 3.4. P3.5 21 13 — D I/O or A In Port 3.5. P3.6 20 12 — D I/O or A In Port 3.6. 23 Rev. 1.2

C8051F50x/F51x Table 3.1. Pin Definitions for the C8051F50x/F51x(Continued) Name Pin Pin Pin Type Description ‘F500/1/4/5 F508/9- ‘F502/3/6/7 F510/1 (48-pin) (40-pin) (32-pin) P3.7 19 11 — D I/O Port 3.7. P4.0 18 — — D I/O Port 4.0. See SFR Definition 20.28 for a description. P4.1 17 — — D I/O Port 4.1. P4.2 16 — — D I/O Port 4.2. P4.3 15 — — D I/O Port 4.3. P4.4 14 — — D I/O Port 4.4. P4.5 13 — — D I/O Port 4.5. P4.6 10 — — D I/O Port 4.6. P4.7 9 — — D I/O Port 4.7. Rev. 1.2 24

C8051F50x/F51x X X T R AL1 AL2 RT0 RT0 N TX N RX T T A A A A X X U U C C 2/ 3/ 4/ 5/ 6/ 7/ 0 1 2 3 4 5 0. 0. 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. P P P P P P P P P P P P 8 7 6 5 4 3 2 1 0 9 8 7 4 4 4 4 4 4 4 4 4 3 3 3 P0.1/CNVSTR 1 36 P1.6 VIO 2 35 P1.7 VREGIN 3 34 P2.0 VDD 4 C8051F500-IQ 33 P2.1 VDDA 5 C8051F501-IQ 32 P2.2 GND 6 31 P2.3 C8051F504-IQ GNDA 7 30 P2.4 C8051F505-IQ P0.0 / VREF 8 29 P2.5 Top View P4.7 9 28 P2.6 P4.6 10 27 P2.7 C2D 11 26 P3.0 RST/C2CK 12 25 P3.1 3 4 5 6 7 8 9 0 1 2 3 4 1 1 1 1 1 1 1 2 2 2 2 2 5 4 3 2 1 0 7 6 5 4 3 2 4. 4. 4. 4. 4. 4. 3. 3. 3. 3. 3. 3. P P P P P P P P P P P P Figure 3.1. QFP-48 Pinout Diagram (Top View) 25 Rev. 1.2

C8051F50x/F51x X X T R AL1 AL2 RT0 RT0 N TX N RX T T A A A A X X U U C C 2/ 3/ 4/ 5/ 6/ 7/ 0 1 2 3 4 5 0. 0. 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. P P P P P P P P P P P P 8 7 6 5 4 3 2 1 0 9 8 7 4 4 4 4 4 4 4 4 4 3 3 3 P0.1/CNVSTR 1 36 P1.6 VIO 2 35 P1.7 VREGIN 3 34 P2.0 VDD 4 33 P2.1 C8051F500-IM VDDA 5 32 P2.2 C8051F501-IM GND 6 31 P2.3 C8051F504-IM GNDA 7 30 P2.4 C8051F505-IM P0.0 / VREF 8 Top View 29 P2.5 P4.7 9 28 P2.6 GND P4.6 10 27 P2.7 C2D 11 26 P3.0 RST/C2CK 12 25 P3.1 3 4 5 6 7 8 9 0 1 2 3 4 1 1 1 1 1 1 1 2 2 2 2 2 5 4 3 2 1 0 7 6 5 4 3 2 4. 4. 4. 4. 4. 4. 3. 3. 3. 3. 3. 3. P P P P P P P P P P P P Figure 3.2. QFN-48 Pinout Diagram (Top View) Rev. 1.2 26

C8051F50x/F51x X X T R X X AL1 AL2 RT0 RT0 N T N R T T A A A A X X U U C C / / / / / / 2 3 4 5 6 7 0 1 2 3 0. 0. 0. 0. 0. 0. 1. 1. 1. 1. P P P P P P P P P P 0 9 8 7 6 5 4 3 2 1 4 3 3 3 3 3 3 3 3 3 P0.1 / CNVSTR 1 30 P1.4 VIO 2 29 P1.5 VREGIN 3 28 P1.6 C8051F508-IM VDD 4 27 P1.7 C8051F509-IM VDDA 5 C8051F510-IM 26 P2.0 GND 6 C8051F511-IM 25 P2.1 Top View GNDA 7 24 P2.2 P0.0 / VREF 8 23 P2.3 GND P4.0 / C2D 9 22 P2.4 RST / C2CK 10 21 P2.5 1 2 3 4 5 6 7 8 9 0 1 1 1 1 1 1 1 1 1 2 7 6 5 4 3 2 1 0 7 6 . . . . . . . . . . 3 3 3 3 3 3 3 3 2 2 P P P P P P P P P P Figure 3.3. QFN-40 Pinout Diagram (Top View) 27 Rev. 1.2

C8051F50x/F51x X X T R AL1 AL2 RT0 RT0 N TX N RX T T A A A A X X U U C C 2/ 3/ 4/ 5/ 6/ 7/ 0 1 0. 0. 0. 0. 0. 0. 1. 1. P P P P P P P P 2 1 0 9 8 7 6 5 3 3 3 2 2 2 2 2 P0.1/CNVSTR 1 24 P1.2 VIO 2 23 P1.3 C8051F502-IQ VREGIN 3 22 P1.4 C8051F503-IQ VDD 4 21 P1.5 C8051F506-IQ VDDA 5 C8051F507-IQ 20 P1.6 Top View GND 6 19 P1.7 GNDA 7 18 P2.0 P0.0/VREF 8 17 P2.1 9 10 11 12 13 14 15 16 D K 7 6 5 4 3 2 2 C 2. 2. 2. 2. 2. 2. C 2 P P P P P P 0/ C 3. T/ P S R Figure 3.4. QFP-32 Pinout Diagram (Top View) Rev. 1.2 28

C8051F50x/F51x X X T R X X 1 2 0 0 T R L L T T A A R R N N T T A A A A X X U U C C / / / / / / 2 3 4 5 6 7 0 1 . . . . . . . . 0 0 0 0 0 0 1 1 P P P P P P P P 2 1 0 9 8 7 6 5 3 3 3 2 2 2 2 2 P0.1/CNVSTR 1 24 P1.2 VIO 2 23 P1.3 C8051F502-IM VREGIN 3 22 P1.4 C8051F503-IM VDD 4 21 P1.5 C8051F506-IM VDDA 5 C8051F507-IM 20 P1.6 GND 6 Top View 19 P1.7 GNDA 7 18 P2.0 GND P0.0/VREF 8 17 P2.1 0 1 2 3 4 5 6 9 1 1 1 1 1 1 1 D K 7 6 5 4 3 2 2 C 2. 2. 2. 2. 2. 2. C 2 P P P P P P / C 0 3. T/ P S R Figure 3.5. QFN-32 Pinout Diagram (Top View) 29 Rev. 1.2

C8051F50x/F51x 4. Package Specifications 4.1. QFP-48 Package Specifications Figure 4.1. QFP-48 Package Drawing Table 4.1. QFP-48 Package Dimensions Dimension Min Typ Max Dimension Min Typ Max A — — 1.20 E 9.00 BSC. A1 0.05 — 0.15 E1 7.00 BSC. A2 0.95 1.00 1.05 L 0.45 0.60 0.75 b 0.17 0.22 0.27 aaa 0.20 c 0.09 — 0.20 bbb 0.20 D 9.00 BSC. ccc 0.08 D1 7.00 BSC. ddd 0.08 e 0.50 BSC. θ 0° 3.5° 7° Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to the JEDEC outline MS-026, variation ABC. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.2 30

C8051F50x/F51x Figure 4.2. QFP-48 Landing Diagram Table 4.2. QFP-48 Landing Diagram Dimensions Dimension Min Max Dimension Min Max C1 8.30 8.40 X1 0.20 0.30 C2 8.30 8.40 Y1 1.40 1.50 E 0.50 BSC Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. This Land Pattern Design is based on the IPC-7351 guidelines. Solder Mask Design 3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60μm minimum, all the way around the pad. Stencil Design 4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 5. The stencil thickness should be 0.125mm (5 mils). 6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads. Card Assembly 7. A No-Clean, Type-3 solder paste is recommended. 8. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. 31 Rev. 1.2

C8051F50x/F51x 4.2. QFN-48 Package Specifications Figure 4.3. QFN-48 Package Drawing Table 4.3. QFN-48 Package Dimensions Dimension Min Typ Max Dimension Min Typ Max A 0.80 0.90 1.00 E2 3.90 4.00 4.10 A1 0.00 - 0.05 L 0.30 0.40 0.50 b 0.18 0.23 0.30 L1 0.00 - 0.08 D 7.00 BSC aaa - - 0.10 D2 3.90 4.00 4.10 bbb - - 0.10 e 0.50 BSC ddd - - 0.05 E 7.00 BSC eee - - 0.08 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to JEDEC outline MO-220, variation VKKD-4 except for features D2 and L which are toleranced per supplier designation. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.2 32

C8051F50x/F51x Figure 4.4. QFN-48 Landing Diagram Table 4.4. QFN-48 Landing Diagram Dimensions Dimension Min Max Dimension Min Max C1 6.80 6.90 X2 4.00 4.10 C2 6.80 6.90 Y1 0.75 0.85 e 0.50 BSC Y2 4.00 4.10 X1 0.20 0.30 Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimension and Tolerancing is per the ANSI Y14.5M-1994 specification. 3. This Land Pattern Design is based on the IPC-SM-7351 guidelines. 4. All dimensions shown are at Maximum Material Condition (MMC). Least Material Condition (LMC) is calculated based on a Fabrication Allowance of 0.05 mm. Solder Mask Design 5. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60 μm minimum, all the way around the pad. Stencil Design 6. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 7. The stencil thickness should be 0.125 mm (5 mils). 8. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads. 9. A 3x3 array of 1.20 mm x 1.10 mm openings on a 1.40 mm pitch should be used for the center pad. Card Assembly 10. A No-Clean, Type-3 solder paste is recommended. 11. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. 33 Rev. 1.2

C8051F50x/F51x 4.3. QFN-40 Package Specifications Figure 4.5. Typical QFN-40 Package Drawing Table 4.5. QFN-40 Package Dimensions Dimension Min Typ Max Dimension Min Typ Max A 0.80 0.85 0.90 E2 4.00 4.10 4.20 A1 0.00 0.05 L 0.35 0.40 0.45 b 0.18 0.23 0.28 L1 0.10 D 6.00 BSC aaa 0.10 D2 4.00 4.10 4.20 bbb 0.10 e 0.50 BSC ddd 0.05 E 6.00 BSC eee 0.08 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to JEDEC Solid State Outline MO-220, variation VJJD-5, except for features A, D2, and E2 which are toleranced per supplier designation. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.2 34

C8051F50x/F51x Figure 4.6. QFN-40 Landing Diagram Table 4.6. QFN-40 Landing Diagram Dimensions Dimension Min Max Dimension Min Max C1 5.80 5.90 X2 4.10 4.20 C2 5.80 5.90 Y1 0.75 0.85 e 0.50 BSC Y2 4.10 4.20 X1 0.15 0.25 Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimension and Tolerancing is per the ANSI Y14.5M-1994 specification. 3. This Land Pattern Design is based on the IPC-SM-7351 guidelines. 4. All dimensions shown are at Maximum Material Condition (MMC). Least Material Condition (LMC) is calculated based on a Fabrication Allowance of 0.05 mm. Solder Mask Design 5. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60 μm minimum, all the way around the pad. Stencil Design 6. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 7. The stencil thickness should be 0.125 mm (5 mils). 8. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads. 9. A 4x4 array of 0.80 mm square openings on a 1.05 mm pitch should be used for the center ground pad. Card Assembly 10. A No-Clean, Type-3 solder paste is recommended. 11. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. 35 Rev. 1.2

C8051F50x/F51x 4.4. QFP-32 Package Specifications Figure 4.7. QFP-32 Package Drawing Table 4.7. QFP-32 Package Dimensions Dimension Min Typ Max Dimension Min Typ Max A — — 1.60 E 9.00 BSC. A1 0.05 — 0.15 E1 7.00 BSC. A2 1.35 1.40 1.45 L 0.45 0.60 0.75 b 0.30 0.37 0.45 aaa 0.20 c 0.09 — 0.20 bbb 0.20 D 9.00 BSC. ccc 0.10 D1 7.00 BSC. ddd 0.20 e 0.80 BSC. θ 0° 3.5° 7° Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to the JEDEC outline MS-026, variation BBA. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.2 36

C8051F50x/F51x Figure 4.8. QFP-32 Package Drawing Table 4.8. QFP-32 Landing Diagram Dimensions Dimension Min Max Dimension Min Max C1 8.40 8.50 X1 0.40 0.50 C2 8.40 8.50 Y1 1.25 1.35 E 0.80 BSC Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. This Land Pattern Design is based on the IPC-7351 guidelines. Solder Mask Design 3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60μm minimum, all the way around the pad. Stencil Design 4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 5. The stencil thickness should be 0.125 mm (5 mils). 6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads. Card Assembly 7. A No-Clean, Type-3 solder paste is recommended. 8. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. 37 Rev. 1.2

C8051F50x/F51x 4.5. QFN-32 Package Specifications Figure 4.9. QFN-32 Package Drawing Table 4.9. QFN-32 Package Dimensions Dimension Min Typ Max Dimension Min Typ Max A 0.80 0.9 1.00 E2 3.20 3.30 3.40 A1 0.00 0.02 0.05 L 0.30 0.40 0.50 b 0.18 0.25 0.30 L1 0.00 — 0.15 D 5.00 BSC. aaa — — 0.15 D2 3.20 3.30 3.40 bbb — — 0.15 e 0.50 BSC. ddd — — 0.05 E 5.00 BSC. eee — — 0.08 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to the JEDEC Solid State Outline MO-220, variation VGGD except for custom features D2, E2, and L which are toleranced per supplier designation. 4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.2 38

C8051F50x/F51x Figure 4.10. QFN-32 Package Drawing Table 4.10. QFN-32 Landing Diagram Dimensions Dimension Min Max Dimension Min Max C1 4.80 4.90 X2 3.20 3.40 C2 4.80 4.90 Y1 0.75 0.85 e 0.50 BSC Y2 3.20 3.40 X1 0.20 0.30 Notes: General 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. This Land Pattern Design is based on the IPC-7351 guidelines. Solder Mask Design 3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60μm minimum, all the way around the pad. Stencil Design 4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 5. The stencil thickness should be 0.125mm (5 mils). 6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads. 7. A 3x3 array of 1.0 mm openings on a 1.20 mm pitch should be used for the center ground pad. Card Assembly 8. A No-Clean, Type-3 solder paste is recommended. 9. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. 39 Rev. 1.2

C8051F50x/F51x 5. Electrical Characteristics 5.1. Absolute Maximum Specifications Table 5.1. Absolute Maximum Ratings Parameter Conditions Min Typ Max Units Ambient Temperature under Bias –55 — 135 °C Storage Temperature –65 — 150 °C Voltage on V with Respect to GND –0.3 — 5.5 V REGIN Voltage on V with Respect to GND –0.3 — 2.8 V DD Voltage on VDDA with Respect to GND –0.3 — 2.8 V Voltage on V with Respect to GND –0.3 — 5.5 V IO Voltage on any Port I/O Pin or RST with Respect to –0.3 — V + 0.3 V IO GND Maximum Total Current throughV or GND — — 500 mA REGIN Maximum Output Current Sunk by RST or any Port Pin — — 100 mA Maximum Output Current Sourced by any Port Pin — — 100 mA Note: Stresses outside of the range of the “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the devices at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. Rev. 1.2 40

C8051F50x/F51x 5.2. Electrical Characteristics Table 5.2. Global Electrical Characteristics –40 to +125 °C, 24 MHz system clock unless otherwise specified. Parameter Conditions Min Typ Max Units Supply Input Voltage (V ) 1.8 — 5.25 V REGIN Digital Supply Voltage (VDD) System Clock < 25 MHz VRST1 — 2.75 V 2 2.75 System Clock > 25 MHz Analog Supply Voltage (VDDA) System Clock < 25 MHz V 1 — 2.75 RST V 2 2.75 (Must be connected to V ) System Clock > 25 MHz DD Digital Supply RAM Data 1.5 Retention Voltage Port I/O Supply Voltage (VIO) Normal Operation 1.82 — 5.25 V SYSCLK (System Clock)3 0 — 50 MHz T (SYSCLK High Time) 9 — — ns SYSH T (SYSCLK Low Time) 9 — — ns SYSL Specified Operating –40 — +125 °C Temperature Range Digital Supply Current—CPU Active (Normal Mode, fetching instructions from Flash) IDD4 VDD = 2.1 V, F = 200 kHz — 95 — µA V = 2.1 V, F = 1.5 MHz — 700 — µA DD V = 2.1 V, F = 25 MHz — 10 11 mA DD V = 2.1 V, F = 50 MHz — 19 21 mA DD Notes: 1. Given in Table 5.4 on page 46. 2. V should not be lower than the V voltage. IO DD 3. SYSCLK must be at least 32 kHz to enable debugging. 4. Based on device characterization data; Not production tested. Does not include oscillator supply current. 5. IDD can be estimated for frequencies < 12.5 MHz by simply multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate I for >12.5 MHz, the DD estimate should be the current at 50 MHz minus the difference in current indicated by the frequency sensitivity number. For example: V = 2.6 V; F = 20 MHz, I = 26 mA - (50 MHz - DD DD 20 MHz) * 0.48 mA/MHz = 11.6 mA. 6. Idle IDD can be estimated for frequencies < 1 MHz by simply multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate Idle I for >1 MHz, the DD estimate should be the current at 50 MHz minus the difference in current indicated by the frequency sensitivity number. For example: V = 2.6 V; F = 5 MHz, Idle I = 21 mA – (50 MHz – 5 MHz) x 0.41 mA/MHz = 2.6 mA. DD DD 41 Rev. 1.2

C8051F50x/F51x Table 5.2. Global Electrical Characteristics (Continued) –40 to +125 °C, 24 MHz system clock unless otherwise specified. Parameter Conditions Min Typ Max Units IDD4 VDD = 2.6 V, F = 200 kHz — 130 — µA V = 2.6 V, F = 1.5 MHz — 990 — µA DD V = 2.6 V, F = 25 MHz — 14 21 mA DD V = 2.6 V, F = 50 MHz — 25 33 mA DD I Supply Sensitivity4 F = 25 MHz — 68 — %/V DD F = 1 MHz — 73 — %/V IDD Frequency Sensitivity 4,5 VDD = 2.1V, F < 12.5 MHz, T = 25 °C — 0.46 — mA/MHz VDD = 2.1V, F > 12.5 MHz, T = 25 °C — 0.36 — mA/MHz VDD = 2.6V, F < 12.5 MHz, T = 25 °C — 0.64 — mA/MHz VDD = 2.6V, F > 12.5 MHz, T = 25 °C — 0.47 — mA/MHz Notes: 1. Given in Table 5.4 on page 46. 2. V should not be lower than the V voltage. IO DD 3. SYSCLK must be at least 32 kHz to enable debugging. 4. Based on device characterization data; Not production tested. Does not include oscillator supply current. 5. IDD can be estimated for frequencies < 12.5 MHz by simply multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate I for >12.5 MHz, the DD estimate should be the current at 50 MHz minus the difference in current indicated by the frequency sensitivity number. For example: V = 2.6 V; F = 20 MHz, I = 26 mA - (50 MHz - DD DD 20 MHz) * 0.48 mA/MHz = 11.6 mA. 6. Idle IDD can be estimated for frequencies < 1 MHz by simply multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate Idle I for >1 MHz, the DD estimate should be the current at 50 MHz minus the difference in current indicated by the frequency sensitivity number. For example: V = 2.6 V; F = 5 MHz, Idle I = 21 mA – (50 MHz – 5 MHz) x 0.41 mA/MHz = 2.6 mA. DD DD Rev. 1.2 42

C8051F50x/F51x Table 5.2. Global Electrical Characteristics (Continued) –40 to +125 °C, 24 MHz system clock unless otherwise specified. Parameter Conditions Min Typ Max Units Digital Supply Current—CPU Inactive (Idle Mode, not fetching instructions from Flash) IDD4 VDD = 2.1 V, F = 200 kHz — 60 — µA V = 2.1 V, F = 1.5 MHz — 460 — µA DD V = 2.1 V, F = 25 MHz — 7.2 8.0 mA DD V = 2.1 V, F = 50 MHz — 14 16 mA DD IDD4 VDD = 2.6 V, F = 200 kHz — 75 — µA V = 2.6 V, F = 1.5 MHz — 600 — µA DD V = 2.6 V, F = 25 MHz — 9.3 15 mA DD V = 2.6 V, F = 50 MHz — 19 25 mA DD I Supply Sensitivity4 F = 25 MHz — 57 — DD %/V F = 1 MHz — 56 — IDD Frequency Sensitivity 4.6 VDD = 2.1V, F < 12.5 MHz, T = 25 °C — 0.29 — VDD = 2.1V, F > 12.5 MHz, T = 25 °C — 0.29 — mA/MHz VDD = 2.6V, F < 12.5 MHz, T = 25 °C — 0.38 — VDD = 2.6V, F > 12.5 MHz, T = 25 °C — 0.38 — Digital Supply Current4 Oscillator not running, (Stop or Suspend Mode) VDD Monitor Disabled Temp = 25 °C — 2 — µA Temp = 60 °C — 10 — Temp= 125 °C — 120 — Notes: 1. Given in Table 5.4 on page 46. 2. V should not be lower than the V voltage. IO DD 3. SYSCLK must be at least 32 kHz to enable debugging. 4. Based on device characterization data; Not production tested. Does not include oscillator supply current. 5. IDD can be estimated for frequencies < 12.5 MHz by simply multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate I for >12.5 MHz, the DD estimate should be the current at 50 MHz minus the difference in current indicated by the frequency sensitivity number. For example: V = 2.6 V; F = 20 MHz, I = 26 mA - (50 MHz - DD DD 20 MHz) * 0.48 mA/MHz = 11.6 mA. 6. Idle IDD can be estimated for frequencies < 1 MHz by simply multiplying the frequency of interest by the frequency sensitivity number for that range. When using these numbers to estimate Idle I for >1 MHz, the DD estimate should be the current at 50 MHz minus the difference in current indicated by the frequency sensitivity number. For example: V = 2.6 V; F = 5 MHz, Idle I = 21 mA – (50 MHz – 5 MHz) x 0.41 mA/MHz = 2.6 mA. DD DD 43 Rev. 1.2

C8051F50x/F51x Figure 5.1. Minimum VDD Monitor Threshold vs. System Clock Frequency Note: With system clock frequencies greater than 25 MHz, the VDD monitor level should be set to the high threshold (VDMLVL = 1b in SFR VDM0CN) to prevent undefined CPU operation. The high threshold should only be used with an external regulator powering VDD directly. See Figure 10.2 on page 85 for the recommended power supply connections. Rev. 1.2 44

C8051F50x/F51x Table 5.3. Port I/O DC Electrical Characteristics V = 1.8 to 2.75 V, –40 to +125 °C unless otherwise specified. DD Parameters Conditions Min Typ Max Units Output High I = –3 mA, Port I/O push-pull V – 0.4 — — V OH IO Voltage I = –10 µA, Port I/O push-pull V – 0.02 — — OH IO I = –10 mA, Port I/O push-pull — V – 0.7 — OH IO Output Low V = 1.8 V: IO Voltage I = 70 µA — — 50 OL I = 8.5 mA — — 750 OL V = 2.7 V: IO I = 70 µA — — 45 mV OL I = 8.5 mA — — 550 OL V = 5.25 V: IO I = 70 µA — — 40 OL I = 8.5 mA — — 400 OL Input High V = 5.25 V 0.7 x VIO — — V Voltage REGIN Input Low Volt- V = 2.7 V — — 0.3 x VIO V age REGIN Weak Pullup Off — — 2 Weak Pullup On, V = 2.1 V, IO VIN = 0 V, VDD = 1.8 V — 6 9 Input Leakage Weak Pullup On, V = 2.6 V, µA Current IO VIN = 0 V, VDD = 2.6 V — 15 22 Weak Pullup On, V = 5.0 V, IO VIN = 0 V, VDD = 2.6 V — 47 115 45 Rev. 1.2

C8051F50x/F51x Table 5.4. Reset Electrical Characteristics –40 to +125 °C unless otherwise specified. Parameter Conditions Min Typ Max Units RST Output Low Voltage VIO = 5 V; IOL = 70 µA — — 40 mV RST Input High Voltage 0.7 x V — — IO RST Input Low Voltage — — 0.3 x V IO RST Input Pullup Current RST = 0.0 V, VIO = 5 V — 47 115 µA V RST Threshold (V ) 1.65 1.75 1.80 V DD RST-LOW V RST Threshold (V ) 2.25 2.30 2.45 V DD RST-HIGH Time from last system clock rising edge to reset initiation Missing Clock Detector Timeout µs VDD = 2.1V 200 370 600 VDD = 2.5V 200 270 600 Delay between release of Reset Time Delay any reset source and code — 130 160 µs execution at location 0x0000 Minimum RST Low Time to 6 — — µs Generate a System Reset V Monitor Turn-on Time — 60 100 µs DD V Monitor Supply Current — 1 2 µA DD Table 5.5. Flash Electrical Characteristics V = 1.8 to 2.75 V, –40 to +125 °C unless otherwise specified. DD Parameter Conditions Min Typ Max Units C8051F500/1/2/3/8/9 65536* Flash Size Bytes C8051F504/5/6/7-F510/1 32768 Endurance 20 k 150 k — Erase/Write Flash Retention 85 °C 10 — — Years Erase Cycle Time 25 MHz System Clock 28 30 45 ms Write Cycle Time 25 MHz System Clock 79 84 125 µs VDD Write / Erase operations VRST-HIGH2 — — V 1. On the 64K Flash devices, 1024 bytes at addresses 0xFC00 to 0xFFFF are reserved. 2. See Table 5.4 for the V specification. RST-HIGH Rev. 1.2 46

C8051F50x/F51x Table 5.6. Internal High-Frequency Oscillator Electrical Characteristics V = 1.8 to 2.75 V, –40 to +125 °C unless otherwise specified; Using factory-calibrated settings. DD Parameter Conditions Min Typ Max Units Oscillator Frequency IFCN = 111b; 24 – 0.5% 242 24 + 0.5% MHz VDD > VREGMIN1 IFCN = 111b; 24 – 1.0% 242 24 + 1.0% VDD < VREGMIN1 Oscillator Supply Current Internal Oscillator On — 830 1300 µA (from V ) OSCICN[7:6] = 11b DD Internal Oscillator Suspend Temp = 25 °C — 66 — µA OSCICN[7:6] = 00b Temp = 85 °C — 110 — ZTCEN = 1 Temp = 125 °C — 190 — Wake-up Time From Suspend OSCICN[7:6] = 00b — 1 — µs Power Supply Sensitivity Constant Temperature — 0.10 — %/V Temperature Sensitivity3 Constant Supply TC — 5.0 — ppm/°C 1 TC — –0.65 — ppm/°C2 2 1. VREGMIN is the minimum output of the voltage regulator for its low setting (REG0CN: REG0MD = 0b). See Table 5.8, “Voltage Regulator Electrical Characteristics,” on page 48. 2. This is the average frequency across the operating temperature range. 3. Use temperature coefficients TC and TC to calculate the new internal oscillator frequency using the 1 2 following equation: f(T) = f0 x (1 + TC x (T – T0) + TC x (T – T0)2) 1 2 where f0 is the internal oscillator frequency at 25 °C and T0 is 25 °C. 47 Rev. 1.2

C8051F50x/F51x Table 5.7. Clock Multiplier Electrical Specifications V = 1.8 to 2.75 V, –40 to +125 °C unless otherwise specified. DD Parameter Conditions Min Typ Max Units Input Frequency (Fcm ) 2 — — MHz in Output Frequency — — 50 MHz Power Supply Current — 1.1 1.9 mA Table 5.8. Voltage Regulator Electrical Characteristics V = 1.8 to 2.75 V, –40 to +125 °C unless otherwise specified. DD Parameter Conditions Min Typ Max Units Input Voltage Range (V )* 1.8* 5.25 V REGIN Dropout Voltage (V ) Maximum Current = 50 mA — 10 — mV/mA DO 2.1 V operation (REG0MD = 0) 2.0 2.1 2.25 Output Voltage (V ) V DD 2.6 V operation (REG0MD = 1) 2.5 2.6 2.75 Bias Current — 1 9 µA Dropout Indicator Detection With respect to VDD –0.21 — –0.02 V Threshold Output Voltage Temperature — 0.11 — mV/°C Coefficient 50 mA load with V = 2.4 V REGIN VREG Settling Time — 450 — µs and V load capacitor of 4.8 µF DD *Note: The minimum input voltage is 1.8 V or V + V (max load), whichever is greater DD DO Rev. 1.2 48

C8051F50x/F51x Table 5.9. ADC0 Electrical Characteristics VDDA = 1.8 to 2.75 V, –40 to +125 °C, VREF = 1.5 V (REFSL=0) unless otherwise specified. Parameter Conditions Min Typ Max Units DC Accuracy Resolution 12 bits Integral Nonlinearity — ±0.5 ±3 LSB Differential Nonlinearity Guaranteed Monotonic — ±0.5 ±1 LSB Offset Error1 –10 –1.8 10 LSB Full Scale Error –20 1.7 20 LSB Offset Temperature Coefficient — –2 — ppm/°C Dynamic performance (10 kHz sine-wave single-ended input, 1 dB below Full Scale, 200 ksps) Signal-to-Noise Plus Distortion 63 66 — dB Total Harmonic Distortion Up to the 5th harmonic — 82 — dB Spurious-Free Dynamic Range — –84 — dB Conversion Rate SAR Conversion Clock — — 3.6 MHz Conversion Time in SAR Clocks2 13 — — clocks VDDA > 2.0 V 1.5 — — µs Track/Hold Acquisition Time3 VDDA < 2.0 V 3.5 Throughput Rate4 VDDA > 2.0 V — — 200 ksps Analog Inputs gain = 1.0 (default) 0 — VREF V ADC Input Voltage Range5 gain = n 0 VREF/n Absolute Pin Voltage with 0 — V V IO Respect to GND Sampling Capacitance — 32 — pF Input Multiplexer Impedance — 3 — kΩ Power Specifications Power Supply Current Operating Mode, 200 ksps — 1100 1500 µA (VDDA supplied to ADC0) Burst Mode (Idle) — 1100 1500 µA Power-On Time 5 — — µs Power Supply Rejection Ratio — -60 — dB Notes: 1. Represents one standard deviation from the mean. Offset and full-scale error can be removed through calibration. 2. An additional 2 FCLK cycles are required to start and complete a conversion 3. Additional tracking time may be required depending on the output impedance connected to the ADC input. See Section “6.2.1. Settling Time Requirements” on page 57. 4. An increase in tracking time will decrease the ADC throughput. 5. See Section “6.3. Selectable Gain” on page 58 for more information about the setting the gain. 49 Rev. 1.2

C8051F50x/F51x Table 5.10. Temperature Sensor Electrical Characteristics VDDA = 1.8 to 2.75 V, –40 to +125 °C unless otherwise specified. Parameter Conditions Min Typ Max Units Linearity — ±0.1 — °C Slope — 3.33 — mV/°C Slope Error* — ±100 — µV/°C Offset Temp = 0 °C — 856 — mV Offset Error* Temp = 0 °C — ±14 — mV Power Supply Current — 21 — µA Tracking Time 12 — — µs *Note: Represents one standard deviation from the mean. Table 5.11. Voltage Reference Electrical Characteristics VDDA = 1.8 to 2.75 V, –40 to +125 °C unless otherwise specified. Parameter Conditions Min Typ Max Units Internal Reference (REFBE = 1) Output Voltage 25 °C ambient (REFLV = 0) 1.45 1.50 1.55 V 25 °C ambient (REFLV = 1), V = 2.6 V 2.15 2.20 2.25 DD VREF Short-Circuit Current — 5 10 mA VREF Temperature — 33 — ppm/°C Coefficient Power Consumption Internal — 30 50 µA Load Regulation Load = 0 to 200 µA to AGND — 3 — µV/µA VREF Turn-on Time 1 4.7 µF and 0.1 µF bypass — 1.5 — ms VREF Turn-on Time 2 0.1 µF bypass — 46 — µs Power Supply Rejection — 1.3 — mV/V External Reference (REFBE = 0) Input Voltage Range 1.5 — V V DDA Input Current Sample Rate = 200 ksps; VREF = 1.5 V — 2.2 — µA Power Specifications Reference Bias Generator REFBE = 1 or TEMPE = 1 — 21 40 µA Rev. 1.2 50

C8051F50x/F51x Table 5.12. Comparator 0 and Comparator 1 Electrical Characteristics VIO = 1.8 to 5.125 V, –40 to +125 °C unless otherwise noted. Parameter Conditions Min Typ Max Units Response Time: CPn+ – CPn– = 100 mV — 310 — ns Mode 0, Vcm* = 1.5 V CPn+ – CPn– = –100 mV — 340 — ns Response Time: CPn+ – CPn– = 100 mV — 410 — ns Mode 1, Vcm* = 1.5 V CPn+ – CPn– = –100 mV — 510 — ns Response Time: CPn+ – CPn– = 100 mV — 480 — ns Mode 2, Vcm* = 1.5 V CP0+ – CP0– = –100 mV — 620 — ns Response Time: CPn+ – CPn– = 100 mV — 1600 — ns Mode 3, Vcm* = 1.5 V CPn+ – CPn– = –100 mV — 2600 — ns Common-Mode Rejection Ratio — 1.7 8.9 mV/V Positive Hysteresis 1 CPnHYP1–0 = 00 -2 0 2 mV Positive Hysteresis 2 CPnHYP1–0 = 01 2 6 10 mV Positive Hysteresis 3 CPnHYP1–0 = 10 5 11 20 mV Positive Hysteresis 4 CPnHYP1–0 = 11 13 21 40 mV Negative Hysteresis 1 CPnHYN1–0 = 00 -2 0 2 mV Negative Hysteresis 2 CPnHYN1–0 = 01 2 6 10 mV Negative Hysteresis 3 CPnHYN1–0 = 10 5 11 20 mV Negative Hysteresis 4 CPnHYN1–0 = 11 13 21 40 mV Inverting or Non-Inverting Input –0.25 — V + 0.25 V IO Voltage Range Input Capacitance — 8 — pF Input Offset Voltage –10 — +10 mV Power Supply Power Supply Rejection — 0.33 — mV/V Power-Up Time — 3 — µs Mode 0 — 6.2 20 µA Mode 1 — 3.8 10 µA Supply Current at DC Mode 2 — 2.6 7.5 µA Mode 3 — 0.6 3 µA *Note: Vcm is the common-mode voltage on CP0+ and CP0–. 51 Rev. 1.2

C8051F50x/F51x 6. 12-Bit ADC (ADC0) The ADC0 on the C8051F50x/F51x consists of an analog multiplexer (AMUX0) with 35/28 total input selec- tions and a 200 ksps, 12-bit successive-approximation-register (SAR) ADC with integrated track-and-hold, programmable window detector, programmable attenuation (1:2), and hardware accumulator. The ADC0 subsystem has a special Burst Mode which can automatically enable ADC0, capture and accumulate sam- ples, then place ADC0 in a low power shutdown mode without CPU intervention. The AMUX0, data con- version modes, and window detector are all configurable under software control via the Special Function Registers shows in Figure 6.1. ADC0 inputs are single-ended and may be configured to measure P0.0- P3.7, the Temperature Sensor output, V , or GND with respect to GND. The voltage reference for ADC0 DD is selected as described in Section “7. Temperature Sensor” on page 72. ADC0 is enabled when the AD0EN bit in the ADC0 Control register (ADC0CN) is set to logic 1, or when performing conversions in Burst Mode. ADC0 is in low power shutdown when AD0EN is logic 0 and no Burst Mode conversions are taking place. ADC0MX ADC0TK ADC0CN *Available on 48-pin and ADC0MX4ADC0MX3ADC0MX2ADC0MX1ADC0MX0 AD0PWR3AD0PWR2AD0PWR1AD0PWR0AD0TM1AD0TM0AD0TK1AD0TK0 AD0ENBURSTENAD0INTAD0BUSYAD0WINTAD0LJSTAD0CM1AD0CM0 40-pin packages 00 AD0BUSY (W) P0.0 Start VDD Start Conversion 01 Timer 1 Overflow Conversion SYSCLK Burst Mode 10 CNVSTR Input Logic P0.7 11 Timer 2 Overflow P1.0 Burst Mode LK Oscillator C 25 MHz Max F 0L 12-Bit C D A P1.7 SAR Selectable P2.0 Gain Accumulator 35-to-1 ADC H AMUX0 C0 D P2.7 A P3.0 ADC0GNH ADC0GNL ADC0GNA 0ETKF P3.1* M1:PROSCLRE D0TAD0D0PF AD0WINT A A P3.7* Window Compare TempGV SNDeDDnsor AD0SC4AD0SC3AD0SC2AD0SC1AD0SC0AD0RPT1AD0RPT0GAINEN ADC0LTH ADC0LTL 32 Logic ADC0CF ADC0GTH ADC0GTL Figure 6.1. ADC0 Functional Block Diagram Rev. 1.2 52

C8051F50x/F51x 6.1. Modes of Operation In a typical system, ADC0 is configured using the following steps: 1. If a gain adjustment is required, refer to Section “6.3. Selectable Gain” on page 58. 2. Choose the start of conversion source. 3. Choose Normal Mode or Burst Mode operation. 4. If Burst Mode, choose the ADC0 Idle Power State and set the Power-Up Time. 5. Choose the tracking mode. Note that Pre-Tracking Mode can only be used with Normal Mode. 6. Calculate the required settling time and set the post convert-start tracking time using the AD0TK bits. 7. Choose the repeat count. 8. Choose the output word justification (Right-Justified or Left-Justified). 9. Enable or disable the End of Conversion and Window Comparator Interrupts. 6.1.1. Starting a Conversion A conversion can be initiated in one of four ways, depending on the programmed states of the ADC0 Start of Conversion Mode bits (AD0CM1–0) in register ADC0CN. Conversions may be initiated by one of the fol- lowing:  Writing a 1 to the AD0BUSY bit of register ADC0CN  A rising edge on the CNVSTR input signal (pin P0.1)  A Timer 1 overflow (i.e., timed continuous conversions)  A Timer 2 overflow (i.e., timed continuous conversions) Writing a 1 to AD0BUSY provides software control of ADC0 whereby conversions are performed "on- demand.” During conversion, the AD0BUSY bit is set to logic 1 and reset to logic 0 when the conversion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the ADC0 interrupt flag (AD0INT). Note: When polling for ADC conversion completions, the ADC0 interrupt flag (AD0INT) should be used. Converted data is available in the ADC0 data registers, ADC0H:ADC0L, when bit AD0INT is logic 1. Note that when Timer 2 overflows are used as the conversion source, Low Byte overflows are used if Timer2 is in 8-bit mode; High byte overflows are used if Timer 2 is in 16-bit mode. See Section “26. Timers” on page 265 for timer configuration. Important Note About Using CNVSTR: The CNVSTR input pin also functions as Port pin P0.1. When the CNVSTR input is used as the ADC0 conversion source, Port pin P0.1 should be skipped by the Digital Crossbar. To configure the Crossbar to skip P0.1, set to 1 Bit1 in register P0SKIP. See Section “20. Port Input/Output” on page 177 for details on Port I/O configuration. 6.1.2. Tracking Modes Each ADC0 conversion must be preceded by a minimum tracking time for the converted result to be accu- rate. ADC0 has three tracking modes: Pre-Tracking, Post-Tracking, and Dual-Tracking. Pre-Tracking Mode provides the minimum delay between the convert start signal and end of conversion by tracking continu- ously before the convert start signal. This mode requires software management in order to meet minimum tracking requirements. In Post-Tracking Mode, a programmable tracking time starts after the convert start signal and is managed by hardware. Dual-Tracking Mode maximizes tracking time by tracking before and after the convert start signal. Figure 6.2 shows examples of the three tracking modes. Pre-Tracking Mode is selected when AD0TM is set to 10b. Conversions are started immediately following the convert start signal. ADC0 is tracking continuously when not performing a conversion. Software must allow at least the minimum tracking time between each end of conversion and the next convert start signal. The minimum tracking time must also be met prior to the first convert start signal after ADC0 is enabled. 53 Rev. 1.2

C8051F50x/F51x Post-Tracking Mode is selected when AD0TM is set to 01b. A programmable tracking time based on AD0TK is started immediately following the convert start signal. Conversions are started after the pro- grammed tracking time ends. After a conversion is complete, ADC0 does not track the input. Rather, the sampling capacitor remains disconnected from the input making the input pin high-impedance until the next convert start signal. Dual-Tracking Mode is selected when AD0TM is set to 11b. A programmable tracking time based on AD0TK is started immediately following the convert start signal. Conversions are started after the pro- grammed tracking time ends. After a conversion is complete, ADC0 tracks continuously until the next con- version is started. Depending on the output connected to the ADC input, additional tracking time, more than is specified in Table 5.9, may be required after changing MUX settings. See the settling time requirements described in Section “6.2.1. Settling Time Requirements” on page 57. Convert Start Pre-Tracking Track Convert Track Convert ... AD0TM = 10 Post-Tracking Idle Track Convert Idle Track Convert.. AD0TM= 01 Dual-Tracking Track Track Convert Track Track Convert.. AD0TM = 11 Figure 6.2. ADC0 Tracking Modes 6.1.3. Timing ADC0 has a maximum conversion speed specified in Table 5.9. ADC0 is clocked from the ADC0 Subsys- tem Clock (FCLK). The source of FCLK is selected based on the BURSTEN bit. When BURSTEN is logic 0, FCLK is derived from the current system clock. When BURSTEN is logic 1, FCLK is derived from the Burst Mode Oscillator, an independent clock source with a maximum frequency of 25 MHz. When ADC0 is performing a conversion, it requires a clock source that is typically slower than FCLK. The ADC0 SAR conversion clock (SAR clock) is a divided version of FCLK. The divide ratio can be configured using the AD0SC bits in the ADC0CF register. The maximum SAR clock frequency is listed in Table 5.9. ADC0 can be in one of three states at any given time: tracking, converting, or idle. Tracking time depends on the tracking mode selected. For Pre-Tracking Mode, tracking is managed by software and ADC0 starts conversions immediately following the convert start signal. For Post-Tracking and Dual-Tracking Modes, the tracking time after the convert start signal is equal to the value determined by the AD0TK bits plus 2 FCLK cycles. Tracking is immediately followed by a conversion. The ADC0 conversion time is always 13 SAR clock cycles plus an additional 2 FCLK cycles to start and complete a conversion. Figure 6.3 shows timing diagrams for a conversion in Pre-Tracking Mode and tracking plus conversion in Post-Tracking or Dual-Tracking Mode. In this example, repeat count is set to one. Rev. 1.2 54

C8051F50x/F51x Convert Start Pre-Tracking Mode Time F S1 S2 ... S12 S13 F ADC0 State Convert AD0INT Flag Post-Tracking or Dual-Tracking Modes (AD0TK = ‘00') Time F S1 S2 F F S1 S2 ... S12 S13 F ADC0 State Track Convert AD0INT Flag Key F Equal to one period of FCLK. Sn Each Sn is equal to one period of the SAR clock. Figure 6.3. 12-Bit ADC Tracking Mode Example 6.1.4. Burst Mode Burst Mode is a power saving feature that allows ADC0 to remain in a very low power state between con- versions. When Burst Mode is enabled, ADC0 wakes from a very low power state, accumulates 1, 4, 8, or 16 samples using an internal Burst Mode clock (approximately 25 MHz), then re-enters a very low power state. Since the Burst Mode clock is independent of the system clock, ADC0 can perform multiple conver- sions then enter a very low power state within a single system clock cycle, even if the system clock is slow (e.g., 32.768 kHz), or suspended. Burst Mode is enabled by setting BURSTEN to logic 1. When in Burst Mode, AD0EN controls the ADC0 idle power state (i.e. the state ADC0 enters when not tracking or performing conversions). If AD0EN is set to logic 0, ADC0 is powered down after each burst. If AD0EN is set to logic 1, ADC0 remains enabled after each burst. On each convert start signal, ADC0 is awakened from its Idle Power State. If ADC0 is powered down, it will automatically power up and wait the programmable Power-Up Time controlled by the AD0PWR bits. Otherwise, ADC0 will start tracking and converting immediately. Figure 6.4 shows an exam- ple of Burst Mode Operation with a slow system clock and a repeat count of 4. Important Note: When Burst Mode is enabled, only Post-Tracking and Dual-Tracking modes can be used. When Burst Mode is enabled, a single convert start will initiate a number of conversions equal to the repeat count. When Burst Mode is disabled, a convert start is required to initiate each conversion. In both modes, the ADC0 End of Conversion Interrupt Flag (AD0INT) will be set after “repeat count” conversions have 55 Rev. 1.2

C8051F50x/F51x been accumulated. Similarly, the Window Comparator will not compare the result to the greater-than and less-than registers until “repeat count” conversions have been accumulated. Note: When using Burst Mode, care must be taken to issue a convert start signal no faster than once every four SYSCLK periods. This includes external convert start signals. System Clock Convert Start (AD0BUSY or Timer Overflow) Post-Tracking Powered Power-Up Powered Power-Up AD0TM = 01 T C T C T C T C T C.. Down and Idle Down and Idle AD0EN = 0 Dual-Tracking Powered Power-Up Powered Power-Up AD0TM = 11 T C T C T C T C T C.. Down and Track Down and Track AD0EN = 0 AD0PWR Post-Tracking AD0TM = 01 Idle T C T C T C T C Idle T C T C T C.. AD0EN = 1 Dual-Tracking AD0TM = 11 Track T C T C T C T C Track T C T C T C.. AD0EN = 1 T = Tracking C = Converting Convert Start (CNVSTR) Post-Tracking Powered Power-Up Powered Power-Up AD0TM = 01 T C T C.. Down and Idle Down and Idle AD0EN = 0 Dual-Tracking Powered Power-Up Powered Power-Up AD0TM = 11 T C T C.. Down and Track Down and Track AD0EN = 0 AD0PWR Post-Tracking AD0TM = 01 Idle T C Idle T C Idle.. AD0EN = 1 Dual-Tracking AD0TM = 11 Track T C Track T C Track.. AD0EN = 1 T = Tracking C = Converting Figure 6.4. 12-Bit ADC Burst Mode Example With Repeat Count Set to 4 Rev. 1.2 56

C8051F50x/F51x 6.2. Output Code Formatting The registers ADC0H and ADC0L contain the high and low bytes of the output conversion code. When the repeat count is set to 1, conversion codes are represented in 12-bit unsigned integer format and the output conversion code is updated after each conversion. Inputs are measured from 0 to V x 4095/4096. Data REF can be right-justified or left-justified, depending on the setting of the AD0LJST bit (ADC0CN.2). Unused bits in the ADC0H and ADC0L registers are set to 0. Example codes are shown below for both right-justi- fied and left-justified data. Input Voltage Right-Justified ADC0H:ADC0L Left-Justified ADC0H:ADC0L (AD0LJST = 0) (AD0LJST = 1) VREF x 4095/4096 0x0FFF 0xFFF0 VREF x 2048/4096 0x0800 0x8000 VREF x 2047/4096 0x07FF 0x7FF0 0 0x0000 0x0000 When the ADC0 Repeat Count is greater than 1, the output conversion code represents the accumulated result of the conversions performed and is updated after the last conversion in the series is finished. Sets of 4, 8, or 16 consecutive samples can be accumulated and represented in unsigned integer format. The repeat count can be selected using the AD0RPT bits in the ADC0CF register. The value must be right-jus- tified (AD0LJST = 0), and unused bits in the ADC0H and ADC0L registers are set to 0. The following example shows right-justified codes for repeat counts greater than 1. Notice that accumulating 2n samples is equivalent to left-shifting by n bit positions when all samples returned from the ADC have the same value. Input Voltage Repeat Count = 4 Repeat Count = 8 Repeat Count = 16 V x 4095/4096 0x3FFC 0x7FF8 0xFFF0 REF V x 2048/4096 0x2000 0x4000 0x8000 REF V x 2047/4096 0x1FFC 0x3FF8 0x7FF0 REF 0 0x0000 0x0000 0x0000 6.2.1. Settling Time Requirements A minimum tracking time is required before an accurate conversion is performed. This tracking time is determined by any series impedance, including the AMUX0 resistance, the ADC0 sampling capacitance, and the accuracy required for the conversion. Figure 6.5 shows the equivalent ADC0 input circuit. The required ADC0 settling time for a given settling accuracy (SA) may be approximated by Equation 6.1. When measuring the Temperature Sensor output, use the settling time specified in Table 5.10 on page 50. When measuring V with respect to GND, R DD TO- reduces to R . See Table 5.9 for ADC0 minimum settling time requirements as well as the mux TAL MUX impedance and sampling capacitor values. n t = ln--2------ × R C SA TOTAL SAMPLE Equation 6.1. ADC0 Settling Time Requirements Where: SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB) t is the required settling time in seconds R is the sum of the AMUX0 resistance and any external source resistance. TOTAL n is the ADC resolution in bits (10). 57 Rev. 1.2

C8051F50x/F51x M U X Select Px.x R MUX C SAMPLE R C = R * C Input MUX SAMPLE Figure 6.5. ADC0 Equivalent Input Circuit 6.3. Selectable Gain ADC0 on the C8051F50x/F51x family of devices implements a selectable gain adjustment option. By writ- ing a value to the gain adjust address range, the user can select gain values between 0 and 1.016. For example, three analog sources to be measured have full-scale outputs of 5.0 V, 4.0 V, and 3.0 V, respectively. Each ADC measurement would ideally use the full dynamic range of the ADC with an internal voltage reference of 1.5 V or 2.2 V (set to 2.2 V for this example). When selecting the first source (5.0 V full-scale), a gain value of 0.44 (5 V full scale x 0.44 = 2.2 V full scale) provides a full-scale signal of 2.2 V when the input signal is 5.0 V. Likewise, a gain value of 0.55 (4 V full scale x 0.55 = 2.2 V full scale) for the second source and 0.73 (3 V full scale x 0.73 = 2.2 V full scale) for the third source provide full-scale ADC0 measurements when the input signal is full-scale. Additionally, some sensors or other input sources have small part-to-part variations that must be accounted for to achieve accurate results. In this case, the programmable gain value could be used as a calibration value to eliminate these part-to-part variations. 6.3.1. Calculating the Gain Value The ADC0 selectable gain feature is controlled by 13 bits in three registers. ADC0GNH contains the 8 upper bits of the gain value and ADC0GNL contains the 4 lower bits of the gain value. The final GAINADD bit (ADC0GNA.0) controls an optional extra 1/64 (0.016) of gain that can be added in addition to the ADC0GNH and ADC0GNL gain. The ADC0GNA.0 bit is set to 1 after a power-on reset. The equivalent gain for the ADC0GNH, ADC0GNL and ADC0GNA registers is as follows: gain = G------A----I--N--- + GAINADD× --1----  4096  64 Equation 6.2. Equivalent Gain from the ADC0GNH and ADC0GNL Registers Where: GAIN is the 12-bit word of ADC0GNH[7:0] and ADC0GNL[7:4] GAINADD is the value of the GAINADD bit (ADC0GNA.0) gain is the equivalent gain value from 0 to 1.016 Rev. 1.2 58

C8051F50x/F51x For example, if ADC0GNH = 0xFC, ADC0GNL = 0x00, and GAINADD = 1, GAIN = 0xFC0 = 4032, and the resulting equation is as follows: GAIN = 4----0---3----2-- +1×--1---- = 0.984+ 0.016 = 1.0 4096 64 The table below equates values in the ADC0GNH, ADC0GNL, and ADC0GNA registers to the equivalent gain using this equation. ADC0GNH Value ADC0GNL Value GAINADD Value GAIN Value Equivalent Gain 0xFC (default) 0x00 (default) 1 (default) 4032 + 64 1.0 (default) 0x7C 0x00 1 1984 + 64 0.5 0xBC 0x00 1 3008 + 64 0.75 0x3C 0x00 1 960 + 64 0.25 0xFF 0xF0 0 4095 + 0 ~1.0 0xFF 0xF0 1 4096 + 64 1.016 For any desired gain value, the GAIN registers can be calculated by the following: GAIN = gain –GAINADD× --1---- × 4096  64 Equation 6.3. Calculating the ADC0GNH and ADC0GNL Values from the Desired Gain Where: GAIN is the 12-bit word of ADC0GNH[7:0] and ADC0GNL[7:4] GAINADD is the value of the GAINADD bit (ADC0GNA.0) gain is the equivalent gain value from 0 to 1.016 When calculating the value of GAIN to load into the ADC0GNH and ADC0GNL registers, the GAINADD bit can be turned on or off to reach a value closer to the desired gain value. For example, the initial example in this section requires a gain of 0.44 to convert 5 V full scale to 2.2 V full scale. Using Equation 6.3: GAIN = 0.44–GAINADD× --1---- ×4096  64 If GAINADD is set to 1, this makes the equation: GAIN = 0.44– 1× --1---- ×4096 = 0.424 ×4096 = 1738 = 0x06CA  64 The actual gain from setting GAINADD to 1 and ADC0GNH and ADC0GNL to 0x6CA is 0.4399. A similar gain can be achieved if GAINADD is set to 0 with a different value for ADC0GNH and ADC0GNL. 59 Rev. 1.2

C8051F50x/F51x 6.3.2. Setting the Gain Value The three programmable gain registers are accessed indirectly using the ADC0H and ADC0L registers when the GAINEN bit (ADC0CF.0) bit is set. ADC0H acts as the address register, and ADC0L is the data register. The programmable gain registers can only be written to and cannot be read. See Gain Register Definition 6.1, Gain Register Definition 6.2, and Gain Register Definition 6.3 for more information. The gain is programmed using the following steps: 1. Set the GAINEN bit (ADC0CF.0) 2. Load the ADC0H with the ADC0GNH, ADC0GNL, or ADC0GNA address. 3. Load ADC0L with the desired value for the selected gain register. 4. Reset the GAINEN bit (ADC0CF.0) Notes: 1. An ADC conversion should not be performed while the GAINEN bit is set. 2. Even with gain enabled, the maximum input voltage must be less than VREGIN and the maximum voltage of the signal after gain must be less than or equal to V . REF In code, changing the value to 0.44 gain from the previous example looks like: // in ‘C’: ADC0CF |= 0x01; // GAINEN = 1 ADC0H = 0x04; // Load the ADC0GNH address ADC0L = 0x6C; // Load the upper byte of 0x6CA to ADC0GNH ADC0H = 0x07; // Load the ADC0GNL address ADC0L = 0xA0; // Load the lower nibble of 0x6CA to ADC0GNL ADC0H = 0x08; // Load the ADC0GNA address ADC0L = 0x01; // Set the GAINADD bit ADC0CF &= ~0x01; // GAINEN = 0 ; in assembly ORL ADC0CF,#01H ; GAINEN = 1 MOV ADC0H,#04H ; Load the ADC0GNH address MOV ADC0L,#06CH ; Load the upper byte of 0x6CA to ADC0GNH MOV ADC0H,#07H ; Load the ADC0GNL address MOV ADC0L,#0A0H ; Load the lower nibble of 0x6CA to ADC0GNL MOV ADC0H,#08H ; Load the ADC0GNA address MOV ADC0L,#01H ; Set the GAINADD bit ANL ADC0CF,#0FEH ; GAINEN = 0 Rev. 1.2 60

C8051F50x/F51x Gain Register Definition 6.1. ADC0GNH: ADC0 Selectable Gain High Byte Bit 7 6 5 4 3 2 1 0 Name GAINH[7:0] Type W Reset 1 1 1 1 1 1 0 0 Indirect Address = 0x04; Bit Name Function 7:0 GAINH[7:0] ADC0 Gain High Byte. See Section 6.3.1 for details on calculating the value for this register. Note: This register is accessed indirectly; See Section 6.3.2 for details for writing this register. Gain Register Definition 6.2. ADC0GNL: ADC0 Selectable Gain Low Byte Bit 7 6 5 4 3 2 1 0 Name GAINL[3:0] Reserved Reserved Reserved Reserved Type W W W W W Reset 0 0 0 0 0 0 0 0 Indirect Address = 0x07; Bit Name Function 7:4 GAINL[3:0] ADC0 Gain Lower 4 Bits. See Figure 6.3.1 for details for setting this register. This register is only accessed indirectly through the ADC0H and ADC0L register. 3:0 Reserved Must Write 0000b Note: This register is accessed indirectly; See Section 6.3.2 for details for writing this register. 61 Rev. 1.2

C8051F50x/F51x Gain Register Definition 6.3. ADC0GNA: ADC0 Additional Selectable Gain Bit 7 6 5 4 3 2 1 0 Name Reserved Reserved Reserved Reserved Reserved Reserved Reserved GAINADD Type W W W W W W W W Reset 0 0 0 0 0 0 0 1 Indirect Address = 0x08; Bit Name Function 7:1 Reserved Must Write 0000000b. 0 GAINADD ADC0 Additional Gain Bit. Setting this bit add 1/64 (0.016) gain to the gain value in the ADC0GNH and ADC0GNL registers. Note: This register is accessed indirectly; See Section 6.3.2 for details for writing this register. Rev. 1.2 62

C8051F50x/F51x SFR Definition 6.4. ADC0CF: ADC0 Configuration Bit 7 6 5 4 3 2 1 0 Name AD0SC[4:0] AD0RPT[1:0] GAINEN Type R/W R/W R/W R/W Reset 1 1 1 1 1 0 0 0 SFR Address = 0xBC; SFR Page = 0x00 Bit Name Function 7:3 AD0SC[4:0] ADC0 SAR Conversion Clock Period Bits. SAR Conversion clock is derived from system clock by the following equation, where AD0SC refers to the 5-bit value held in bits AD0SC4–0. SAR Conversion clock requirements are given in the ADC specification table BURSTEN = 0: FCLK is the current system clock BURSTEN = 1: FLCLK is a maximum of 30 Mhz, independent of the current system clock.. FCLK AD0SC = -------------------- –1 CLK SAR Note: Round up the result of the calculation for AD0SC 2:1 A0RPT[1:0] ADC0 Repeat Count Controls the number of conversions taken and accumulated between ADC0 End of Conversion (ADCINT) and ADC0 Window Comparator (ADCWINT) interrupts. A con- vert start is required for each conversion unless Burst Mode is enabled. In Burst Mode, a single convert start can initiate multiple self-timed conversions. Results in both modes are accumulated in the ADC0H:ADC0L register. When AD0RPT1–0 are set to a value other than '00', the AD0LJST bit in the ADC0CN register must be set to '0' (right justified). 00: 1 conversion is performed. 01: 4 conversions are performed and accumulated. 10: 8 conversions are performed and accumulated. 11: 16 conversions are performed and accumulated. 0 GAINEN Gain Enable Bit. Controls the gain programming. Refer to Section “6.3. Selectable Gain” on page 58 for information about using this bit. 63 Rev. 1.2

C8051F50x/F51x SFR Definition 6.5. ADC0H: ADC0 Data Word MSB Bit 7 6 5 4 3 2 1 0 Name ADC0H[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xBE; SFR Page = 0x00 Bit Name Function 7:0 ADC0H[7:0] ADC0 Data Word High-Order Bits. For AD0LJST = 0 and AD0RPT as follows: 00: Bits 3–0 are the upper 4 bits of the 12-bit result. Bits 7–4 are 0000b. 01: Bits 4–0 are the upper 5 bits of the 14-bit result. Bits 7–5 are 000b. 10: Bits 5–0 are the upper 6 bits of the 15-bit result. Bits 7–6 are 00b. 11: Bits 7–0 are the upper 8 bits of the 16-bit result. For AD0LJST = 1 (AD0RPT must be 00): Bits 7–0 are the most-significant bits of the ADC0 12-bit result. SFR Definition 6.6. ADC0L: ADC0 Data Word LSB Bit 7 6 5 4 3 2 1 0 Name ADC0L[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xBD; SFR Page = 0x00 Bit Name Function 7:0 ADC0L[7:0] ADC0 Data Word Low-Order Bits. For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the ADC0 Accumulated Result. For AD0LJST = 1 (AD0RPT must be '00'): Bits 7–4 are the lower 4 bits of the 12-bit result. Bits 3–0 are 0000b. Rev. 1.2 64

C8051F50x/F51x SFR Definition 6.7. ADC0CN: ADC0 Control Bit 7 6 5 4 3 2 1 0 Name AD0EN BURSTEN AD0INT AD0BUSY AD0WINT AD0LJST AD0CM[1:0] Type R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xE8; SFR Page = 0x00; Bit-Addressable Bit Name Function 7 AD0EN ADC0 Enable Bit. 0: ADC0 Disabled. ADC0 is in low-power shutdown. 1: ADC0 Enabled. ADC0 is active and ready for data conversions. 6 BURSTEN ADC0 Burst Mode Enable Bit. 0: Burst Mode Disabled. 1: Burst Mode Enabled. 5 AD0INT ADC0 Conversion Complete Interrupt Flag. 0: ADC0 has not completed a data conversion since AD0INT was last cleared. 1: ADC0 has completed a data conversion. 4 AD0BUSY ADC0 Busy Bit. Read: Write: 0: ADC0 conversion is not 0: No Effect. in progress. 1: Initiates ADC0 Conver- 1: ADC0 conversion is in sion if AD0CM[1:0] = 00b progress. 3 AD0WINT ADC0 Window Compare Interrupt Flag. This bit must be cleared by software 0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared. 1: ADC0 Window Comparison Data match has occurred. 2 AD0LJST ADC0 Left Justify Select Bit. 0: Data in ADC0H:ADC0L registers is right-justified 1: Data in ADC0H:ADC0L registers is left-justified. This option should not be used with a repeat count greater than 1 (when AD0RPT[1:0] is 01b, 10b, or 11b). 1:0 AD0CM[1:0] ADC0 Start of Conversion Mode Select. 00: ADC0 start-of-conversion source is write of 1 to AD0BUSY. 01: ADC0 start-of-conversion source is overflow of Timer 1. 10: ADC0 start-of-conversion source is rising edge of external CNVSTR. 11: ADC0 start-of-conversion source is overflow of Timer 2. 65 Rev. 1.2

C8051F50x/F51x SFR Definition 6.8. ADC0TK: ADC0 Tracking Mode Select Bit 7 6 5 4 3 2 1 0 Name AD0PWR[3:0] AD0TM[1:0] AD0TK[1:0] Type R/W R/W R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xBA; SFR Page = 0x00; Bit Name Function 7:4 AD0PWR[3:0] ADC0 Burst Power-Up Time. For BURSTEN = 0: ADC0 Power state controlled by AD0EN For BURSTEN = 1, AD0EN = 1: ADC0 remains enabled and does not enter the very low power state For BURSTEN = 1, AD0EN = 0: ADC0 enters the very low power state and is enabled after each convert start signal. The Power-Up time is programmed accord- ing the following equation: Tstartup AD0PWR = ------------------------ –1 or Tstartup = (AD0PWR + 1)200ns 200ns 3:2 AD0TM[1:0] ADC0 Tracking Mode Enable Select Bits. 00: Reserved. 01: ADC0 is configured to Post-Tracking Mode. 10: ADC0 is configured to Pre-Tracking Mode. 11: ADC0 is configured to Dual Tracking Mode. 1:0 AD0TK[1:0] ADC0 Post-Track Time. 00: Post-Tracking time is equal to 2 SAR clock cycles + 2 FCLK cycles. 01: Post-Tracking time is equal to 4 SAR clock cycles + 2 FCLK cycles. 10: Post-Tracking time is equal to 8 SAR clock cycles + 2 FCLK cycles. 11: Post-Tracking time is equal to 16 SAR clock cycles + 2 FCLK cycles. 6.4. Programmable Window Detector The ADC Programmable Window Detector continuously compares the ADC0 output registers to user-pro- grammed limits, and notifies the system when a desired condition is detected. This is especially effective in an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response times. The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used in polled mode. The ADC0 Greater-Than (ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL) registers hold the comparison values. The window detector flag can be programmed to indicate when mea- sured data is inside or outside of the user-programmed limits, depending on the contents of the ADC0 Less-Than and ADC0 Greater-Than registers. Rev. 1.2 66

C8051F50x/F51x SFR Definition 6.9. ADC0GTH: ADC0 Greater-Than Data High Byte Bit 7 6 5 4 3 2 1 0 Name ADC0GTH[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xC4; SFR Page = 0x00 Bit Name Function 7:0 ADC0GTH[7:0] ADC0 Greater-Than Data Word High-Order Bits. SFR Definition 6.10. ADC0GTL: ADC0 Greater-Than Data Low Byte Bit 7 6 5 4 3 2 1 0 Name ADC0GTL[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xC3; SFR Page = 0x00 Bit Name Function 7:0 ADC0GTL[7:0] ADC0 Greater-Than Data Word Low-Order Bits. 67 Rev. 1.2

C8051F50x/F51x SFR Definition 6.11. ADC0LTH: ADC0 Less-Than Data High Byte Bit 7 6 5 4 3 2 1 0 Name ADC0LTH[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xC6; SFR Page = 0x00 Bit Name Function 7:0 ADC0LTH[7:0] ADC0 Less-Than Data Word High-Order Bits. SFR Definition 6.12. ADC0LTL: ADC0 Less-Than Data Low Byte Bit 7 6 5 4 3 2 1 0 Name ADC0LTL[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xC5; SFR Page = 0x00 Bit Name Function 7:0 ADC0LTL[7:0] ADC0 Less-Than Data Word Low-Order Bits. 6.4.1. Window Detector In Single-Ended Mode Figure 6.6 shows two example window comparisons for right-justified data with ADC0LTH:ADC0LTL = 0x0200 (512d) and ADC0GTH:ADC0GTL = 0x0100 (256d). The input voltage can range from 0 to V x (4095/4096) with respect to GND, and is represented by a 12-bit unsigned integer REF value. The repeat count is set to one. In the left example, an AD0WINT interrupt will be generated if the ADC0 conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and ADC0LTH:ADC0LTL (if 0x0100 < ADC0H:ADC0L < 0x0200). In the right example, and AD0WINT interrupt will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT and ADC0LT registers (if ADC0H:ADC0L < 0x0100 or ADC0H:ADC0L > 0x0200). Figure 6.7 shows an exam- ple using left-justified data with the same comparison values. Rev. 1.2 68

C8051F50x/F51x ADC0H:ADC0L ADC0H:ADC0L Input Voltage Input Voltage (Px.x - GND) (Px.x - GND) VREF x (4095/4096) 0x0FFF VREF x (1023/ 0x0FFF 1024) AD0WINT AD0WINT=1 not affected 0x0201 0x0201 VREF x (512/4096) 0x0200 ADC0LTH:ADC0LTL VREF x (512/4096) 0x0200 ADC0GTH:ADC0GTL 0x01FF 0x01FF AD0WINT AD0WINT=1 not affected 0x0101 0x0101 VREF x (256/4096) 0x0100 ADC0GTH:ADC0GTL VREF x (256/4096) 0x0100 ADC0LTH:ADC0LTL 0x00FF 0x00FF AD0WINT AD0WINT=1 not affected 0 0x0000 0 0x0000 Figure 6.6. ADC Window Compare Example: Right-Justified Data ADC0H:ADC0L ADC0H:ADC0L Input Voltage Input Voltage (Px.x - GND) (Px.x - GND) VREF x (4095/4096) 0xFFF0 VREF x (4095/4096) 0xFFF0 AD0WINT AD0WINT=1 not affected 0x2010 0x2010 VREF x (512/4096) 0x2000 ADC0LTH:ADC0LTL VREF x (512/4096) 0x2000 ADC0GTH:ADC0GTL 0x1FF0 0x1FF0 AD0WINT AD0WINT=1 not affected 0x1010 0x1010 VREF x (256/4096) 0x1000 ADC0GTH:ADC0GTL VREF x (256/4096) 0x1000 ADC0LTH:ADC0LTL 0x0FF0 0x0FF0 AD0WINT AD0WINT=1 not affected 0 0x0000 0 0x0000 Figure 6.7. ADC Window Compare Example: Left-Justified Data 69 Rev. 1.2

C8051F50x/F51x 6.5. ADC0 Analog Multiplexer ADC0 includes an analog multiplexer to enable multiple analog input sources. Any of the following may be selected as an input: P0.0–P3.7, the on-chip temperature sensor, the core power supply (V ), or ground DD (GND). ADC0 is single-ended and all signals measured are with respect to GND. The ADC0 input channels are selected using the ADC0MX register as described in SFR Definition 6.13. ADC0MX 5 4 3 2 1 0 X X X X X X M M M M M M 0 0 0 0 0 0 C C C C C C D D D D D D A A A A A A P0.0 P0.7 P1.0 P1.7 P2.0 ADC0 AMUX P2.7 P3.0 P3.7 *P3.1-P3.7 Only available as inputs on 48-pin and 40-pin Temp packages Sensor VDD GND Figure 6.8. ADC0 Multiplexer Block Diagram Important Note About ADC0 Input Configuration: Port pins selected as ADC0 inputs should be config- ured as analog inputs, and should be skipped by the Digital Crossbar. To configure a Port pin for analog input, set to 0 the corresponding bit in register PnMDIN. To force the Crossbar to skip a Port pin, set to 1 the corresponding bit in register PnSKIP. See Section “20. Port Input/Output” on page 177 for more Port I/O configuration details. Rev. 1.2 70

C8051F50x/F51x SFR Definition 6.13. ADC0MX: ADC0 Channel Select Bit 7 6 5 4 3 2 1 0 Name ADC0MX[5:0] Type R R R/W Reset 0 0 1 1 1 1 1 1 SFR Address = 0xBB; SFR Page = 0x00; Bit Name Function 7:6 Unused Read = 00b; Write = Don’t Care. 5:0 AMX0P[5:0] AMUX0 Positive Input Selection. 000000: P0.0 000001: P0.1 000010: P0.2 000011: P0.3 000100: P0.4 000101: P0.5 000110: P0.6 000111: P0.7 001000: P1.0 001001: P1.1 001010: P1.2 001011: P1.3 001100: P1.4 001101: P1.5 001110: P1.6 001111: P1.7 010000: P2.0 010001: P2.1 010010: P2.2 010011: P2.3 010100: P2.4 010101: P2.5 010110: P2.6 010111: P2.7 011000: P3.0 011001: P3.1 (Only available on 48-pin and 40-pin package devices) 011010: P3.2 (Only available on 48-pin and 40-pin package devices) 011011: P3.3 (Only available on 48-pin and 40-pin package devices) 011100: P3.4 (Only available on 48-pin and 40-pin package devices) 011101: P3.5 (Only available on 48-pin and 40-pin package devices) 011110: P3.6 (Only available on 48-pin and 40-pin package devices) 011111: P3.7 (Only available on 48-pin and 40-pin package devices) 100000–101111: Reserved 110000: Temp Sensor 110001: V DD 110010–111111: GND 71 Rev. 1.2

C8051F50x/F51x 7. Temperature Sensor An on-chip temperature sensor is included on the C8051F50x/F51x devices which can be directly accessed via the ADC multiplexer in single-ended configuration. To use the ADC to measure the tempera- ture sensor, the ADC multiplexer channel should be configured to connect to the temperature sensor. The temperature sensor transfer function is shown in Figure 7.1. The output voltage (V ) is the positive TEMP ADC input is selected by bits AD0MX[4:0] in register ADC0MX. The TEMPE bit in register REF0CN enables/disables the temperature sensor, as described in SFR Definition 8.1. While disabled, the tempera- ture sensor defaults to a high impedance state and any ADC measurements performed on the sensor will result in meaningless data. Refer to Table 5.10 for the slope and offset parameters of the temperature sen- sor. V = (Slope x Temp ) + Offset TEMP C Temp = (V - Offset) / Slope C TEMP Slope (V / deg C) e g a t l o Offset (V at 0 Celsius) V Temperature Figure 7.1. Temperature Sensor Transfer Function Rev. 1.2 72

C8051F50x/F51x 8. Voltage Reference The Voltage reference multiplexer on the C8051F50x/F51x devices is configurable to use an externally connected voltage reference, the on-chip reference voltage generator routed to the VREF pin, or the V DD power supply voltage (see Figure 8.1). The REFSL bit in the Reference Control register (REF0CN, SFR Definition 8.1) selects the reference source for the ADC. For an external source or the on-chip reference, REFSL should be set to 0 to select the VREF pin. To use V as the reference source, REFSL should be DD set to 1. The BIASE bit enables the internal voltage bias generator, which is used by the ADC, Temperature Sensor, and internal oscillator. This bias is automatically enabled when any peripheral which requires it is enabled, and it does not need to be enabled manually. The bias generator may be enabled manually by writing a 1 to the BIASE bit in register REF0CN. The electrical specifications for the voltage reference circuit are given in Table 5.11. The on-chip voltage reference circuit consists of a temperature stable bandgap voltage reference genera- tor and a gain-of-two output buffer amplifier. The output voltage is selectable between 1.5 V and 2.25 V. The on-chip voltage reference can be driven on the VREF pin by setting the REFBE bit in register REF0CN to a 1. The maximum load seen by the VREF pin must be less than 200 µA to GND. Bypass capacitors of 0.1 µF and 4.7 µF are recommended from the VREF pin to GND. If the on-chip reference is not used, the REFBE bit should be cleared to 0. Electrical specifications for the on-chip voltage reference are given in Table 5.11. Important Note about the VREF Pin: When using either an external voltage reference or the on-chip ref- erence circuitry, the VREF pin should be configured as an analog pin and skipped by the Digital Crossbar. Refer to Section “20. Port Input/Output” on page 177 for the location of the VREF pin, as well as details of how to configure the pin in analog mode and to be skipped by the crossbar. REF0CN REFSLTEMPEBIASEREFBE EN To ADC, Internal Bias Generator Oscillators IOSCE N VDD External Voltage EN Reference Temp Sensor To Analog Mux R1 Circuit VREF 0 VREF (to ADC) GND VDD 1 REFBE 4.7μF + 0.1μF EN Internal Recommended Bypass Reference Capacitors Figure 8.1. Voltage Reference Functional Block Diagram Rev. 1.2 73

C8051F50x/F51x SFR Definition 8.1. REF0CN: Reference Control Bit 7 6 5 4 3 2 1 0 Name ZTCEN REFLV REFSL TEMPE BIASE REFBE Type R R R R R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD1; SFR Page = 0x00 Bit Name Function 7:6 Unused Read = 00b; Write = don’t care. 5 ZTCEN Zero Temperature Coefficient Bias Enable Bit. This bit must be set to 1b before entering oscillator suspend mode. 0: ZeroTC Bias Generator automatically enabled when required. 1: ZeroTC Bias Generator forced on. 4 REFLV Voltage Reference Output Level Select. This bit selects the output voltage level for the internal voltage reference 0: Internal voltage reference set to 1.5 V. 1: Internal voltage reference set to 2.20 V. 3 REFSL Voltage Reference Select. This bit selects the ADCs voltage reference. 0: V pin used as voltage reference. REF 1: V used as voltage reference. DD 2 TEMPE Temperature Sensor Enable Bit. 0: Internal Temperature Sensor off. 1: Internal Temperature Sensor on. 1 BIASE Internal Analog Bias Generator Enable Bit. 0: Internal Bias Generator off. 1: Internal Bias Generator on. 0 REFBE On-chip Reference Buffer Enable Bit. 0: On-chip Reference Buffer off. 1: On-chip Reference Buffer on. Internal voltage reference driven on the V pin. REF 74 Rev. 1.2

C8051F50x/F51x 9. Comparators The C8051F50x/F51x devices include two on-chip programmable voltage Comparators. A block diagram of the comparators is shown in Figure 9.1, where “n” is the comparator number (0 or 1). The two Compara- tors operate identically except that Comparator0 can also be used a reset source. For input selection details, refer to SFR Definition 9.5 and SFR Definition 9.6. Each Comparator offers programmable response time and hysteresis, an analog input multiplexer, and two outputs that are optionally available at the Port pins: a synchronous “latched” output (CP0, CP1), or an asynchronous “raw” output (CP0A, CP1A). The asynchronous signal is available even when the system clock is not active. This allows the Comparators to operate and generate an output with the device in STOP mode. When assigned to a Port pin, the Comparator outputs may be configured as open drain or push-pull (see Section “20.4. Port I/O Initialization” on page 182). Comparator0 may also be used as a reset source (see Section “17.5. Comparator0 Reset” on page 145). The Comparator0 inputs are selected in the CPT0MX register (SFR Definition 9.5). The CMX0P1-CMX0P0 bits select the Comparator0 positive input; the CMX0N1-CMX0N0 bits select the Comparator0 negative input. The Comparator1 inputs are selected in the CPT1MX register (SFR Definition 9.6). The CMX1P1- CMX1P0 bits select the Comparator1 positive input; the CMX1N1-CMX1N0 bits select the Comparator1 negative input. Important Note About Comparator Inputs: The Port pins selected as Comparator inputs should be con- figured as analog inputs in their associated Port configuration register, and configured to be skipped by the Crossbar (for details on Port configuration, see Section “20.1. Port I/O Modes of Operation” on page 178). CPTnCN CPnHYN0 CPnHYN1 CPnHYP0 CPnHYP1 CPnFIF CPnRIF CPnOUT CPnEN VIO CPn + + Comparator CPn Input Mux CPn - DSETQ DSETQ - CLRQ CLRQ Crossbar (SYNCHRONIZER) CPnA GND CPTnMD Reset Decision Tree C C C C PnM PnM PnF PnR D0 D1 IE IE CPnRIF 0 CPnEN EA CPn 1 0 0 Interrupt 0 1 1 CPnFIF 1 Figure 9.1. Comparator Functional Block Diagram Rev. 1.2 75

C8051F50x/F51x Comparator outputs can be polled in software, used as an interrupt source, and/or routed to a Port pin. When routed to a Port pin, Comparator outputs are available asynchronous or synchronous to the system clock; the asynchronous output is available even in STOP mode (with no system clock active). When dis- abled, the Comparator output (if assigned to a Port I/O pin via the Crossbar) defaults to the logic low state, and the power supply to the comparator is turned off. See Section “20.3. Priority Crossbar Decoder” on page 180 for details on configuring Comparator outputs via the digital Crossbar. Comparator inputs can be externally driven from –0.25 V to (V ) + 0.25 V without damage or upset. The complete Comparator elec- DD trical specifications are given in Table 5.12. The Comparator response time may be configured in software via the CPTnMD registers (see SFR Defini- tion 9.2). Selecting a longer response time reduces the Comparator supply current. See Table 5.12 on page 51 for complete timing and supply current requirements. CPn+ VIN+ + CPn OUT VIN- CPn- _ CIRCUIT CONFIGURATION Positive Hysteresis Voltage (Programmed with CPnHYP Bits) VIN- INPUTS Negative Hysteresis Voltage (Programmed by CPnHYN Bits) VIN+ VOH OUTPUT VOL Negative Hysteresis Maximum Disabled Negative Hysteresis Positive Hysteresis Maximum Disabled Positive Hysteresis Figure 9.2. Comparator Hysteresis Plot Comparator hysteresis is software-programmable via its Comparator Control register CPTnCN. The amount of negative hysteresis voltage is determined by the settings of the CPnHYN bits. As shown in Figure 9.2, various levels of negative hysteresis can be programmed, or negative hysteresis can be dis- abled. In a similar way, the amount of positive hysteresis is determined by the setting the CPnHYP bits. Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Inter- rupt enable and priority control, see “14. Interrupts” on page 117.) The CPnFIF flag is set to 1 upon a Com- parator falling-edge, and the CPnRIF flag is set to 1 upon the Comparator rising-edge. Once set, these bits remain set until cleared by software. The output state of the Comparator can be obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to 1, and is disabled by clearing this bit to 0. 76 Rev. 1.2

C8051F50x/F51x Note that false rising edges and falling edges can be detected when the comparator is first powered on or if changes are made to the hysteresis or response time control bits. Therefore, it is recommended that the rising-edge and falling-edge flags be explicitly cleared to logic 0 a short time after the comparator is enabled or its mode bits have been changed. SFR Definition 9.1. CPT0CN: Comparator0 Control Bit 7 6 5 4 3 2 1 0 Name CP0EN CP0OUT CP0RIF CP0FIF CP0HYP[1:0] CP0HYN[1:0] Type R/W R R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x9A; SFR Page = 0x00 Bit Name Function 7 CP0EN Comparator0 Enable Bit. 0: Comparator0 Disabled. 1: Comparator0 Enabled. 6 CP0OUT Comparator0 Output State Flag. 0: Voltage on CP0+ < CP0–. 1: Voltage on CP0+ > CP0–. 5 CP0RIF Comparator0 Rising-Edge Flag. Must be cleared by software. 0: No Comparator0 Rising Edge has occurred since this flag was last cleared. 1: Comparator0 Rising Edge has occurred. 4 CP0FIF Comparator0 Falling-Edge Flag. Must be cleared by software. 0: No Comparator0 Falling-Edge has occurred since this flag was last cleared. 1: Comparator0 Falling-Edge has occurred. 3:2 CP0HYP[1:0] Comparator0 Positive Hysteresis Control Bits. 00: Positive Hysteresis Disabled. 01: Positive Hysteresis = 5 mV. 10: Positive Hysteresis = 10 mV. 11: Positive Hysteresis = 20 mV. 1:0 CP0HYN[1:0] Comparator0 Negative Hysteresis Control Bits. 00: Negative Hysteresis Disabled. 01: Negative Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 20 mV. Rev. 1.2 77

C8051F50x/F51x SFR Definition 9.2. CPT0MD: Comparator0 Mode Selection Bit 7 6 5 4 3 2 1 0 Name CP0RIE CP0FIE CP0MD[1:0] Type R R R/W R/W R R R/W Reset 0 0 0 0 0 0 1 0 SFR Address = 0x9B; SFR Page = 0x00 Bit Name Function 7:6 Unused Read = 00b, Write = Don’t Care. 5 CP0RIE Comparator0 Rising-Edge Interrupt Enable. 0: Comparator0 Rising-edge interrupt disabled. 1: Comparator0 Rising-edge interrupt enabled. 4 CP0FIE Comparator0 Falling-Edge Interrupt Enable. 0: Comparator0 Falling-edge interrupt disabled. 1: Comparator0 Falling-edge interrupt enabled. 3:2 Unused Read = 00b, Write = don’t care. 1:0 CP0MD[1:0] Comparator0 Mode Select. These bits affect the response time and power consumption for Comparator0. 00: Mode 0 (Fastest Response Time, Highest Power Consumption) 01: Mode 1 10: Mode 2 11: Mode 3 (Slowest Response Time, Lowest Power Consumption) 78 Rev. 1.2

C8051F50x/F51x SFR Definition 9.3. CPT1CN: Comparator1 Control Bit 7 6 5 4 3 2 1 0 Name CP1EN CP1OUT CP1RIF CP1FIF CP1HYP[1:0] CP1HYN[1:0] Type R/W R R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x9D; SFR Page = 0x00 Bit Name Function 7 CP1EN Comparator1 Enable Bit. 0: Comparator1 Disabled. 1: Comparator1 Enabled. 6 CP1OUT Comparator1 Output State Flag. 0: Voltage on CP1+ < CP1–. 1: Voltage on CP1+ > CP1–. 5 CP1RIF Comparator1 Rising-Edge Flag. Must be cleared by software. 0: No Comparator1 Rising Edge has occurred since this flag was last cleared. 1: Comparator1 Rising Edge has occurred. 4 CP1FIF Comparator1 Falling-Edge Flag. Must be cleared by software. 0: No Comparator1 Falling-Edge has occurred since this flag was last cleared. 1: Comparator1 Falling-Edge has occurred. 3:2 CP1HYP[1:0] Comparator1 Positive Hysteresis Control Bits. 00: Positive Hysteresis Disabled. 01: Positive Hysteresis = 5 mV. 10: Positive Hysteresis = 10 mV. 11: Positive Hysteresis = 20 mV. 1:0 CP1HYN[1:0] Comparator1 Negative Hysteresis Control Bits. 00: Negative Hysteresis Disabled. 01: Negative Hysteresis = 5 mV. 10: Negative Hysteresis = 10 mV. 11: Negative Hysteresis = 20 mV. Rev. 1.2 79

C8051F50x/F51x SFR Definition 9.4. CPT1MD: Comparator1 Mode Selection Bit 7 6 5 4 3 2 1 0 Name CP1RIE CP1FIE CP1MD[1:0] Type R R R/W R/W R R R/W Reset 0 0 0 0 0 0 1 0 SFR Address = 0x9E; SFR Page = 0x00 Bit Name Function 7:6 Unused Read = 00b, Write = Don’t Care. 5 CP1RIE Comparator1 Rising-Edge Interrupt Enable. 0: Comparator1 Rising-edge interrupt disabled. 1: Comparator1 Rising-edge interrupt enabled. 4 CP1FIE Comparator1 Falling-Edge Interrupt Enable. 0: Comparator1 Falling-edge interrupt disabled. 1: Comparator1 Falling-edge interrupt enabled. 3:2 Unused Read = 00b, Write = don’t care. 1:0 CP1MD[1:0] Comparator1 Mode Select. These bits affect the response time and power consumption for Comparator1. 00: Mode 0 (Fastest Response Time, Highest Power Consumption) 01: Mode 1 10: Mode 2 11: Mode 3 (Slowest Response Time, Lowest Power Consumption) 80 Rev. 1.2

C8051F50x/F51x 9.1. Comparator Multiplexer C8051F50x/F51x devices include an analog input multiplexer for each of the comparators to connect Port I/O pins to the comparator inputs. The Comparator0 inputs are selected in the CPT0MX register (SFR Defi- nition 9.5). The CMX0P3–CMX0P0 bits select the Comparator0 positive input; the CMX0N3–CMX0N0 bits select the Comparator0 negative input. Similarly, the Comparator1 inputs are selected in the CPT1MX reg- ister using the CMX1P3-CMX1P0 bits and CMX1N3-CMX1N0 bits. The same pins are available to both multiplexers at the same time and can be used by both comparators simultaneously. Important Note About Comparator Inputs: The Port pins selected as comparator inputs should be con- figured as analog inputs in their associated Port configuration register, and configured to be skipped by the Crossbar (for details on Port configuration, see Section “20.6. Special Function Registers for Accessing and Configuring Port I/O” on page 191). CMXnN3 CMXnN2 CMXnN1 X M CMXnN0 n T CMXnP3 P C CMXnP2 CMXnP1 CMXnP0 P0.0 VDD P0.2 P0.1 P0.4 CPn + P0.3 P0.6 P0.5 + P1.0 P0.7 P1.2 - P1.1 P1.4 P1.3 GND P1.6 P1.5 P2.0 P1.7 P2.2 P2.1 P2.4 P2.3 P2.6 P2.5 P2.7 CPn - Figure 9.3. Comparator Input Multiplexer Block Diagram Rev. 1.2 81

C8051F50x/F51x SFR Definition 9.5. CPT0MX: Comparator0 MUX Selection Bit 7 6 5 4 3 2 1 0 Name CMX0N[3:0] CMX0P[3:0] Type R/W R/W Reset 0 1 1 1 0 1 1 1 SFR Address = 0x9C; SFR Page = 0x00 Bit Name Function 7:4 CMX0N[3:0] Comparator0 Negative Input MUX Selection. 0000: P0.1 0001: P0.3 0010: P0.5 0011: P0.7 0100: P1.1 0101: P1.3 0110: P1.5 0111: P1.7 1000: P2.1 1001: P2.3 1010: P2.5 1011: P2.7 1100–1111: None 3:0 CMX0P[3:0] Comparator0 Positive Input MUX Selection. 0000: P0.0 0001: P0.2 0010: P0.4 0011: P0.6 0100: P1.0 0101: P1.2 0110: P1.4 0111: P1.6 1000: P2.0 1001: P2.2 1010: P2.4 1011: P2.6 1100–1111: None 82 Rev. 1.2

C8051F50x/F51x SFR Definition 9.6. CPT1MX: Comparator1 MUX Selection Bit 7 6 5 4 3 2 1 0 Name CMX1N[3:0] CMX1P[3:0] Type R/W R/W Reset 0 1 1 1 0 1 1 1 SFR Address = 0x9F; SFR Page = 0x00 Bit Name Function 7:4 CMX1N[3:0] Comparator1 Negative Input MUX Selection. 0000: P0.1 0001: P0.3 0010: P0.5 0011: P0.7 0100: P1.1 0101: P1.3 0110: P1.5 0111: P1.7 1000: P2.1 1001: P2.3 1010: P2.5 1011: P2.7 1100–1111: None 3:0 CMX1P[3:0] Comparator1 Positive Input MUX Selection. 0000: P0.0 0001: P0.2 0010: P0.4 0011: P0.6 0100: P1.0 0101: P1.2 0110: P1.4 0111: P1.6 1000: P2.0 1001: P2.2 1010: P2.4 1011: P2.6 1100–1111: None Rev. 1.2 83

C8051F50x/F51x 10. Voltage Regulator (REG0) C8051F50x/F51x devices include an on-chip low dropout voltage regulator (REG0). The input to REG0 at the V pin can be as high as 5.25 V. The output can be selected by software to 2.1 V or 2.6 V. When REGIN enabled, the output of REG0 appears on the V pin, powers the microcontroller core, and can be used to DD power external devices. On reset, REG0 is enabled and can be disabled by software. The Voltage regulator can generate an interrupt (if enabled by EREG0, EIE2.0) that is triggered whenever the V input voltage drops below the dropout threshold voltage. This dropout interrupt has no pending REGIN flag and the recommended procedure to use it is as follows: 1. Wait enough time to ensure the V input voltage is stable REGIN 2. Enable the dropout interrupt (EREG0, EIE2.0) and select the proper priority (PREG0, EIP2.0) 3. If triggered, inside the interrupt disable it (clear EREG0, EIE2.0), execute all procedures necessary to protect your application (put it in a safe mode and leave the interrupt now disabled. 4. In the main application, now running in the safe mode, regularly checks the DROPOUT bit (REG0CN.0). Once it is cleared by the regulator hardware the application can enable the interrupt again (EREG0, EIE1.6) and return to the normal mode operation. The input (V ) and output (V ) of the voltage regulator should both be bypassed with a large capaci- REGIN DD tor (4.7 µF + 0.1 µF) to ground as shown in Figure 10.1 below. This capacitor will eliminate power spikes and provide any immediate power required by the microcontroller. The settling time associated with the voltage regulator is shown in Table X. REG0 V REGIN 4.7 µF .1 µF V V DD DD 4.7 µF .1 µF Figure 10.1. External Capacitors for Voltage Regulator Input/Output— Regulator Enabled If the internal voltage regulator is not used, the VREGIN input should be tied to VDD, as shown in Figure 10.2. Rev. 1.2 84

C8051F50x/F51x V REGIN V V DD DD 4.7 µF .1 µF Figure 10.2. External Capacitors for Voltage Regulator Input/Output— Regulator Disabled SFR Definition 10.1. REG0CN: Regulator Control Bit 7 6 5 4 3 2 1 0 Name REGDIS Reserved REG0MD DROPOUT Type R/W R/W R R/W R R R R Reset 0 1 0 1 0 0 0 0 SFR Address = 0xC9; SFR Page = 0x00 Bit Name Function 7 REGDIS Voltage Regulator Disable Bit. 0: Voltage Regulator Enabled 1: Voltage Regulator Disabled 6 Reserved Read = 1b; Must Write 1b. 5 Unused Read = 0b; Write = Don’t Care. 4 REG0MD Voltage Regulator Mode Select Bit. 0: Voltage Regulator Output is 2.1V. 1: Voltage Regulator Output is 2.6V. 3:1 Unused Read = 000b. Write = Don’t Care. 0 DROPOUT Voltage Regulator Dropout Indicator. 0: Voltage Regulator is not in dropout 1: Voltage Regulator is in or near dropout. 85 Rev. 1.2

C8051F50x/F51x 11. CIP-51 Microcontroller The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop soft- ware. The MCU family has a superset of all the peripherals included with a standard 8051. The CIP-51 also includes on-chip debug hardware (see description in Section 28), and interfaces directly with the ana- log and digital subsystems providing a complete data acquisition or control-system solution in a single inte- grated circuit. The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as additional custom peripherals and functions to extend its capability (see Figure 11.1 for a block diagram). The CIP-51 includes the following features:  Fully Compatible with MCS-51 Instruction Set  50 MIPS Peak Throughput with 50 MHz Clock  0 to 50 MHz Clock Frequency  Extended Interrupt Handler  Reset Input  Power Management Modes  On-chip Debug Logic  Program and Data Memory Security 11.1. Performance The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the stan- dard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51 core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more than eight system clock cycles. Rev. 1.2 86

C8051F50x/F51x DATA BUS D8 D8 D8 ACCUMULATOR D8 D8 B REGISTER STACK POINTER S U B TMP1 TMP2 A T A SRAM D PSW ADDRESS SRAM ALU REGISTER D8 D8 D8 D8 DATA BUS SFR_ADDRESS BUFFER D8 SFR_CONTROL SFR DATA POINTER D8 D8 INTEBRUFSACE SFR_WRITE_DATA SFR_READ_DATA PC INCREMENTER PROGRAM COUNTER (PC) US D8 MEM_ADDRESS B PRGM. ADDRESS REG. ATA A16 INMTEEMROFARCYE MEMM_EWMR_CITOEN_DTRAOTAL D MEM_READ_DATA PIPELINE D8 RESET CONTROL LOGIC SYSTEM_IRQs CLOCK INTERRUPT STOP D8 INTERFACE EMULATION_IRQ POWER CONTROL IDLE REGISTER D8 Figure 11.1. CIP-51 Block Diagram With the CIP-51's maximum system clock at 50 MHz, it has a peak throughput of 50 MIPS. The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that require each execu- tion time. Clocks to Execute 1 2 2/3 3 3/4 4 4/5 5 8 Number of Instructions 26 50 5 14 7 3 1 2 1 Programming and Debugging Support In-system programming of the Flash program memory and communication with on-chip debug support logic is accomplished via the Silicon Labs 2-Wire Development Interface (C2). The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware breakpoints, starting, stopping and single stepping through program execution (including interrupt service routines), examination of the program's call stack, and reading/writing the contents of registers and mem- ory. This method of on-chip debugging is completely non-intrusive, requiring no RAM, Stack, timers, or other on-chip resources. C2 details can be found in Section “28. C2 Interface” on page 306. The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs pro- vides an integrated development environment (IDE) including editor, debugger and programmer. The IDE's debugger and programmer interface to the CIP-51 via the C2 interface to provide fast and efficient in-sys- tem device programming and debugging. Third party macro assemblers and C compilers are also avail- able. 87 Rev. 1.2

C8051F50x/F51x 11.2. Instruction Set The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruc- tion set. Standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51 instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes, addressing modes and effect on PSW flags. However, instruction timing is different than that of the stan- dard 8051. 11.2.1. Instruction and CPU Timing In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based solely on clock cycle timing. All instruction timings are specified in terms of clock cycles. Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 11.1 is the CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock cycles for each instruction. Rev. 1.2 88

C8051F50x/F51x Table 11.1. CIP-51 Instruction Set Summary (Prefetch-Enabled) Mnemonic Description Bytes Clock Cycles Arithmetic Operations ADD A, Rn Add register to A 1 1 ADD A, direct Add direct byte to A 2 2 ADD A, @Ri Add indirect RAM to A 1 2 ADD A, #data Add immediate to A 2 2 ADDC A, Rn Add register to A with carry 1 1 ADDC A, direct Add direct byte to A with carry 2 2 ADDC A, @Ri Add indirect RAM to A with carry 1 2 ADDC A, #data Add immediate to A with carry 2 2 SUBB A, Rn Subtract register from A with borrow 1 1 SUBB A, direct Subtract direct byte from A with borrow 2 2 SUBB A, @Ri Subtract indirect RAM from A with borrow 1 2 SUBB A, #data Subtract immediate from A with borrow 2 2 INC A Increment A 1 1 INC Rn Increment register 1 1 INC direct Increment direct byte 2 2 INC @Ri Increment indirect RAM 1 2 DEC A Decrement A 1 1 DEC Rn Decrement register 1 1 DEC direct Decrement direct byte 2 2 DEC @Ri Decrement indirect RAM 1 2 INC DPTR Increment Data Pointer 1 1 MUL AB Multiply A and B 1 4 DIV AB Divide A by B 1 8 DA A Decimal adjust A 1 1 Logical Operations ANL A, Rn AND Register to A 1 1 ANL A, direct AND direct byte to A 2 2 ANL A, @Ri AND indirect RAM to A 1 2 ANL A, #data AND immediate to A 2 2 ANL direct, A AND A to direct byte 2 2 ANL direct, #data AND immediate to direct byte 3 3 ORL A, Rn OR Register to A 1 1 ORL A, direct OR direct byte to A 2 2 ORL A, @Ri OR indirect RAM to A 1 2 ORL A, #data OR immediate to A 2 2 ORL direct, A OR A to direct byte 2 2 ORL direct, #data OR immediate to direct byte 3 3 XRL A, Rn Exclusive-OR Register to A 1 1 XRL A, direct Exclusive-OR direct byte to A 2 2 XRL A, @Ri Exclusive-OR indirect RAM to A 1 2 Note: Certain instructions take a variable number of clock cycles to execute depending on instruction alignment and the FLRT setting (SFR Definition 15.3). 89 Rev. 1.2

C8051F50x/F51x Table 11.1. CIP-51 Instruction Set Summary (Prefetch-Enabled)(Continued) Mnemonic Description Bytes Clock Cycles XRL A, #data Exclusive-OR immediate to A 2 2 XRL direct, A Exclusive-OR A to direct byte 2 2 XRL direct, #data Exclusive-OR immediate to direct byte 3 3 CLR A Clear A 1 1 CPL A Complement A 1 2 RL A Rotate A left 1 1 RLC A Rotate A left through Carry 1 1 RR A Rotate A right 1 1 RRC A Rotate A right through Carry 1 1 SWAP A Swap nibbles of A 1 1 Data Transfer MOV A, Rn Move Register to A 1 1 MOV A, direct Move direct byte to A 2 2 MOV A, @Ri Move indirect RAM to A 1 2 MOV A, #data Move immediate to A 2 2 MOV Rn, A Move A to Register 1 1 MOV Rn, direct Move direct byte to Register 2 2 MOV Rn, #data Move immediate to Register 2 2 MOV direct, A Move A to direct byte 2 2 MOV direct, Rn Move Register to direct byte 2 2 MOV direct, direct Move direct byte to direct byte 3 3 MOV direct, @Ri Move indirect RAM to direct byte 2 2 MOV direct, #data Move immediate to direct byte 3 3 MOV @Ri, A Move A to indirect RAM 1 2 MOV @Ri, direct Move direct byte to indirect RAM 2 2 MOV @Ri, #data Move immediate to indirect RAM 2 2 MOV DPTR, #data16 Load DPTR with 16-bit constant 3 3 MOVC A, @A+DPTR Move code byte relative DPTR to A 1 4-7* MOVC A, @A+PC Move code byte relative PC to A 1 3 MOVX A, @Ri Move external data (8-bit address) to A 1 3 MOVX @Ri, A Move A to external data (8-bit address) 1 3 MOVX A, @DPTR Move external data (16-bit address) to A 1 3 MOVX @DPTR, A Move A to external data (16-bit address) 1 3 PUSH direct Push direct byte onto stack 2 2 POP direct Pop direct byte from stack 2 2 XCH A, Rn Exchange Register with A 1 1 XCH A, direct Exchange direct byte with A 2 2 XCH A, @Ri Exchange indirect RAM with A 1 2 XCHD A, @Ri Exchange low nibble of indirect RAM with A 1 2 Boolean Manipulation CLR C Clear Carry 1 1 CLR bit Clear direct bit 2 2 Note: Certain instructions take a variable number of clock cycles to execute depending on instruction alignment and the FLRT setting (SFR Definition 15.3). Rev. 1.2 90

C8051F50x/F51x Table 11.1. CIP-51 Instruction Set Summary (Prefetch-Enabled)(Continued) Mnemonic Description Bytes Clock Cycles SETB C Set Carry 1 1 SETB bit Set direct bit 2 2 CPL C Complement Carry 1 1 CPL bit Complement direct bit 2 2 ANL C, bit AND direct bit to Carry 2 2 ANL C, /bit AND complement of direct bit to Carry 2 2 ORL C, bit OR direct bit to carry 2 2 ORL C, /bit OR complement of direct bit to Carry 2 2 MOV C, bit Move direct bit to Carry 2 2 MOV bit, C Move Carry to direct bit 2 2 JC rel Jump if Carry is set 2 2/(4-6)* JNC rel Jump if Carry is not set 2 2/(4-6)* JB bit, rel Jump if direct bit is set 3 3/(5-7)* JNB bit, rel Jump if direct bit is not set 3 3/(5-7)* JBC bit, rel Jump if direct bit is set and clear bit 3 3/(5-7)* Program Branching ACALL addr11 Absolute subroutine call 2 4-6* LCALL addr16 Long subroutine call 3 5-7* RET Return from subroutine 1 6-8* RETI Return from interrupt 1 6-8* AJMP addr11 Absolute jump 2 4-6* LJMP addr16 Long jump 3 5-7* SJMP rel Short jump (relative address) 2 4-6* JMP @A+DPTR Jump indirect relative to DPTR 1 3-5* JZ rel Jump if A equals zero 2 2/(4-6)* JNZ rel Jump if A does not equal zero 2 2/(4-6)* CJNE A, direct, rel Compare direct byte to A and jump if not equal 3 4/(6-8)* CJNE A, #data, rel Compare immediate to A and jump if not equal 3 3/(6-8)* CJNE Rn, #data, rel Compare immediate to Register and jump if not 3 3/(5-7)* equal CJNE @Ri, #data, rel Compare immediate to indirect and jump if not 3 4/(6-8)* equal DJNZ Rn, rel Decrement Register and jump if not zero 2 2/(4-6)* DJNZ direct, rel Decrement direct byte and jump if not zero 3 3/(5-7)* NOP No operation 1 1 Note: Certain instructions take a variable number of clock cycles to execute depending on instruction alignment and the FLRT setting (SFR Definition 15.3). 91 Rev. 1.2

C8051F50x/F51x Notes on Registers, Operands and Addressing Modes: Rn—Register R0–R7 of the currently selected register bank. @Ri—Data RAM location addressed indirectly through R0 or R1. rel—8-bit, signed (two’s complement) offset relative to the first byte of the following instruction. Used by SJMP and all conditional jumps. direct—8-bit internal data location’s address. This could be a direct-access Data RAM location (0x00– 0x7F) or an SFR (0x80–0xFF). #data—8-bit constant #data16—16-bit constant bit—Direct-accessed bit in Data RAM or SFR addr11—11-bit destination address used by ACALL and AJMP. The destination must be within the same 2 kB page of program memory as the first byte of the following instruction. addr16—16-bit destination address used by LCALL and LJMP. The destination may be anywhere within the 64 kB program memory space. There is one unused opcode (0xA5) that performs the same function as NOP. All mnemonics copyrighted © Intel Corporation 1980. 11.3. CIP-51 Register Descriptions Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits should not be set to logic l. Future product versions may use these bits to implement new features in which case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of the remaining SFRs are included in the sections of the datasheet associated with their corresponding sys- tem function. Rev. 1.2 92

C8051F50x/F51x SFR Definition 11.1. DPL: Data Pointer Low Byte Bit 7 6 5 4 3 2 1 0 Name DPL[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x82; SFR Page = All Pages Bit Name Function 7:0 DPL[7:0] Data Pointer Low. The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indi- rectly addressed Flash memory or XRAM. SFR Definition 11.2. DPH: Data Pointer High Byte Bit 7 6 5 4 3 2 1 0 Name DPH[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x83; SFR Page = All Pages Bit Name Function 7:0 DPH[7:0] Data Pointer High. The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indi- rectly addressed Flash memory or XRAM. 93 Rev. 1.2

C8051F50x/F51x SFR Definition 11.3. SP: Stack Pointer Bit 7 6 5 4 3 2 1 0 Name SP[7:0] Type R/W Reset 0 0 0 0 0 1 1 1 SFR Address = 0x81; SFR Page = All Pages Bit Name Function 7:0 SP[7:0] Stack Pointer. The Stack Pointer holds the location of the top of the stack. The stack pointer is incre- mented before every PUSH operation. The SP register defaults to 0x07 after reset. SFR Definition 11.4. ACC: Accumulator Bit 7 6 5 4 3 2 1 0 Name ACC[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xE0; SFR Page = All Pages; Bit-Addressable Bit Name Function 7:0 ACC[7:0] Accumulator. This register is the accumulator for arithmetic operations. SFR Definition 11.5. B: B Register Bit 7 6 5 4 3 2 1 0 Name B[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xF0; SFR Page = All Pages; Bit-Addressable Bit Name Function 7:0 B[7:0] B Register. This register serves as a second accumulator for certain arithmetic operations. Rev. 1.2 94

C8051F50x/F51x SFR Definition 11.6. PSW: Program Status Word Bit 7 6 5 4 3 2 1 0 Name CY AC F0 RS[1:0] OV F1 PARITY Type R/W R/W R/W R/W R/W R/W R Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD0; SFR Page = All Pages; Bit-Addressable Bit Name Function 7 CY Carry Flag. This bit is set when the last arithmetic operation resulted in a carry (addition) or a bor- row (subtraction). It is cleared to logic 0 by all other arithmetic operations. 6 AC Auxiliary Carry Flag. This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow from (subtraction) the high order nibble. It is cleared to logic 0 by all other arith- metic operations. 5 F0 User Flag 0. This is a bit-addressable, general purpose flag for use under software control. 4:3 RS[1:0] Register Bank Select. These bits select which register bank is used during register accesses. 00: Bank 0, Addresses 0x00-0x07 01: Bank 1, Addresses 0x08-0x0F 10: Bank 2, Addresses 0x10-0x17 11: Bank 3, Addresses 0x18-0x1F 2 OV Overflow Flag. This bit is set to 1 under the following circumstances:  An ADD, ADDC, or SUBB instruction causes a sign-change overflow.  A MUL instruction results in an overflow (result is greater than 255).  A DIV instruction causes a divide-by-zero condition. The OV bit is cleared to 0 by the ADD, ADDC, SUBB, MUL, and DIV instructions in all other cases. 1 F1 User Flag 1. This is a bit-addressable, general purpose flag for use under software control. 0 PARITY Parity Flag. This bit is set to logic 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum is even. 95 Rev. 1.2

C8051F50x/F51x 11.4. Serial Number Special Function Registers (SFRs) The C8051F50x/F51x devices include four SFRs, SN0 through SN3, that are pre-programmed during pro- duction with a unique, 32-bit serial number. The serial number provides a unique identification number for each device and can be read from the application firmware. If the serial number is not used in the applica- tion, these four registers can be used as general purpose SFRs. SFR Definition 11.7. SNn: Serial Number n Bit 7 6 5 4 3 2 1 0 Name SERNUMn[7:0] Type R/W Reset Varies—Unique 32-bit value SFR Addresses: SN0 = 0xF9; SN1 = 0xFA; SN2 = 0xFB; SN3 = 0xFC; SFR Page = 0x0F; Bit Name Function 7:0 SERNUMn[7:0] Serial Number Bits. The four serial number registers form a 32-bit serial number, with SN3 as the most significant byte and SN0 as the least significant byte. Rev. 1.2 96

C8051F50x/F51x 12. Memory Organization The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are two separate memory spaces: program memory and data memory. Program and data memory share the same address space but are accessed via different instruction types. The memory organization is shown in Figure 12.1 PROGRAM/DATA MEMORY DATA MEMORY (RAM) (FLASH) INTERNAL DATA ADDRESS SPACE C8051F500/1/2/3/8/9 0xFF Upper 128 RAM Special Function (Indirect Addressing Register's RESERVED 0xFC00 0x80 Only) (Direct Addressing Only) 0xFBFF 0x7F (Direct and Indirect Addressing) Lower 128 RAM 64 kB FLASH 0x30 (Direct and Indirect 0x2F Addressing) (In-System Bit Addressable Programmable in 512 0x20 Byte Sectors) 0x1F General Purpose 0x00 Registers 0x0000 EXTERNAL DATA ADDRESS SPACE 0xFFFF Same 4096 bytes as from 0x0000 to 0x0FFF, C8051F504/5/6/7-F510/1 wrapped on 4096-byte 0x7FFF boundaries 0x1000 32 kB FLASH 0x0FFF XRAM (In-System Programmable in 512 4K Bytes Byte Sectors) (accessable using MOVX instruction) 0x0000 0x0000 Figure 12.1. C8051F50x/F51x Memory Map Rev. 1.2 97

C8051F50x/F51x 12.1. Program Memory The CIP-51 core has a 64 kB program memory space. The C8051F50x/F51x devices implement 64 kB or 32 kB of this program memory space as in-system, re-programmable Flash memory, organized in a contig- uous block from addresses 0x0000 to 0xFFFF in 64 kB devices and addresses 0x0000 to 0x7FFF in 32 kB devices. The address 0xFBFF in 64 kB devices and 0x7FFF in 32 kB devices serves as the security lock byte for the device. Addresses above 0xFDFF are reserved in the 64 kB devices. C8051F500/1/2/3/8/9 0xFFFF Reserved Area 0xFC00 Lock Byte 0xFBFF n 0xFBFE d i Lock Byte Page e z 0xFA00 nis ae C8051F504/5/6/7-F510/1 gg ra op Lock Byte 0x7FFF ory yte mb 0x7FFE e2- Flash Memory Space Lock Byte Page H m51 (64kB Flash Device) 0x7E00 S A L F Flash Memory Space (32kB Flash Device) 0x0000 0x0000 Figure 12.2. Flash Program Memory Map 12.1.1. MOVX Instruction and Program Memory The MOVX instruction in an 8051 device is typically used to access external data memory. On the C8051F50x/F51x devices, the MOVX instruction is normally used to read and write on-chip XRAM, but can be re-configured to write and erase on-chip Flash memory space. MOVC instructions are always used to read Flash memory, while MOVX write instructions are used to erase and write Flash. This Flash access feature provides a mechanism for the C8051F50x/F51x to update program code and use the program memory space for non-volatile data storage. Refer to Section “15. Flash Memory” on page 129 for further details. 12.2. Data Memory The C8051F50x/F51x devices include 4352 bytes of RAM data memory. 256 bytes of this memory is mapped into the internal RAM space of the 8051. The other 4096 bytes of this memory is on-chip “exter- nal” memory. The data memory map is shown in Figure 12.1 for reference. 12.2.1. Internal RAM There are 256 bytes of internal RAM mapped into the data memory space from 0x00 through 0xFF. The lower 128 bytes of data memory are used for general purpose registers and scratch pad memory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight 98 Rev. 1.2

C8051F50x/F51x byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as bytes or as 128 bit locations accessible with the direct addressing mode. The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the same address space as the Special Function Registers (SFR) but is physically separate from the SFR space. The addressing mode used by an instruction when accessing locations above 0x7F determines whether the CPU accesses the upper 128 bytes of data memory space or the SFRs. Instructions that use direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the upper 128 bytes of data memory. Figure 12.1 illustrates the data memory organization of the C8051F50x/F51x. 12.2.1.1. General Purpose Registers The lower 32 bytes of data memory, locations 0x00 through 0x1F, may be addressed as four banks of gen- eral-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7. Only one of these banks may be enabled at a time. Two bits in the program status word, RS0 (PSW.3) and RS1 (PSW.4), select the active register bank (see description of the PSW in SFR Definition 11.6). This allows fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes use registers R0 and R1 as index registers. 12.2.1.2. Bit Addressable Locations In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20 through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from 0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit7 of the byte at 0x20 has bit address 0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by the type of instruction used (bit source or destination operands as opposed to a byte source or destina- tion). The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B where XX is the byte address and B is the bit position within the byte. For example, the instruction: MOV C, 22.3h moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag. 12.2.1.3. Stack A programmer's stack can be located anywhere in the 256-byte data memory. The stack area is desig- nated using the Stack Pointer (SP) SFR. The SP will point to the last location used. The next value pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to location 0x07. Therefore, the first value pushed on the stack is placed at location 0x08, which is also the first regis- ter (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be initialized to a location in the data memory not being used for data storage. The stack depth can extend up to 256 bytes. Rev. 1.2 99

C8051F50x/F51x 13. Special Function Registers The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers (SFRs). The SFRs provide control and data exchange with the C8051F50x/F51x's resources and peripher- als. The CIP-51 controller core duplicates the SFRs found in a typical 8051 implementation as well as implementing additional SFRs used to configure and access the sub-systems unique to the C8051F50x/F51x. This allows the addition of new functionality while retaining compatibility with the MCS- 51™ instruction set. Table 13.3 lists the SFRs implemented in the C8051F50x/F51x device family. The SFR registers are accessed anytime the direct addressing mode is used to access memory locations from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g., P0, TCON, SCON0, IE, etc.) are bit- addressable as well as byte-addressable. All other SFRs are byte-addressable only. Unoccupied addresses in the SFR space are reserved for future use. Accessing unoccupied addresses in the SFR space will have an indeterminate effect and should be avoided. Refer to the corresponding pages of the data sheet, as indicated in Table 13.3, for a detailed description of each register. 13.1. SFR Paging The CIP-51 features SFR paging, allowing the device to map many SFRs into the 0x80 to 0xFF memory address space. The SFR memory space has 256 pages. In this way, each memory location from 0x80 to 0xFF can access up to 256 SFRs. The C8051F50x/F51x family of devices utilizes three SFR pages: 0x0, 0xC, and 0xF. SFR pages are selected using the Special Function Register Page Selection register, SFRP- AGE (see SFR Definition 11.3). The procedure for reading and writing an SFR is as follows: 1. Select the appropriate SFR page number using the SFRPAGE register. 2. Use direct accessing mode to read or write the special function register (MOV instruction). 13.2. Interrupts and SFR Paging When an interrupt occurs, the SFR Page Register will automatically switch to the SFR page containing the flag bit that caused the interrupt. The automatic SFR Page switch function conveniently removes the bur- den of switching SFR pages from the interrupt service routine. Upon execution of the RETI instruction, the SFR page is automatically restored to the SFR Page in use prior to the interrupt. This is accomplished via a three-byte SFR Page Stack. The top byte of the stack is SFRPAGE, the current SFR Page. The second byte of the SFR Page Stack is SFRNEXT. The third, or bottom byte of the SFR Page Stack is SFRLAST. Upon an interrupt, the current SFRPAGE value is pushed to the SFRNEXT byte, and the value of SFRNEXT is pushed to SFRLAST. Hardware then loads SFRPAGE with the SFR Page containing the flag bit associated with the interrupt. On a return from interrupt, the SFR Page Stack is popped resulting in the value of SFRNEXT returning to the SFRPAGE register, thereby restoring the SFR page context without software intervention. The value in SFRLAST (0x00 if there is no SFR Page value in the bottom of the stack) of the stack is placed in SFRNEXT register. If desired, the values stored in SFRNEXT and SFR- LAST may be modified during an interrupt, enabling the CPU to return to a different SFR Page upon exe- cution of the RETI instruction (on interrupt exit). Modifying registers in the SFR Page Stack does not cause a push or pop of the stack. Only interrupt calls and returns will cause push/pop operations on the SFR Page Stack. On the C8051F50x/F51x devices, vectoring to an interrupt will switch SFRPAGE to page 0x00, except for the CAN0 interrupt which will switch SFRPAGE to page 0x0C. Rev. 1.2 100

C8051F50x/F51x SFRPGCN Bit Interrupt Logic SFRPAGE CIP-51 SFRNEXT SFRLAST Figure 13.1. SFR Page Stack Automatic hardware switching of the SFR Page on interrupts may be enabled or disabled as desired using the SFR Automatic Page Control Enable Bit located in the SFR Page Control Register (SFR0CN). This function defaults to “enabled” upon reset. In this way, the autoswitching function will be enabled unless dis- abled in software. A summary of the SFR locations (address and SFR page) are provided in Table 13.3 in the form of an SFR memory map. Each memory location in the map has an SFR page row, denoting the page in which that SFR resides. Certain SFRs are accessible from ALL SFR pages, and are denoted by the “(ALL PAGES)” designation. For example, the Port I/O registers P0, P1, P2, and P3 all have the “(ALL PAGES)” designa- tion, indicating these SFRs are accessible from all SFR pages regardless of the SFRPAGE register value. 13.3. SFR Page Stack Example The following is an example that shows the operation of the SFR Page Stack during interrupts. In this example, the SFR Control register is left in the default enabled state (i.e., SFRPGEN = 1), and the CIP-51 is executing in-line code that is writing values to SPI Data Register (SFR “SPI0DAT”, located at address 0xA3 on SFR Page 0x00). The device is also using the CAN peripheral (CAN0) and the Programmable Counter Array (PCA0) peripheral to generate a PWM output. The PCA is timing a critical control function in its interrupt service round so its associated ISR that is set to low priority. At this point, the SFR page is set to access the SPI0DAT SFR (SFRPAGE = 0x00). See Figure 13.2. 101 Rev. 1.2

C8051F50x/F51x SFR Page Stack SFR's 0x0 SFRPAGE (SPI0DAT) SFRNEXT SFRLAST Figure 13.2. SFR Page Stack While Using SFR Page 0x0 To Access SPI0DAT While CIP-51 executes in-line code (writing values to SPI0DAT in this example), the CAN0 Interrupt occurs. The CIP-51 vectors to the CAN0 ISR and pushes the current SFR Page value (SFR Page 0x00) into SFRNEXT in the SFR Page Stack. The SFR page needed to access CAN’s SFRs is then automatically placed in the SFRPAGE register (SFR Page 0x0C). SFRPAGE is considered the “top” of the SFR Page Stack. Software can now access the CAN0 SFRs. Software may switch to any SFR Page by writing a new value to the SFRPAGE register at any time during the CAN0 ISR to access SFRs that are not on SFR Page 0x0C. See Figure 13.3. Rev. 1.2 102

C8051F50x/F51x SFR Page 0xC Automatically pushed on stack in SFRPAGE on CAN0 interrupt 0xC SFRPAGE (CAN0) SFRPAGE pushed to 0x0 SFRNEXT SFRNEXT (SPI0DAT) SFRLAST Figure 13.3. SFR Page Stack After CAN0 Interrupt Occurs While in the CAN0 ISR, a PCA interrupt occurs. Recall the PCA interrupt is configured as a high priority interrupt, while the CAN0 interrupt is configured as a low priority interrupt. Thus, the CIP-51 will now vector to the high priority PCA ISR. Upon doing so, the CIP-51 will automatically place the SFR page needed to access the PCA’s special function registers into the SFRPAGE register, SFR Page 0x00. The value that was in the SFRPAGE register before the PCA interrupt (SFR Page 0x0C for CAN0) is pushed down the stack into SFRNEXT. Likewise, the value that was in the SFRNEXT register before the PCA interrupt (in this case SFR Page 0x00 for SPI0DAT) is pushed down to the SFRLAST register, the “bottom” of the stack. Note that a value stored in SFRLAST (via a previous software write to the SFRLAST register) will be overwritten. See Figure 13.4. 103 Rev. 1.2

C8051F50x/F51x SFR Page 0x0 Automatically pushed on stack in SFRPAGE on PCA interrupt 0x0 SFRPAGE (PCA) SFRPAGE pushed to 0xC SFRNEXT SFRNEXT (CAN0) SFRNEXT pushed to 0x0 SFRLAST SFRLAST (SPI0DAT) Figure 13.4. SFR Page Stack Upon PCA Interrupt Occurring During a CAN0 ISR On exit from the PCA interrupt service routine, the CIP-51 will return to the CAN0 ISR. On execution of the RETI instruction, SFR Page 0x00 used to access the PCA registers will be automatically popped off of the SFR Page Stack, and the contents of the SFRNEXT register will be moved to the SFRPAGE register. Soft- ware in the CAN0 ISR can continue to access SFRs as it did prior to the PCA interrupt. Likewise, the con- tents of SFRLAST are moved to the SFRNEXT register. Recall this was the SFR Page value 0x00 being used to access SPI0DAT before the CAN0 interrupt occurred. See Figure 13.5. Rev. 1.2 104

C8051F50x/F51x SFR Page 0x0 Automatically popped off of the stack on return from interrupt 0xC SFRPAGE (CAN0) SFRNEXT popped to 0x0 SFRPAGE SFRNEXT (SPI0DAT) SFRLAST popped to SFRNEXT SFRLAST Figure 13.5. SFR Page Stack Upon Return From PCA Interrupt On the execution of the RETI instruction in the CAN0 ISR, the value in SFRPAGE register is overwritten with the contents of SFRNEXT. The CIP-51 may now access the SPI0DAT register as it did prior to the interrupts occurring. See Figure 13.6. 105 Rev. 1.2

C8051F50x/F51x SFR Page 0xC Automatically popped off of the stack on return from interrupt 0x0 SFRPAGE (SPI0DAT) SFRNEXT popped to SFRPAGE SFRNEXT SFRLAST Figure 13.6. SFR Page Stack Upon Return From CAN0 Interrupt In the example above, all three bytes in the SFR Page Stack are accessible via the SFRPAGE, SFRNEXT, and SFRLAST special function registers. If the stack is altered while servicing an interrupt, it is possible to return to a different SFR Page upon interrupt exit than selected prior to the interrupt call. Direct access to the SFR Page stack can be useful to enable real-time operating systems to control and manage context switching between multiple tasks. Push operations on the SFR Page Stack only occur on interrupt service, and pop operations only occur on interrupt exit (execution on the RETI instruction). The automatic switching of the SFRPAGE and operation of the SFR Page Stack as described above can be disabled in software by clearing the SFR Automatic Page Enable Bit (SFRPGEN) in the SFR Page Control Register (SFR0CN). See SFR Definition 13.1. Rev. 1.2 106

C8051F50x/F51x SFR Definition 13.1. SFR0CN: SFR Page Control Bit 7 6 5 4 3 2 1 0 Name SFRPGEN Type R R R R R R R R/W Reset 0 0 0 0 0 0 0 1 SFR Address = 0x84; SFR Page = 0x0F Bit Name Function 7:1 Unused Read = 0000000b; Write = Don’t Care 0 SFRPGEN SFR Automatic Page Control Enable. Upon interrupt, the C8051 Core will vector to the specified interrupt service routine and automatically switch the SFR page to the corresponding peripheral or function’s SFR page. This bit is used to control this autopaging function. 0: SFR Automatic Paging disabled. The C8051 core will not automatically change to the appropriate SFR page (i.e., the SFR page that contains the SFRs for the periph- eral/function that was the source of the interrupt). 1: SFR Automatic Paging enabled. Upon interrupt, the C8051 will switch the SFR page to the page that contains the SFRs for the peripheral or function that is the source of the interrupt. 107 Rev. 1.2

C8051F50x/F51x SFR Definition 13.2. SFRPAGE: SFR Page Bit 7 6 5 4 3 2 1 0 Name SFRPAGE[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xA7; SFR Page = All Pages Bit Name Function 7:0 SFRPAGE[7:0] SFR Page Bits. Represents the SFR Page the C8051 core uses when reading or modifying SFRs. Write: Sets the SFR Page. Read: Byte is the SFR page the C8051 core is using. When enabled in the SFR Page Control Register (SFR0CN), the C8051 core will automatically switch to the SFR Page that contains the SFRs of the correspond- ing peripheral/function that caused the interrupt, and return to the previous SFR page upon return from interrupt (unless SFR Stack was altered before a return- ing from the interrupt). SFRPAGE is the top byte of the SFR Page Stack, and push/pop events of this stack are caused by interrupts (and not by reading/writ- ing to the SFRPAGE register) Rev. 1.2 108

C8051F50x/F51x SFR Definition 13.3. SFRNEXT: SFR Next Bit 7 6 5 4 3 2 1 0 Name SFRNEXT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x85; SFR Page = All Pages Bit Name Function 7:0 SFRNEXT[7:0] SFR Page Bits. This is the value that will go to the SFR Page register upon a return from inter- rupt. Write: Sets the SFR Page contained in the second byte of the SFR Stack. This will cause the SFRPAGE SFR to have this SFR page value upon a return from interrupt. Read: Returns the value of the SFR page contained in the second byte of the SFR stack. SFR page context is retained upon interrupts/return from interrupts in a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFRLAST is the third entry. The SFR stack bytes may be used alter the context in the SFR Page Stack, and will not cause the stack to “push” or “pop”. Only interrupts and return from interrupts cause pushes and pops of the SFR Page Stack. 109 Rev. 1.2

C8051F50x/F51x SFR Definition 13.4. SFRLAST: SFR Last Bit 7 6 5 4 3 2 1 0 Name SFRLAST[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xA7; SFR Page = All Pages Bit Name Function 7:0 SFRLAST[7:0] SFR Page Stack Bits. This is the value that will go to the SFRNEXT register upon a return from inter- rupt. Write: Sets the SFR Page in the last entry of the SFR Stack. This will cause the SFRNEXT SFR to have this SFR page value upon a return from interrupt. Read: Returns the value of the SFR page contained in the last entry of the SFR stack. SFR page context is retained upon interrupts/return from interrupts in a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFRLAST is the third entry. The SFR stack bytes may be used alter the context in the SFR Page Stack, and will not cause the stack to “push” or “pop”. Only interrupts and return from interrupts cause pushes and pops of the SFR Page Stack. Rev. 1.2 110

C8051F50x/F51x Table 13.1. Special Function Register (SFR) Memory Map for Pages 0x0 and 0xF s 0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F) s e e g dr a d P A F8 0 SPI0CN PCA0L PCA0H PCA0CPL0 PCA0CPH0 PCACPL4 PCACPH4 VDM0CN F SN0 SN1 SN2 SN3 F0 0 B P0MAT P0MASK P1MAT P1MASK EIP1 EIP2 F(All Pages) P0MDIN P1MDIN P2MDIN P3MDIN EIP1 EIP2 E8 0 ADC0CN PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2 PCA0CPL3 PCA0CPL3 RSTSRC F E0 0 ACC EIE1 EIE2 F(All Pages) XBR0 XBR1 CCH0CN IT01CF (All Pages) (All Pages) D80 PCA0CN PCA0MD PCA0CPM0PCA0CPM1PCA0CPM2PCA0CPM3PCA0CPM4PCA0CPM5 F PCA0PWM D00 PSW REF0CN LIN0DATA LIN0ADDR F(All Pages) P0SKIP P1SKIP P2SKIP P3SKIP C80 TMR2CN REG0CN TMR2RLL TMR2RLH TMR2L TMR2H PCA0CPL5 PCA0CPH5 F LIN0CF C00 SMB0CN SMB0CF SMB0DAT ADC0GTL ADC0GTH ADC0LTL ADC0LTH F XBR2 B8 0 IP ADC0TK ADC0MX ADC0CF ADC0L ADC0H F(All Pages) B0 0 P3 P2MAT P2MASK P4 FLSCL FLKEY F(All Pages) EMI0CF (All Pages) (All Pages) (All Pages) A8 0 IE SMOD0 EMI0CN P3MAT P3MASK F(All Pages) EMI0TC SBCON0 SBRLL0 SBRLH0 P3MDOUT P4MDOUT A0 0 P2 SPI0CFG SPI0CKR SPI0DAT SFRPAGE F(All Pages) OSCICN OSCICRS P0MDOUT P1MDOUT P2MDOUT (All Pages) 98 0 SCON0 SBUF0 CPT0CN CPT0MD CPT0MX CPT1CN CPT1MD CPT1MX F OSCIFIN OSCXCN 90 0 P1 TMR3CN TMR3RLL TMR3RLH TMR3L TMR3H F(All Pages) CLKMUL 88 0 TCON TMOD TL0 TL1 TH0 TH1 CKCON PSCTL F(All Pages) (All Pages) (All Pages) (All Pages) (All Pages) (All Pages) (All Pages) CLKSEL 80 0 P0 SP DPL DPH SFRNEXT SFRLAST PCON F(All Pages) (All Pages) (All Pages) (All Pages) SFR0CN (All Pages) (All Pages) (All Pages) 0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F) (bit addressable) 111 Rev. 1.2

C8051F50x/F51x Table 13.2. Special Function Register (SFR) Memory Map for Page 0xC 0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F) F8 CAN0IF2DA2L CAN0IF2DA2H CAN0IF2DB1L CAN0IF2DB1H CAN0IF2DB2L CAN0IF2DB2H F0 B CAN0IF2A2L CAN0IF2A2H CAN0IF2DA1L CAN0IF2DA1H (All Pages) E8 CAN0IF2M1L CAN0IF2M1H CAN0IF2M2L CAN0IF2M2H CAN0IF2A1L CAN0IF2A1H E0 ACC CAN0IF2CML CAN0IF2CMH EIE1 EIE2 (All Pages) (All Pages) (All Pages) D8 CAN0IF1DB1L CAN0IF1DB1H CAN0IF1DB2L CAN0IF1DB2H CAN0IF2CRL CAN0IF2CRH D0 PSW CAN0IF1MCL CAN0IF1MCH CAN0IF1DA1L CAN0IF1DA1H CAN0IF1DA2L CAN0IF1DA2H (All Pages) C8 CAN0IF1A1L CAN0IF1A1H CAN0IF1A2L CAN0IF1A2H CAN0IF2MCL CAN0IF2MCH C0 CAN0CN CAN0IF1CML CAN0IF1CMH CAN0IF1M1L CAN0IF1M1H CAN0IF1M2L CAN0IF1M2H B8 IP CAN0MV1L CAN0MV1H CAN0MV2L CAN0MV2H CAN0IF1CRL CAN0IF1CRH (All Pages) B0 P3 CAN0IP2L CAN0IP2H P4 FLSCL FLKEY (All Pages) (All Pages) (All Pages) (All Pages) A8 IE CAN0ND1L CAN0ND1H CAN0ND2L CAN0ND2H CAN0IP1L CAN0IP1H (All Pages) A0 P2 CAN0BRPE CAN0TR1L CAN0TR1H CAN0TR2L CAN0TR2H SFRPAGE (All Pages) (All Pages) 98 SCON0 CAN0BTL CAN0BTH CAN0IIDL CAN0IIDH CAN0TST (All Pages) 90 P1 CAN0CFG CAN0STAT CAN0ERRL CAN0ERRH (All Pages) 88 TCON TMOD TL0 TL1 TH0 TH1 CKCON (All Pages) (All Pages) (All Pages) (All Pages) (All Pages) (All Pages) (All Pages) 80 P0 SP DPL DPH SFRNEXT SFRLAST PCON (All Pages) (All Pages) (All Pages) (All Pages) (All Pages) (All Pages) (All Pages) 0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F) (bit addressable) Rev. 1.2 112

C8051F50x/F51x Table 13.3. Special Function Registers SFRs are listed in alphabetical order. All undefined SFR locations are reserved Register Address Description Page ACC 0xE0 Accumulator 94 ADC0CF 0xBC ADC0 Configuration 63 ADC0CN 0xE8 ADC0 Control 65 ADC0GTH 0xC4 ADC0 Greater-Than Compare High 67 ADC0GTL 0xC3 ADC0 Greater-Than Compare Low 67 ADC0H 0xBE ADC0 High 64 ADC0L 0xBD ADC0 Low 64 ADC0LTH 0xC6 ADC0 Less-Than Compare Word High 68 ADC0LTL 0xC5 ADC0 Less-Than Compare Word Low 68 ADC0MX 0xBB ADC0 Mux Configuration 71 ADC0TK 0xBA ADC0 Tracking Mode Select 66 B 0xF0 B Register 94 CCH0CN 0xE3 Cache Control 137 CKCON 0x8E Clock Control 266 CLKMUL 0x97 Clock Multiplier 171 CLKSEL 0x8F Clock Select 166 CPT0CN 0x9A Comparator0 Control 77 CPT0MD 0x9B Comparator0 Mode Selection 78 CPT0MX 0x9C Comparator0 MUX Selection 82 CPT1CN 0x9D Comparator1 Control 77 CPT1MD 0x9E Comparator1 Mode Selection 78 CPT1MX 0x9F Comparator1 MUX Selection 82 DPH 0x83 Data Pointer High 93 DPL 0x82 Data Pointer Low 93 EIE1 0xE6 Extended Interrupt Enable 1 123 EIE2 0xE7 Extended Interrupt Enable 2 123 EIP1 0xF6 Extended Interrupt Priority 1 124 EIP2 0xF7 Extended Interrupt Priority 2 125 EMI0CF 0xB2 External Memory Interface Configuration 152 EMI0CN 0xAA External Memory Interface Control 151 EMI0TC 0xAA External Memory Interface Timing Control 157 FLKEY 0xB7 Flash Lock and Key 135 FLSCL 0xB6 Flash Scale 136 IE 0xA8 Interrupt Enable 121 IP 0xB8 Interrupt Priority 122 113 Rev. 1.2

C8051F50x/F51x Table 13.3. Special Function Registers (Continued) SFRs are listed in alphabetical order. All undefined SFR locations are reserved Register Address Description Page IT01CF 0xE4 INT0/INT1 Configuration 128 LIN0ADR 0xD3 LIN0 Address 208 LIN0CF 0xC9 LIN0 Configuration 208 LIN0DAT 0xD2 LIN0 Data 209 OSCICN 0xA1 Internal Oscillator Control 168 OSCICRS 0xA2 Internal Oscillator Coarse Control 169 OSCIFIN 0x9E Internal Oscillator Fine Calibration 169 OSCXCN 0x9F External Oscillator Control 173 P0 0x80 Port 0 Latch 191 P0MASK 0xF2 Port 0 Mask Configuration 187 P0MAT 0xF1 Port 0 Match Configuration 187 P0MDIN 0xF1 Port 0 Input Mode Configuration 192 P0MDOUT 0xA4 Port 0 Output Mode Configuration 192 P0SKIP 0xD4 Port 0 Skip 193 P1 0x90 Port 1 Latch 193 P1MASK 0xF4 Port 1 Mask Configuration 188 P1MAT 0xF3 Port 1 Match Configuration 188 P1MDIN 0xF2 Port 1 Input Mode Configuration 194 P1MDOUT 0xA5 Port 1 Output Mode Configuration 194 P1SKIP 0xD5 Port 1 Skip 195 P2 0xA0 Port 2 Latch 195 P2MASK 0xB2 Port 2 Mask Configuration 189 P2MAT 0xB1 Port 2 Match Configuration 189 P2MDIN 0xF3 Port 2 Input Mode Configuration 196 P2MDOUT 0xA6 Port 2 Output Mode Configuration 196 P2SKIP 0xD6 Port 2 Skip 197 P3 0xB0 Port 3 Latch 197 P3MASK 0xAF Port 3 Mask Configuration 190 P3MAT 0xAE Port 3 Match Configuration 190 P3MDIN 0xF4 Port 3 Input Mode Configuration 198 P3MDOUT 0xAE Port 3 Output Mode Configuration 198 P3SKIP 0xD7 Port 3 Skip 199 P4 0xB5 Port 4 Latch 199 P4MDOUT 0xAF Port 4 Output Mode Configuration 200 PCA0CN 0xD8 PCA Control 300 PCA0CPH0 0xFC PCA Capture 0 High 305 Rev. 1.2 114

C8051F50x/F51x Table 13.3. Special Function Registers (Continued) SFRs are listed in alphabetical order. All undefined SFR locations are reserved Register Address Description Page PCA0CPH1 0xEA PCA Capture 1 High 305 PCA0CPH2 0xEC PCA Capture 2 High 305 PCA0CPH3 0xEE PCA Capture 3 High 305 PCA0CPH4 0xFE PCA Capture 4 High 305 PCA0CPH5 0xCF PCA Capture 5 High 305 PCA0CPL0 0xFB PCA Capture 0 Low 305 PCA0CPL1 0xE9 PCA Capture 1 Low 305 PCA0CPL2 0xEB PCA Capture 2 Low 305 PCA0CPL3 0xED PCA Capture 3 Low 305 PCA0CPL4 0xFD PCA Capture 4 Low 305 PCA0CPL5 0xCE PCA Capture 5 Low 305 PCA0CPM0 0xDA PCA Module 0 Mode Register 303 PCA0CPM1 0xDB PCA Module 1 Mode Register 303 PCA0CPM2 0xDC PCA Module 2 Mode Register 303 PCA0CPM3 0xDD PCA Module 3 Mode Register 303 PCA0CPM4 0xDE PCA Module 4 Mode Register 303 PCA0CPM5 0xDF PCA Module 5 Mode Register 303 PCA0H 0xFA PCA Counter High 304 PCA0L 0xF9 PCA Counter Low 304 PCA0MD 0xD9 PCA Mode 301 PCA0PWM 0xD9 PCA PWM Configuration 302 PCON 0x87 Power Control 140 PSCTL 0x8F Program Store R/W Control 134 PSW 0xD0 Program Status Word 95 REF0CN 0xD1 Voltage Reference Control 74 REG0CN 0xD1 Voltage Regulator Control 85 RSTSRC 0xEF Reset Source Configuration/Status 146 SBCON0 0xAB UART0 Baud Rate Generator Control 250 SBRLH0 0xAD UART0 Baud Rate Reload High Byte 251 SBRLL0 0xAC UART0 Baud Rate Reload Low Byte 251 SBUF0 0x99 UART0 Data Buffer 250 SCON0 0x98 UART0 Control 248 SFR0CN 0x84 SFR Page Control 107 SFRLAST 0x86 SFR Stack Last Page 110 SFRNEXT 0x85 SFR Stack Next Page 109 SFRPAGE 0xA7 SFR Page Select 108 115 Rev. 1.2

C8051F50x/F51x Table 13.3. Special Function Registers (Continued) SFRs are listed in alphabetical order. All undefined SFR locations are reserved Register Address Description Page SMB0CF 0xC1 SMBus0 Configuration 232 SMB0CN 0xC0 SMBus0 Control 234 SMB0DAT 0xC2 SMBus0 Data 236 SMOD0 0xA9 UART0 Mode 249 SN0 - SN3 0xF9 - 0xFC Serial Number Registers 96 SP 0x81 Stack Pointer 94 SPI0CFG 0xA1 SPI0 Configuration 259 SPI0CKR 0xA2 SPI0 Clock Rate Control 261 SPI0CN 0xF8 SPI0 Control 260 SPI0DAT 0xA3 SPI0 Data 261 TCON 0x88 Timer/Counter Control 271 TH0 0x8C Timer/Counter 0 High 274 TH1 0x8D Timer/Counter 1 High 274 TL0 0x8A Timer/Counter 0 Low 273 TL1 0x8B Timer/Counter 1 Low 273 TMOD 0x89 Timer/Counter Mode 272 TMR2CN 0xC8 Timer/Counter 2 Control 278 TMR2H 0xCD Timer/Counter 2 High 280 TMR2L 0xCC Timer/Counter 2 Low 280 TMR2RLH 0xCB Timer/Counter 2 Reload High 279 TMR2RLL 0xCA Timer/Counter 2 Reload Low 279 TMR3CN 0x91 Timer/Counter 3 Control 284 TMR3H 0x95 Timer/Counter 3 High 286 TMR3L 0x94 Timer/Counter 3 Low 286 TMR3RLH 0x93 Timer/Counter 3 Reload High 285 TMR3RLL 0x92 Timer/Counter 3 Reload Low 285 VDM0CN 0xFF V Monitor Control 144 DD XBR0 0xE1 Port I/O Crossbar Control 0 184 XBR1 0xE2 Port I/O Crossbar Control 1 185 XBR2 0xC7 Port I/O Crossbar Control 2 186 Note: The CAN registers are not explicitly defined in this datasheet. See Table 22.2 on page 223 for the list of all available CAN registers. Rev. 1.2 116

C8051F50x/F51x 14. Interrupts The C8051F50x/F51x devices include an extended interrupt system supporting a total of 18 interrupt sources with two priority levels. The allocation of interrupt sources between on-chip peripherals and exter- nal inputs pins varies according to the specific version of the device. Each interrupt source has one or more associated interrupt-pending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition, the associated interrupt-pending flag is set to logic 1. If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a prede- termined address to begin execution of an interrupt service routine (ISR). Each ISR must end with an RETI instruction, which returns program execution to the next instruction that would have been executed if the interrupt request had not occurred. If interrupts are not enabled, the interrupt-pending flag is ignored by the hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regard- less of the interrupt's enable/disable state.) Each interrupt source can be individually enabled or disabled through the use of an associated interrupt enable bit in an SFR (IE, EIE1, or EIE2). However, interrupts must first be globally enabled by setting the EA bit (IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0 disables all interrupt sources regardless of the individual interrupt-enable settings. Note: Any instruction that clears a bit to disable an interrupt should be immediately followed by an instruction that has two or more opcode bytes. Using EA (global interrupt enable) as an example: // in 'C': EA = 0; // clear EA bit. EA = 0; // this is a dummy instruction with two-byte opcode. ; in assembly: CLR EA ; clear EA bit. CLR EA ; this is a dummy instruction with two-byte opcode. For example, if an interrupt is posted during the execution phase of a "CLR EA" opcode (or any instruction which clears a bit to disable an interrupt source), and the instruction is followed by a single-cycle instruc- tion, the interrupt may be taken. However, a read of the enable bit will return a 0 inside the interrupt service routine. When the bit-clearing opcode is followed by a multi-cycle instruction, the interrupt will not be taken. Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR. However, most are not cleared by the hardware and must be cleared by software before returning from the ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI) instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after the completion of the next instruction. 14.1. MCU Interrupt Sources and Vectors The C8051F50x/F51x MCUs support 18 interrupt sources. Software can simulate an interrupt by setting any interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be gener- ated and the CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources, associated vector addresses, priority order and control bits are summarized in Table 14.1. Refer to the datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s). Rev. 1.2 117

C8051F50x/F51x 14.1.1. Interrupt Priorities Each interrupt source can be individually programmed to one of two priority levels: low or high. A low prior- ity interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be preempted. Each interrupt has an associated interrupt priority bit in an SFR (IE, EIP1, or EIP2) used to configure its priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with the higher priority is serviced first. If both interrupts have the same priority level, a fixed prior- ity order is used to arbitrate, given in Table 14.1. 14.1.2. Interrupt Latency Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 5 system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is 18 system clock cycles: 1 clock cycle to detect the interrupt, 5 clock cycles to execute the RETI, 8 clock cycles to complete the DIV instruction and 4 clock cycles to execute the LCALL to the ISR. If the CPU is executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the current ISR completes, including the RETI and following instruction. 118 Rev. 1.2

C8051F50x/F51x Table 14.1. Interrupt Summary Interrupt Source Interrupt Priority Pending Flag ? ? Enable Priority e W Vector Order bl Flag Control H a s y s b re d d e d r a a Bit Cle Reset 0x0000 Top None N/A N/A Always Always Enabled Highest External Interrupt 0 0x0003 0 IE0 (TCON.1) Y Y EX0 (IE.0) PX0 (IP.0) (INT0) Timer 0 Overflow 0x000B 1 TF0 (TCON.5) Y Y ET0 (IE.1) PT0 (IP.1) External Interrupt 1 0x0013 2 IE1 (TCON.3) Y Y EX1 (IE.2) PX1 (IP.2) (INT1) Timer 1 Overflow 0x001B 3 TF1 (TCON.7) Y Y ET1 (IE.3) PT1 (IP.3) UART0 0x0023 4 RI0 (SCON0.0) Y N ES0 (IE.4) PS0 (IP.4) TI0 (SCON0.1) Timer 2 Overflow 0x002B 5 TF2H (TMR2CN.7) Y N ET2 (IE.5) PT2 (IP.5) TF2L (TMR2CN.6) SPI0 0x0033 6 SPIF (SPI0CN.7) Y N ESPI0 PSPI0 WCOL (SPI0CN.6) (IE.6) (IP.6) MODF (SPI0CN.5) RXOVRN (SPI0CN.4) SMB0 0x003B 7 SI (SMB0CN.0) Y N ESMB0 PSMB0 (EIE1.0) (EIP1.0) ADC0 Window Com- 0x0043 8 AD0WINT Y N EWADC0 PWADC0 pare (ADC0CN.3) (EIE1.1) (EIP1.1) ADC0 Conversion 0x004B 9 AD0INT (ADC0CN.5) Y N EADC0 PADC0 Complete (EIE1.2) (EIP1.2) Programmable 0x0053 10 CF (PCA0CN.7) Y N EPCA0 PPCA0 Counter Array CCFn (PCA0CN.n) (EIE1.3) (EIP1.3) COVF (PCA0PWM.6) Comparator0 0x005B 11 CP0FIF (CPT0CN.4) N N ECP0 PCP0 CP0RIF (CPT0CN.5) (EIE1.4) (EIP1.4) Comparator1 0x0063 12 CP1FIF (CPT1CN.4) N N ECP1 PCP1 CP1RIF (CPT1CN.5) (EIE1.5) (EIP1.5) Timer 3 Overflow 0x006B 13 TF3H (TMR3CN.7) N N ET3 PT3 TF3L (TMR3CN.6) (EIE1.6) (EIP1.6) LIN0 0x0073 14 LIN0INT (LINST.3) N N* ELIN0 PLIN0 (EIE1.7) (EIP1.7) Voltage Regulator 0x007B 15 N/A N/A N/A EREG0 PREG0 Dropout (EIE2.0) (EIP2.0) CAN0 0x0083 16 CAN0INT N Y ECAN0 PCAN0 (CAN0CN.7) (EIE2.1) (EIP2.1) Port Match 0x008B 17 None N/A N/A EMAT PMAT (EIE2.2) (EIP2.2) Note: The LIN0INT bit is cleared by setting RSTINT (LINCTRL.3) Rev. 1.2 119

C8051F50x/F51x 14.2. Interrupt Register Descriptions The SFRs used to enable the interrupt sources and set their priority level are described in this section. Refer to the data sheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s). 120 Rev. 1.2

C8051F50x/F51x SFR Definition 14.1. IE: Interrupt Enable Bit 7 6 5 4 3 2 1 0 Name EA ESPI0 ET2 ES0 ET1 EX1 ET0 EX0 Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xA8; Bit-Addressable; SFR Page = All Pages Bit Name Function 7 EA Enable All Interrupts. Globally enables/disables all interrupts. It overrides individual interrupt mask settings. 0: Disable all interrupt sources. 1: Enable each interrupt according to its individual mask setting. 6 ESPI0 Enable Serial Peripheral Interface (SPI0) Interrupt. This bit sets the masking of the SPI0 interrupts. 0: Disable all SPI0 interrupts. 1: Enable interrupt requests generated by SPI0. 5 ET2 Enable Timer 2 Interrupt. This bit sets the masking of the Timer 2 interrupt. 0: Disable Timer 2 interrupt. 1: Enable interrupt requests generated by the TF2L or TF2H flags. 4 ES0 Enable UART0 Interrupt. This bit sets the masking of the UART0 interrupt. 0: Disable UART0 interrupt. 1: Enable UART0 interrupt. 3 ET1 Enable Timer 1 Interrupt. This bit sets the masking of the Timer 1 interrupt. 0: Disable all Timer 1 interrupt. 1: Enable interrupt requests generated by the TF1 flag. 2 EX1 Enable External Interrupt 1. This bit sets the masking of External Interrupt 1. 0: Disable external interrupt 1. 1: Enable interrupt requests generated by the INT1 input. 1 ET0 Enable Timer 0 Interrupt. This bit sets the masking of the Timer 0 interrupt. 0: Disable all Timer 0 interrupt. 1: Enable interrupt requests generated by the TF0 flag. 0 EX0 Enable External Interrupt 0. This bit sets the masking of External Interrupt 0. 0: Disable external interrupt 0. 1: Enable interrupt requests generated by the INT0 input. Rev. 1.2 121

C8051F50x/F51x SFR Definition 14.2. IP: Interrupt Priority Bit 7 6 5 4 3 2 1 0 Name PSPI0 PT2 PS0 PT1 PX1 PT0 PX0 Type R R/W R/W R/W R/W R/W R/W R/W Reset 1 0 0 0 0 0 0 0 SFR Address = 0xB8; Bit-Addressable; SFR Page = All Pages Bit Name Function 7 Unused Read = 1b, Write = Don't Care. 6 PSPI0 Serial Peripheral Interface (SPI0) Interrupt Priority Control. This bit sets the priority of the SPI0 interrupt. 0: SPI0 interrupt set to low priority level. 1: SPI0 interrupt set to high priority level. 5 PT2 Timer 2 Interrupt Priority Control. This bit sets the priority of the Timer 2 interrupt. 0: Timer 2 interrupt set to low priority level. 1: Timer 2 interrupt set to high priority level. 4 PS0 UART0 Interrupt Priority Control. This bit sets the priority of the UART0 interrupt. 0: UART0 interrupt set to low priority level. 1: UART0 interrupt set to high priority level. 3 PT1 Timer 1 Interrupt Priority Control. This bit sets the priority of the Timer 1 interrupt. 0: Timer 1 interrupt set to low priority level. 1: Timer 1 interrupt set to high priority level. 2 PX1 External Interrupt 1 Priority Control. This bit sets the priority of the External Interrupt 1 interrupt. 0: External Interrupt 1 set to low priority level. 1: External Interrupt 1 set to high priority level. 1 PT0 Timer 0 Interrupt Priority Control. This bit sets the priority of the Timer 0 interrupt. 0: Timer 0 interrupt set to low priority level. 1: Timer 0 interrupt set to high priority level. 0 PX0 External Interrupt 0 Priority Control. This bit sets the priority of the External Interrupt 0 interrupt. 0: External Interrupt 0 set to low priority level. 1: External Interrupt 0 set to high priority level. 122 Rev. 1.2

C8051F50x/F51x SFR Definition 14.3. EIE1: Extended Interrupt Enable 1 Bit 7 6 5 4 3 2 1 0 Name ELIN0 ET3 ECP1 ECP0 EPCA0 EADC0 EWADC0 ESMB0 Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xE6; SFR Page = All Pages Bit Name Function 7 ELIN0 Enable LIN0 Interrupt. This bit sets the masking of the LIN0 interrupt. 0: Disable LIN0 interrupts. 1: Enable interrupt requests generated by the LIN0INT flag. 6 ET3 Enable Timer 3 Interrupt. This bit sets the masking of the Timer 3 interrupt. 0: Disable Timer 3 interrupts. 1: Enable interrupt requests generated by the TF3L or TF3H flags. 5 ECP1 Enable Comparator1 (CP1) Interrupt. This bit sets the masking of the CP1 interrupt. 0: Disable CP1 interrupts. 1: Enable interrupt requests generated by the CP1RIF or CP1FIF flags. 4 ECP0 Enable Comparator0 (CP0) Interrupt. This bit sets the masking of the CP0 interrupt. 0: Disable CP0 interrupts. 1: Enable interrupt requests generated by the CP0RIF or CP0FIF flags. 3 EPCA0 Enable Programmable Counter Array (PCA0) Interrupt. This bit sets the masking of the PCA0 interrupts. 0: Disable all PCA0 interrupts. 1: Enable interrupt requests generated by PCA0. 2 EADC0 Enable ADC0 Conversion Complete Interrupt. This bit sets the masking of the ADC0 Conversion Complete interrupt. 0: Disable ADC0 Conversion Complete interrupt. 1: Enable interrupt requests generated by the AD0INT flag. 1 EWADC0 Enable Window Comparison ADC0 Interrupt. This bit sets the masking of ADC0 Window Comparison interrupt. 0: Disable ADC0 Window Comparison interrupt. 1: Enable interrupt requests generated by ADC0 Window Compare flag (AD0WINT). 0 ESMB0 Enable SMBus (SMB0) Interrupt. This bit sets the masking of the SMB0 interrupt. 0: Disable all SMB0 interrupts. 1: Enable interrupt requests generated by SMB0. Rev. 1.2 123

C8051F50x/F51x SFR Definition 14.4. EIP1: Extended Interrupt Priority 1 Bit 7 6 5 4 3 2 1 0 Name PLIN0 PT3 PCP1 PCP0 PPCA0 PADC0 PWADC0 PSMB0 Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xF6; SFR Page = 0x00 and 0x0F Bit Name Function 7 PLIN0 LIN0 Interrupt Priority Control. This bit sets the priority of the LIN0 interrupt. 0: LIN0 interrupts set to low priority level. 1: LIN0 interrupts set to high priority level. 6 PT3 Timer 3 Interrupt Priority Control. This bit sets the priority of the Timer 3 interrupt. 0: Timer 3 interrupts set to low priority level. 1: Timer 3 interrupts set to high priority level. 5 PCP1 Comparator0 (CP1) Interrupt Priority Control. This bit sets the priority of the CP1 interrupt. 0: CP1 interrupt set to low priority level. 1: CP1 interrupt set to high priority level. 4 PCP0 Comparator0 (CP0) Interrupt Priority Control. This bit sets the priority of the CP0 interrupt. 0: CP0 interrupt set to low priority level. 1: CP0 interrupt set to high priority level. 3 PPCA0 Programmable Counter Array (PCA0) Interrupt Priority Control. This bit sets the priority of the PCA0 interrupt. 0: PCA0 interrupt set to low priority level. 1: PCA0 interrupt set to high priority level. 2 PADC0 ADC0 Conversion Complete Interrupt Priority Control. This bit sets the priority of the ADC0 Conversion Complete interrupt. 0: ADC0 Conversion Complete interrupt set to low priority level. 1: ADC0 Conversion Complete interrupt set to high priority level. 1 PWADC0 ADC0 Window Comparator Interrupt Priority Control. This bit sets the priority of the ADC0 Window interrupt. 0: ADC0 Window interrupt set to low priority level. 1: ADC0 Window interrupt set to high priority level. 0 PSMB0 SMBus (SMB0) Interrupt Priority Control. This bit sets the priority of the SMB0 interrupt. 0: SMB0 interrupt set to low priority level. 1: SMB0 interrupt set to high priority level. 124 Rev. 1.2

C8051F50x/F51x SFR Definition 14.5. EIE2: Extended Interrupt Enable 2 Bit 7 6 5 4 3 2 1 0 Name EMAT ECAN0 EREG0 Type R R R R R R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xE7; SFR Page = All Pages Bit Name Function 7:3 Unused Read = 00000b; Write = Don’t Care. 2 EMAT Enable Port Match Interrupt. This bit sets the masking of the Port Match interrupt. 0: Disable all Port Match interrupts. 1: Enable interrupt requests generated by a Port Match 1 ECAN0 Enable CAN0 Interrupts. This bit sets the masking of the CAN0 interrupt. 0: Disable all CAN0 interrupts. 1: Enable interrupt requests generated by CAN0. 0 EREG0 Enable Voltage Regulator Dropout Interrupt. This bit sets the masking of the Voltage Regulator Dropout interrupt. 0: Disable the Voltage Regulator Dropout interrupt. 1: Enable the Voltage Regulator Dropout interrupt. Rev. 1.2 125

C8051F50x/F51x SFR Definition 14.6. EIP2: Extended Interrupt Priority Enabled 2 Bit 7 6 5 4 3 2 1 0 Name PMAT PCAN0 PREG0 Type R R R R R R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xF7; SFR Page = 0x00 and 0x0F Bit Name Function 7:3 Unused Read = 00000b; Write = Don’t Care. 2 PMAT Port Match Interrupt Priority Control. This bit sets the priority of the Port Match interrupt. 0: Port Match interrupt set to low priority level. 1: Port Match interrupt set to high priority level. 1 PCAN0 CAN0 Interrupt Priority Control. This bit sets the priority of the CAN0 interrupt. 0: CAN0 interrupt set to low priority level. 1: CAN0 interrupt set to high priority level. 0 PREG0 Voltage Regulator Dropout Interrupt Priority Control. This bit sets the priority of the Voltage Regulator Dropout interrupt. 0: Voltage Regulator Dropout interrupt set to low priority level. 1: Voltage Regulator Dropout interrupt set to high priority level. 14.3. External Interrupts INT0 and INT1 The INT0 and INT1 external interrupt sources are configurable as active high or low, edge or level sensi- tive. The IN0PL (INT0 Polarity) and IN1PL (INT1 Polarity) bits in the IT01CF register select active high or active low; the IT0 and IT1 bits in TCON (Section “26.1. Timer 0 and Timer 1” on page 267) select level or edge sensitive. The table below lists the possible configurations. IT0 IN0PL INT0 Interrupt IT1 IN1PL INT1 Interrupt 1 0 Active low, edge sensitive 1 0 Active low, edge sensitive 1 1 Active high, edge sensitive 1 1 Active high, edge sensitive 0 0 Active low, level sensitive 0 0 Active low, level sensitive 0 1 Active high, level sensitive 0 1 Active high, level sensitive INT0 and INT1 are assigned to Port pins as defined in the IT01CF register (see SFR Definition 14.7). Note that INT0 and INT0 Port pin assignments are independent of any Crossbar assignments. INT0 and INT1 will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin via the Crossbar. To assign a Port pin only to INT0 and/or INT1, configure the Crossbar to skip the selected pin(s). This is accomplished by setting the associated bit in register XBR0 (see Section “20.3. Priority Crossbar Decoder” on page 180 for complete details on configuring the Crossbar). 126 Rev. 1.2

C8051F50x/F51x IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flags for the INT0 and INT1 external inter- rupts, respectively. If an INT0 or INT1 external interrupt is configured as edge-sensitive, the corresponding interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When configured as level sensitive, the interrupt-pending flag remains logic 1 while the input is active as defined by the corresponding polarity bit (IN0PL or IN1PL); the flag remains logic 0 while the input is inactive. The external interrupt source must hold the input active until the interrupt request is recognized. It must then deactivate the interrupt request before execution of the ISR completes or another interrupt request will be generated. Rev. 1.2 127

C8051F50x/F51x SFR Definition 14.7. IT01CF: INT0/INT1 Configuration Bit 7 6 5 4 3 2 1 0 Name IN1PL IN1SL[2:0] IN0PL IN0SL[2:0] Type R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xE4; SFR Page = 0x0F Bit Name Function 7 IN1PL INT1 Polarity. 0: INT1 input is active low. 1: INT1 input is active high. 6:4 IN1SL[2:0] INT1 Port Pin Selection Bits. These bits select which Port pin is assigned to INT1. Note that this pin assignment is independent of the Crossbar; INT1 will monitor the assigned Port pin without disturb- ing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not assign the Port pin to a peripheral if it is configured to skip the selected pin. 000: Select P1.0 001: Select P1.1 010: Select P1.2 011: Select P1.3 100: Select P1.4 101: Select P1.5 110: Select P1.6 111: Select P1.7 3 IN0PL INT0 Polarity. 0: INT0 input is active low. 1: INT0 input is active high. 2:0 IN0SL[2:0] INT0 Port Pin Selection Bits. These bits select which Port pin is assigned to INT0. Note that this pin assignment is independent of the Crossbar; INT0 will monitor the assigned Port pin without disturb- ing the peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not assign the Port pin to a peripheral if it is configured to skip the selected pin. 000: Select P1.0 001: Select P1.1 010: Select P1.2 011: Select P1.3 100: Select P1.4 101: Select P1.5 110: Select P1.6 111: Select P1.7 128 Rev. 1.2

C8051F50x/F51x 15. Flash Memory On-chip, re-programmable Flash memory is included for program code and non-volatile data storage. The Flash memory can be programmed in-system, a single byte at a time, through the C2 interface or by soft- ware using the MOVX instruction. Once cleared to logic 0, a Flash bit must be erased to set it back to logic 1. Flash bytes would typically be erased (set to 0xFF) before being reprogrammed. The write and erase operations are automatically timed by hardware for proper execution; data polling to determine the end of the write/erase operation is not required. Code execution is stalled during a Flash write/erase oper- ation. Refer to Table 5.5 for complete Flash memory electrical characteristics. 15.1. Programming the Flash Memory The simplest means of programming the Flash memory is through the C2 interface using programming tools provided by Silicon Labs or a third party vendor. This is the only means for programming a non-initial- ized device. For details on the C2 commands to program Flash memory, see Section “28. C2 Interface” on page 306. To ensure the integrity of Flash contents, The on-chip V Monitor must be enabled in any system that DD includes code that writes and/or erases Flash memory from software. See Section 15.4 for more details. Before performing any Flash write or erase procedure, set the FLEWT bit in Flash Scale register (FLSCL) to ‘1’. Also, note that 8-bit MOVX instructions cannot be used to erase or write to Flash memory at addresses higher than 0x00FF. 15.1.1. Flash Lock and Key Functions Flash writes and erases by user software are protected with a lock and key function. The Flash Lock and Key Register (FLKEY) must be written with the correct key codes, in sequence, before Flash operations may be performed. The key codes are: 0xA5, 0xF1. The timing does not matter, but the codes must be written in order. If the key codes are written out of order, or the wrong codes are written, Flash writes and erases will be disabled until the next system reset. Flash writes and erases will also be disabled if a Flash write or erase is attempted before the key codes have been written properly. The Flash lock resets after each write or erase; the key codes must be written again before a following Flash operation can be per- formed. The FLKEY register is detailed in SFR Definition 15.2. 15.1.2. Flash Erase Procedure The Flash memory can be programmed by software using the MOVX write instruction with the address and data byte to be programmed provided as normal operands. Before writing to Flash memory using MOVX, Flash write operations must be enabled by doing the following: (1) setting the PSWE Program Store Write Enable bit (PSCTL.0) to logic 1 (this directs the MOVX writes to target Flash memory); and (2) Writing the Flash key codes in sequence to the Flash Lock register (FLKEY). The PSWE bit remains set until cleared by software. A write to Flash memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits to logic 1 in Flash. A byte location to be programmed should be erased before a new value is written. The Flash memory is organized in 512-byte pages. The erase operation applies to an entire page (setting all bytes in the page to 0xFF). To erase an entire 512-byte page, perform the following steps: 1. Disable interrupts (recommended). 2. Set the PSEE bit (register PSCTL). 3. Set the PSWE bit (register PSCTL). 4. Write the first key code to FLKEY: 0xA5. 5. Write the second key code to FLKEY: 0xF1. 6. Using the MOVX instruction, write a data byte to any location within the 512-byte page to be erased. 7. Clear the PSWE and PSEE bits. Rev. 1.2 129

C8051F50x/F51x 15.1.3. Flash Write Procedure Flash bytes are programmed by software with the following sequence: 1. Disable interrupts (recommended). 2. Erase the 512-byte Flash page containing the target location, as described in Section 15.1.2. 3. Set the PSWE bit (register PSCTL). 4. Clear the PSEE bit (register PSCTL). 5. Write the first key code to FLKEY: 0xA5. 6. Write the second key code to FLKEY: 0xF1. 7. Using the MOVX instruction, write a single data byte to the desired location within the 512-byte sector. 8. Clear the PSWE bit. Steps 5–7 must be repeated for each byte to be written. After Flash writes are complete, PSWE should be cleared so that MOVX instructions do not target program memory. 15.1.4. Flash Write Optimization The Flash write procedure includes a block write option to optimize the time to perform consecutive byte writes. When block write is enabled by setting the CHBLKW bit (CCH0CN.0), writes to two consecutive bytes in Flash require the same amount of time as a single byte write. This is performed by caching the first byte that is written to Flash and then committing both bytes to Flash when the second byte is written. When block writes are enabled, if the second write does not occur, the first data byte written is not actually written to Flash. Flash bytes with block write enabled are programmed by software with the following sequence: 1. Disable interrupts (recommended). 2. Erase the 512-byte Flash page containing the target location, as described in Section 15.1.2. 3. Set the CHBLKW bit (register CCH0CN). 4. Set the PSWE bit (register PSCTL). 5. Clear the PSEE bit (register PSCTL). 6. Write the first key code to FLKEY: 0xA5. 7. Write the second key code to FLKEY: 0xF1. 8. Using the MOVX instruction, write the first data byte to the desired location within the 512-byte sector. 9. Write the first key code to FLKEY: 0xA5. 10.Write the second key code to FLKEY: 0xF1. 11.Using the MOVX instruction, write the second data byte to the desired location within the 512-byte sector. The location of the second byte must be the next higher address from the first data byte. 12.Clear the PSWE bit. 13.Clear the CHBLKW bit. 130 Rev. 1.2

C8051F50x/F51x 15.2. Non-volatile Data Storage The Flash memory can be used for non-volatile data storage as well as program code. This allows data such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX write instruction and read using the MOVC instruction. Note: MOVX read instructions always target XRAM. 15.3. Security Options The CIP-51 provides security options to protect the Flash memory from inadvertent modification by soft- ware as well as to prevent the viewing of proprietary program code and constants. The Program Store Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register PSCTL) bits protect the Flash memory from accidental modification by software. PSWE must be explicitly set to 1 before software can modify the Flash memory; both PSWE and PSEE must be set to 1 before soft- ware can erase Flash memory. Additional security features prevent proprietary program code and data constants from being read or altered across the C2 interface. A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program memory from access (reads, writes, or erases) by unprotected code or the C2 interface. The Flash security mechanism allows the user to lock n 512-byte Flash pages, starting at page 0 (addresses 0x0000 to 0x01FF), where n is the ones complement number represented by the Security Lock Byte. Note that the page containing the Flash Security Lock Byte is unlocked when no other Flash pages are locked (all bits of the Lock Byte are 1) and locked when any other Flash pages are locked (any bit of the Lock Byte is 0). See example in Figure 15.1. Reserved Area Lock Byte Locked when any other FLASH Lock Byte Page pages are locked Unlocked FLASH Pages Access limit set according to the FLASH security lock byte Locked Flash Pages Security Lock Byte: 11111101b 1s Complement: 00000010b Flash pages locked: 3 (First two Flash pages + Lock Byte Page) Figure 15.1. Flash Program Memory Map Rev. 1.2 131

C8051F50x/F51x The level of Flash security depends on the Flash access method. The three Flash access methods that can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing on unlocked pages, and user firmware executing on locked pages. Table 15.1 summarizes the Flash security features of the C8051F50x/F51x devices. Table 15.1. Flash Security Summary Action C2 Debug User Firmware executing from: Interface an unlocked page a locked page Read, Write or Erase unlocked pages Permitted Permitted Permitted (except page with Lock Byte) Read, Write or Erase locked pages Not Permitted Flash Error Reset Permitted (except page with Lock Byte) Read or Write page containing Lock Byte Permitted Permitted Permitted (if no pages are locked) Read or Write page containing Lock Byte Not Permitted Flash Error Reset Permitted (if any page is locked) Read contents of Lock Byte Permitted Permitted Permitted (if no pages are locked) Read contents of Lock Byte Not Permitted Flash Error Reset Permitted (if any page is locked) Erase page containing Lock Byte Permitted Flash Error Reset Flash Error Reset (if no pages are locked) Erase page containing Lock Byte—Unlock all C2 Device Flash Error Reset Flash Error Reset pages (if any page is locked) Erase Only Lock additional pages Not Permitted Flash Error Reset Flash Error Reset (change 1s to 0s in the Lock Byte) Unlock individual pages Not Permitted Flash Error Reset Flash Error Reset (change 0s to 1s in the Lock Byte) Read, Write or Erase Reserved Area Not Permitted Flash Error Reset Flash Error Reset C2 Device Erase—Erases all Flash pages including the page containing the Lock Byte. Flash Error Reset—Not permitted; Causes Flash Error Device Reset (FERROR bit in RSTSRC is '1' after reset). - All prohibited operations that are performed via the C2 interface are ignored (do not cause device reset). - Locking any Flash page also locks the page containing the Lock Byte. - Once written to, the Lock Byte cannot be modified except by performing a C2 Device Erase. - If user code writes to the Lock Byte, the Lock does not take effect until the next device reset. 132 Rev. 1.2

C8051F50x/F51x 15.4. Flash Write and Erase Guidelines Any system which contains routines which write or erase Flash memory from software involves some risk that the write or erase routines will execute unintentionally if the CPU is operating outside its specified operating range of V , system clock frequency, or temperature. This accidental execution of Flash modi- DD fying code can result in alteration of Flash memory contents causing a system failure that is only recover- able by re-Flashing the code in the device. The following guidelines are recommended for any system which contains routines which write or erase Flash from code. 15.4.1. V Maintenance and the V monitor DD DD 1. If the system power supply is subject to voltage or current "spikes," add sufficient transient protection devices to the power supply to ensure that the supply voltages listed in the Absolute Maximum Ratings table are not exceeded. 2. The on-chip V monitor is turned on and enabled as a reset source by default by the hardware. If it is DD disabled by the firmware, use the following recommendations when re-enabling the V monitor. Turn DD on the V monitor and enable it as a reset source as early in code as possible. This should be the first DD set of instructions executed after the Reset Vector. For C-based systems, this will involve modifying the startup code added by the C compiler. See your compiler documentation for more details. Make certain that there are no delays in software between enabling the V monitor and enabling the V monitor as DD DD a reset source. Code examples showing this can be found in “AN201: Writing to Flash from Firmware", available from the Silicon Laboratories web site. 3. As an added precaution, explicitly enable the V monitor and enable the V monitor as a reset DD DD source inside the functions that write and erase Flash memory. The V monitor enable instructions DD should be placed just after the instruction to set PSWE to a 1, but before the Flash write or erase operation instruction. 4. Make certain that all writes to the RSTSRC (Reset Sources) register use direct assignment operators and explicitly DO NOT use the bit-wise operators (such as AND or OR). For example, "RSTSRC = 0x02" is correct. "RSTSRC |= 0x02" is incorrect. 5. Make certain that all writes to the RSTSRC register explicitly set the PORSF bit to a 1. Areas to check are initialization code which enables other reset sources, such as the Missing Clock Detector or Comparator, for example, and instructions which force a Software Reset. A global search on "RSTSRC" can quickly verify this. 15.4.2. PSWE Maintenance 1. Reduce the number of places in code where the PSWE bit (b0 in PSCTL) is set to a 1. There should be exactly one routine in code that sets PSWE to a 1 to write Flash bytes and one routine in code that sets PSWE and PSEE both to a 1 to erase Flash pages. 2. Minimize the number of variable accesses while PSWE is set to a 1. Handle pointer address updates and loop variable maintenance outside the "PSWE = 1;... PSWE = 0;" area. Code examples showing this can be found in ”AN201: Writing to Flash from Firmware" available from the Silicon Laboratories web site. 3. Disable interrupts prior to setting PSWE to a 1 and leave them disabled until after PSWE has been reset to '0'. Any interrupts posted during the Flash write or erase operation will be serviced in priority order after the Flash operation has been completed and interrupts have been re-enabled by software. 4. Make certain that the Flash write and erase pointer variables are not located in XRAM. See your compiler documentation for instructions regarding how to explicitly locate variables in different memory areas. 5. Add address bounds checking to the routines that write or erase Flash memory to ensure that a routine called with an illegal address does not result in modification of the Flash. Rev. 1.2 133

C8051F50x/F51x 15.4.3. System Clock 1. If operating from an external crystal, be advised that crystal performance is susceptible to electrical interference and is sensitive to layout and to changes in temperature. If the system is operating in an electrically noisy environment, use the internal oscillator or use an external CMOS clock. 2. If operating from the external oscillator, switch to the internal oscillator during Flash write or erase operations. The external oscillator can continue to run, and the CPU can switch back to the external oscillator after the Flash operation has completed. Additional Flash recommendations and example code can be found in ”AN201: Writing to Flash from Firm- ware" available from the Silicon Laboratories web site. SFR Definition 15.1. PSCTL: Program Store R/W Control Bit 7 6 5 4 3 2 1 0 Name PSEE PSWE Type R R R R R R R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x8F; SFR Page = 0x00 Bit Name Function 7:2 Unused Read = 000000b, Write = don’t care. 1 PSEE Program Store Erase Enable. Setting this bit (in combination with PSWE) allows an entire page of Flash program memory to be erased. If this bit is logic 1 and Flash writes are enabled (PSWE is logic 1), a write to Flash memory using the MOVX instruction will erase the entire page that contains the location addressed by the MOVX instruction. The value of the data byte written does not matter. 0: Flash program memory erasure disabled. 1: Flash program memory erasure enabled. 0 PSWE Program Store Write Enable. Setting this bit allows writing a byte of data to the Flash program memory using the MOVX write instruction. The Flash location should be erased before writing data. 0: Writes to Flash program memory disabled. 1: Writes to Flash program memory enabled; the MOVX write instruction targets Flash memory. 134 Rev. 1.2

C8051F50x/F51x SFR Definition 15.2. FLKEY: Flash Lock and Key Bit 7 6 5 4 3 2 1 0 Name FLKEY[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xB7; SFR Page = All Pages Bit Name Function 7:0 FLKEY[7:0] Flash Lock and Key Register. Write: This register provides a lock and key function for Flash erasures and writes. Flash writes and erases are enabled by writing 0xA5 followed by 0xF1 to the FLKEY regis- ter. Flash writes and erases are automatically disabled after the next write or erase is complete. If any writes to FLKEY are performed incorrectly, or if a Flash write or erase operation is attempted while these operations are disabled, the Flash will be perma- nently locked from writes or erasures until the next device reset. If an application never writes to Flash, it can intentionally lock the Flash by writing a non-0xA5 value to FLKEY from software. Read: When read, bits 1–0 indicate the current Flash lock state. 00: Flash is write/erase locked. 01: The first key code has been written (0xA5). 10: Flash is unlocked (writes/erases allowed). 11: Flash writes/erases disabled until the next reset. Rev. 1.2 135

C8051F50x/F51x SFR Definition 15.3. FLSCL: Flash Scale Bit 7 6 5 4 3 2 1 0 Name Reserved Reserved Reserved FLRT Reserved Reserved FLEWT Reserved Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xB6; SFR Page = All Pages Bit Name Function 7:5 Reserved Must Write 000b. 4 FLRT Flash Read Time Control. This bit should be programmed to the smallest allowed value, according to the system clock speed. 0: SYSCLK < 25 MHz (Flash read strobe is one system clock). 1: SYSCLK > 25 MHz (Flash read strobe is two system clocks). 3:2 Reserved Must Write 00b. 1 FLEWT Flash Erase Write Time Control. This bit should be set to 1b before Writing or Erasing Flash. 0: Short Flash Erase / Write Timing. 1: Extended Flash Erase / Write Timing. 0 Reserved Must Write 0b. 136 Rev. 1.2

C8051F50x/F51x SFR Definition 15.4. CCH0CN: Cache Control Bit 7 6 5 4 3 2 1 0 Name Reserved Reserved CHPFEN Reserved Reserved Reserved Reserved CHBLKW Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 1 0 0 0 0 0 SFR Address = 0xE3; SFR Page = 0x0F Bit Name Function 7:6 Reserved Must Write 00b 5 CHPFEN Cache Prefect Enable Bit. 0: Prefetch engine is disabled. 1: Prefetch engine is enabled. 4:1 Reserved Must Write 0000b. 0 CHBLKW Block Write Enable Bit. This bit allows block writes to Flash memory from firmware. 0: Each byte of a software Flash write is written individually. 1: Flash bytes are written in groups of two. SFR Definition 15.5. ONESHOT: Flash Oneshot Period Bit 7 6 5 4 3 2 1 0 Name PERIOD[3:0] Type R R R R R/W R/W R/W R/W Reset 0 0 0 0 1 1 1 1 SFR Address = 0xBE; SFR Page = 0x0F Bit Name Function 7:4 Unused Read = 0000b. Write = don’t care. 3:0 PERIOD[3:0] Oneshot Period Control Bits. These bits limit the internal Flash read strobe width as follows. When the Flash read strobe is de-asserted, the Flash memory enters a low-power state for the remainder of the system clock cycle. These bits have no effect when the system clocks is greater than 12.5 MHz and FLRT = 0. FLASH = 5ns+(PERIOD×5ns) RDMAX Rev. 1.2 137

C8051F50x/F51x 16. Power Management Modes The C8051F50x/F51x devices have three software programmable power management modes: Idle, Stop, and Suspend. Idle mode and Stop mode are part of the standard 8051 architecture, while Suspend mode is an enhanced power-saving mode implemented by the high-speed oscillator peripheral. Idle mode halts the CPU while leaving the peripherals and clocks active. In Stop mode, the CPU is halted, all interrupts and timers (except the Missing Clock Detector) are inactive, and the internal oscillator is stopped (analog peripherals remain in their selected states; the external oscillator is not affected). Sus- pend mode is similar to Stop mode in that the internal oscillator and CPU are halted, but the device can wake on events such as a Port Match or Comparator low output. Since clocks are running in Idle mode, power consumption is dependent upon the system clock frequency and the number of peripherals left in active mode before entering Idle. Stop mode and Suspend mode consume the least power because the majority of the device is shut down with no clocks active. SFR Definition 16.1 describes the Power Control Register (PCON) used to control the C8051F50x/F51x devices’ Stop and Idle power management modes. Suspend mode is controlled by the SUSPEND bit in the OSCICN register (SFR Definition 19.2). Although the C8051F50x/F51x has Idle, Stop, and Suspend modes available, more control over the device power can be achieved by enabling/disabling individual peripherals as needed. Each analog peripheral can be disabled when not in use and placed in low power mode. Digital peripherals, such as timers or serial buses, draw little power when they are not in use. Turning off oscillators lowers power consumption considerably, at the expense of reduced functionality. 16.1. Idle Mode Setting the Idle Mode Select bit (PCON.0) causes the hardware to halt the CPU and enter Idle mode as soon as the instruction that sets the bit completes execution. All internal registers and memory maintain their original data. All analog and digital peripherals can remain active during Idle mode. Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume operation. The pending interrupt will be serviced and the next instruction to be executed after the return from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit. If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence and begins program execution at address 0x0000. Note: If the instruction following the write of the IDLE bit is a single-byte instruction and an interrupt occurs during the execution phase of the instruction that sets the IDLE bit, the CPU may not wake from Idle mode when a future interrupt occurs. Therefore, instructions that set the IDLE bit should be followed by an instruction that has two or more opcode bytes, for example: // in ‘C’: PCON |= 0x01; // set IDLE bit PCON = PCON; // ... followed by a 3-cycle dummy instruction ; in assembly: ORL PCON, #01h ; set IDLE bit MOV PCON, PCON ; ... followed by a 3-cycle dummy instruction If enabled, the Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby termi- nate the Idle mode. This feature protects the system from an unintended permanent shutdown in the event of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by software prior to entering the Idle mode if the WDT was initially configured to allow this operation. This pro- vides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefi- nitely, waiting for an external stimulus to wake up the system. Refer to Section “17.6. PCA Watchdog Timer Reset” on page 145 for more information on the use and configuration of the WDT. Rev. 1.2 138

C8051F50x/F51x 16.2. Stop Mode Setting the Stop Mode Select bit (PCON.1) causes the controller core to enter Stop mode as soon as the instruction that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital peripherals are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral (including the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop mode can only be terminated by an internal or external reset. On reset, the device performs the normal reset sequence and begins program execution at address 0x0000. If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode. The Missing Clock Detector should be disabled if the CPU is to be put to in STOP mode for longer than the MCD timeout of 100 µs. 16.3. Suspend Mode Setting the SUSPEND bit (OSCICN.5) causes the hardware to halt the CPU and the high-frequency inter- nal oscillator, and go into Suspend mode as soon as the instruction that sets the bit completes execution. All internal registers and memory maintain their original data. Most digital peripherals are not active in Sus- pend mode. The exception to this is the Port Match feature. Suspend mode can be terminated by three types of events, a port match (described in Section “20.5. Port Match” on page 187), a Comparator low output (if enabled), or a device reset event. When Suspend mode is terminated, the device will continue execution on the instruction following the one that set the SUSPEND bit. If the wake event was configured to generate an interrupt, the interrupt will be serviced upon waking the device. If Suspend mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence and begins program execution at address 0x0000. Note: When entering suspend mode, firmware must set the ZTCEN bit in REF0CN (SFR Definition 8.1). 139 Rev. 1.2

C8051F50x/F51x SFR Definition 16.1. PCON: Power Control Bit 7 6 5 4 3 2 1 0 Name GF[5:0] STOP IDLE Type R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x87; SFR Page = All Pages Bit Name Function 7:2 GF[5:0] General Purpose Flags 5–0. These are general purpose flags for use under software control. 1 STOP Stop Mode Select. Setting this bit will place the CIP-51 in Stop mode. This bit will always be read as 0. 1: CPU goes into Stop mode (internal oscillator stopped). 0 IDLE IDLE: Idle Mode Select. Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0. 1: CPU goes into Idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts, Serial Ports, and Analog Peripherals are still active.) Rev. 1.2 140

C8051F50x/F51x 17. Reset Sources Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this reset state, the following occur:  CIP-51 halts program execution  Special Function Registers (SFRs) are initialized to their defined reset values  External Port pins are forced to a known state  Interrupts and timers are disabled. All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal data memory are unaffected during a reset; any previously stored data is preserved. However, since the stack pointer SFR is reset, the stack is effectively lost, even though the data on the stack is not altered. The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pullups are enabled during and after the reset. For V Monitor and power-on resets, the RST pin is driven low until the device DD exits the reset state. On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the inter- nal oscillator. The Watchdog Timer is enabled with the system clock divided by 12 as its clock source. Pro- gram execution begins at location 0x0000. VDD Power On Reset Supply Monitor + '0' /RST Px.x Comparator 0 - Enable (wired-OR) + - Px.x C0RSEF Missing Reset Clock Detector Funnel (one- shot) PCA WDT (Software Reset) EN SWRSF EN Errant MCDnable WDTnable OFpLeAraStiHon E E System Clock CIP-51 Microcontroller System Reset Core Extended Interrupt Handler Figure 17.1. Reset Sources Rev. 1.2 141

C8051F50x/F51x 17.1. Power-On Reset During power-up, the device is held in a reset state and the RST pin is driven low until V settles above DD V . A delay occurs before the device is released from reset; the delay decreases as the V ramp time RST DD increases (V ramp time is defined as how fast V ramps from 0 V to V ). Figure 17.2. plots the DD DD RST power-on and V monitor reset timing. DD On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. When PORSF is set, all of the other reset flags in the RSTSRC Register are indeterminate (PORSF is cleared by all other resets). Since all resets cause program execution to begin at the same location (0x0000) software can read the PORSF flag to determine if a power-up was the cause of reset. The content of internal data mem- ory should be assumed to be undefined after a power-on reset. The V monitor is enabled following a DD power-on reset. s olt VDD v 2.45 V RST 2.25 2.0 D D V 1.0 t /RST Logic HIGH T PORDelay Logic LOW VDD Power-On Monitor Reset Reset Figure 17.2. Power-On and V Monitor Reset Timing DD 17.2. Power-Fail Reset/V Monitor DD When a power-down transition or power irregularity causes V to drop below V , the power supply DD RST monitor will drive the RST pin low and hold the CIP-51 in a reset state (see Figure 17.2). When V returns DD to a level above V , the CIP-51 will be released from the reset state. Note that even though internal data RST memory contents are not altered by the power-fail reset, it is impossible to determine if V dropped below DD the level required for data retention. If the PORSF flag reads 1, the data may no longer be valid. The V DD monitor is enabled after power-on resets. Its defined state (enabled/disabled) is not altered by any other reset source. For example, if the V monitor is disabled by code and a software reset is performed, the DD V monitor will still be disabled after the reset. To protect the integrity of Flash contents, the V DD DD monitor must be enabled to the higher setting (VDMLVL = 1) and selected as a reset source if soft- ware contains routines which erase or write Flash memory. If the V monitor is not enabled and DD set to the high level, any erase or write performed on Flash memory will cause a Flash Error device reset. 142 Rev. 1.2

C8051F50x/F51x Important Note: If the V monitor is being turned on from a disabled state, it should be enabled before it DD is selected as a reset source. Selecting the V monitor as a reset source before it is enabled and stabi- DD lized may cause a system reset. In some applications, this reset may be undesirable. If this is not desirable in the application, a delay should be introduced between enabling the monitor and selecting it as a reset source. The procedure for enabling the V monitor and configuring it as a reset source from a disabled DD state is as follows: 1. Enable the V monitor (VDMEN bit in VDM0CN = 1). DD 2. If necessary, wait for the V monitor to stabilize (see Table 5.4 for the V Monitor turn-on time). DD DD Note: This delay should be omitted if software contains routines that erase or write Flash memory. 3. Select the V monitor as a reset source (PORSF bit in RSTSRC = 1). DD See Figure 17.2 for V monitor timing; note that the power-on-reset delay is not incurred after a V DD DD monitor reset. See Table 5.4 for complete electrical characteristics of the V monitor. DD See “Figure 5.1. Minimum VDD Monitor Threshold vs. System Clock Frequency” on page 44 for V mon- DD itor threshold level requirements. Note: The output of the internal voltage regulator is calibrated by the MCU immediately after any reset event. The output of the un-calibrated internal regulator could be below the high threshold setting of the VDD Monitor. If this is the case and the VDD Monitor is set to the high threshold setting and if the MCU receives a non-power on reset (POR), the MCU will remain in reset until a POR occurs (i.e., VDD Monitor will keep the device in reset). A POR will force the VDD Monitor to the low threshold setting which is guaranteed to be below the un- calibrated output of the internal regulator. The device will then exit reset and resume normal operation. It is for this reason Silicon Labs strongly recommends that the VDD Monitor is always left in the low threshold setting (i.e., default value upon POR). When programming the Flash in-system, the VDD Monitor must be set to the high threshold setting. For the highest system reliability, the time the VDD Monitor is set to the high threshold setting should be minimized (e.g. setting the VDD Monitor to the high threshold setting just before the Flash write operation and then changing it back to the low threshold setting immediately after the Flash write operation). Rev. 1.2 143

C8051F50x/F51x SFR Definition 17.1. VDM0CN: V Monitor Control DD Bit 7 6 5 4 3 2 1 0 Name VDMEN VDDSTAT VDMLVL Type R/W R R/W R R R R R Reset Varies Varies 0 0 0 0 0 0 SFR Address = 0xFF; SFR Page = 0x00 Bit Name Function 7 VDMEN V Monitor Enable. DD This bit turns the V monitor circuit on/off. The V Monitor cannot generate sys- DD DD tem resets until it is also selected as a reset source in register RSTSRC (SFR Defi- nition 17.2). Selecting the V monitor as a reset source before it has stabilized DD may generate a system reset. In systems where this reset would be undesirable, a delay should be introduced between enabling the V Monitor and selecting it as a DD reset source. See Table 5.4 for the minimum V Monitor turn-on time. DD 0: V Monitor Disabled. DD 1: V Monitor Enabled. DD 6 VDDSTAT V Status. DD This bit indicates the current power supply status (V Monitor output). DD 0: V is at or below the V monitor threshold. DD DD 1: V is above the V monitor threshold. DD DD 5 VDMLVL V Monitor Level Select. DD 0: V Monitor Threshold is set to VRST-LOW DD 1: V Monitor Threshold is set to VRST-HIGH. This setting is required for any sys- DD tem includes code that writes to and/or erases Flash. 4:0 Unused Read = 00000b; Write = Don’t care. 17.3. External Reset The external RST pin provides a means for external circuitry to force the device into a reset state. Assert- ing an active-low signal on the RST pin generates a reset; an external pullup and/or decoupling of the RST pin may be necessary to avoid erroneous noise-induced resets. See Table 5.4 for complete RST pin spec- ifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset. 17.4. Missing Clock Detector Reset The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the system clock. If the system clock remains high or low for more than the value specified in Table 5.4, “Reset Electrical Characteristics,” on page 46, the one-shot will time out and generate a reset. After a MCD reset, the MCDRSF flag (RSTSRC.2) will read 1, signifying the MCD as the reset source; otherwise, this bit reads 0. Writing a 1 to the MCDRSF bit enables the Missing Clock Detector; writing a 0 disables it. The state of the RST pin is unaffected by this reset. 144 Rev. 1.2

C8051F50x/F51x 17.5. Comparator0 Reset Comparator0 can be configured as a reset source by writing a 1 to the C0RSEF flag (RSTSRC.5). Com- parator0 should be enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on chatter on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the non-inverting input voltage (on CP0+) is less than the inverting input voltage (on CP0–), the device is put into the reset state. After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read 1 signifying Comparator0 as the reset source; otherwise, this bit reads 0. The state of the RST pin is unaffected by this reset. 17.6. PCA Watchdog Timer Reset The programmable Watchdog Timer (WDT) function of the Programmable Counter Array (PCA) can be used to prevent software from running out of control during a system malfunction. The PCA WDT function can be enabled or disabled by software as described in Section “27.4. Watchdog Timer Mode” on page 297; the WDT is enabled and clocked by SYSCLK/12 following any reset. If a system malfunction prevents user software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is set to 1. The state of the RST pin is unaffected by this reset. 17.7. Flash Error Reset If a Flash read/write/erase or program read targets an illegal address, a system reset is generated. This may occur due to any of the following:  A Flash write or erase is attempted above user code space. This occurs when PSWE is set to 1 and a MOVX write operation targets an address in or above the reserved space.  A Flash read is attempted above user code space. This occurs when a MOVC operation targets an address in or above the reserved space.  A Program read is attempted above user code space. This occurs when user code attempts to branch to an address in or above the reserved space.  A Flash read, write or erase attempt is restricted due to a Flash security setting (see Section “15.3. Security Options” on page 131).  A Flash read, write, or erase is attempted when the VDD Monitor is not enabled to the high threshold and set as a reset source. The FERROR bit (RSTSRC.6) is set following a Flash error reset. The state of the RST pin is unaffected by this reset. 17.8. Software Reset Software may force a reset by writing a 1 to the SWRSF bit (RSTSRC.4). The SWRSF bit will read 1 fol- lowing a software forced reset. The state of the RST pin is unaffected by this reset. Rev. 1.2 145

C8051F50x/F51x SFR Definition 17.2. RSTSRC: Reset Source Bit 7 6 5 4 3 2 1 0 Name FERROR C0RSEF SWRSF WDTRSF MCDRSF PORSF PINRSF Type R R R/W R/W R R/W R/W R Reset 0 Varies Varies Varies Varies Varies Varies Varies SFR Address = 0xEF; SFR Page = 0x00 Bit Name Description Write Read 7 Unused Unused. Don’t care. 0 6 FERROR Flash Error Reset Flag. N/A Set to 1 if Flash read/write/erase error caused the last reset. 5 C0RSEF Comparator0 Reset Enable Writing a 1 enables Set to 1 if Comparator0 and Flag. Comparator0 as a reset caused the last reset. source (active-low). 4 SWRSF Software Reset Force and Writing a 1 forces a sys- Set to 1 if last reset was Flag. tem reset. caused by a write to SWRSF. 3 WDTRSF Watchdog Timer Reset Flag. N/A Set to 1 if Watchdog Timer overflow caused the last reset. 2 MCDRSF Missing Clock Detector Writing a 1 enables the Set to 1 if Missing Clock Enable and Flag. Missing Clock Detector. Detector timeout caused The MCD triggers a reset the last reset. if a missing clock condition is detected. 1 PORSF Power-On/V Monitor Writing a 1 enables the Set to 1 anytime a power- DD Reset Flag, and VDD monitor VDD monitor as a reset on or VDD monitor reset source. occurs. Reset Enable. Writing 1 to this bit When set to 1 all other before the V monitor RSTSRC flags are inde- DD is enabled and stabilized terminate. may cause a system reset. 0 PINRSF HW Pin Reset Flag. N/A Set to 1 if RST pin caused the last reset. Note: Do not use read-modify-write operations on this register 146 Rev. 1.2

C8051F50x/F51x 18. External Data Memory Interface and On-Chip XRAM For C8051F50x/F51x devices, 4 kB of RAM are included on-chip and mapped into the external data mem- ory space (XRAM). Additionally, an External Memory Interface (EMIF) is available on the C8051F500/1/4/5 and C8051F508/9-F510/1 devices, which can be used to access off-chip data memories and memory- mapped devices connected to the GPIO ports. The external memory space may be accessed using the external move instruction (MOVX) and the data pointer (DPTR), or using the MOVX indirect addressing mode using R0 or R1. If the MOVX instruction is used with an 8-bit address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN, shown in SFR Definition 18.1). Note: The MOVX instruction can also be used for writing to the Flash memory. See Section “15. Flash Memory” on page 129 for details. The MOVX instruction accesses XRAM by default. 18.1. Accessing XRAM The XRAM memory space is accessed using the MOVX instruction. The MOVX instruction has two forms, both of which use an indirect addressing method. The first method uses the Data Pointer, DPTR, a 16-bit register which contains the effective address of the XRAM location to be read from or written to. The sec- ond method uses R0 or R1 in combination with the EMI0CN register to generate the effective XRAM address. Examples of both of these methods are given below. 18.1.1. 16-Bit MOVX Example The 16-bit form of the MOVX instruction accesses the memory location pointed to by the contents of the DPTR register. The following series of instructions reads the value of the byte at address 0x1234 into the accumulator A: MOV DPTR, #1234h ; load DPTR with 16-bit address to read (0x1234) MOVX A, @DPTR ; load contents of 0x1234 into accumulator A The above example uses the 16-bit immediate MOV instruction to set the contents of DPTR. Alternately, the DPTR can be accessed through the SFR registers DPH, which contains the upper 8-bits of DPTR, and DPL, which contains the lower 8-bits of DPTR. 18.1.2. 8-Bit MOVX Example The 8-bit form of the MOVX instruction uses the contents of the EMI0CN SFR to determine the upper 8-bits of the effective address to be accessed and the contents of R0 or R1 to determine the lower 8-bits of the effective address to be accessed. The following series of instructions read the contents of the byte at address 0x1234 into the accumulator A. MOV EMI0CN, #12h ; load high byte of address into EMI0CN MOV R0, #34h ; load low byte of address into R0 (or R1) MOVX a, @R0 ; load contents of 0x1234 into accumulator A Rev. 1.2 147

C8051F50x/F51x 18.2. Configuring the External Memory Interface Configuring the External Memory Interface consists of five steps: 1. Configure the Output Modes of the associated port pins as either push-pull or open-drain (push-pull is most common), and skip the associated pins in the crossbar. 2. Configure Port latches to “park” the EMIF pins in a dormant state (usually by setting them to logic 1). 3. Select Multiplexed mode or Non-multiplexed mode. 4. Select the memory mode (on-chip only, split mode without bank select, split mode with bank select, or off-chip only). 5. Set up timing to interface with off-chip memory or peripherals. Each of these five steps is explained in detail in the following sections. The Port selection, Multiplexed mode selection, and Mode bits are located in the EMI0CF register shown in SFR Definition . 18.3. Port Configuration The External Memory Interface appears on Ports 1, 2, 3, and 4 when it is used for off-chip memory access. When the EMIF is used, the Crossbar should be configured to skip over the /RD control line (P1.6) and the /WR control line (P1.7) using the P1SKIP register. When the EMIF is used in multiplexed mode, the Cross- bar should also skip over the ALE control line (P1.5). For more information about configuring the Crossbar, see Section “20.6. Special Function Registers for Accessing and Configuring Port I/O” on page 191. The EMIF pinout is shown in Table 18.1 on page 149. The External Memory Interface claims the associated Port pins for memory operations ONLY during the execution of an off-chip MOVX instruction. Once the MOVX instruction has completed, control of the Port pins reverts to the Port latches or to the Crossbar settings for those pins. See Section “20. Port Input/Out- put” on page 177 for more information about the Crossbar and Port operation and configuration. The Port latches should be explicitly configured to “park” the External Memory Interface pins in a dormant state, most commonly by setting them to a logic 1. During the execution of the MOVX instruction, the External Memory Interface will explicitly disable the driv- ers on all Port pins that are acting as Inputs (Data[7:0] during a READ operation, for example). The Output mode of the Port pins (whether the pin is configured as Open-Drain or Push-Pull) is unaffected by the External Memory Interface operation, and remains controlled by the PnMDOUT registers. In most cases, the output modes of all EMIF pins should be configured for push-pull mode. The C8051F500/1/4/5 devices support both the multiplexed and non-multiplexed modes and the C8051F508/9-F510/1 devices support only multiplexed modes. Accessing off-chip memory is not sup- ported by the C8051F502/3/6/7 devices. 148 Rev. 1.2

C8051F50x/F51x Table 18.1. EMIF Pinout (C8051F500/1/4/5) Multiplexed Mode Non Multiplexed Mode Signal Name Port Pin Signal Name Port Pin RD P1.6 RD P1.6 WR P1.7 WR P1.7 ALE P1.5 D0 P4.0 D0/A0 P4.0 D1 P4.1 D1/A1 P4.1 D2 P4.2 D2/A2 P4.2 D3 P4.3 D3/A3 P4.3 D4 P4.4 D4/A4 P4.4 D5 P4.5 D5/A5 P4.5 D6 P4.6 D6/A6 P4.6 D7 P4.7 D7/A7 P4.7 A0 P3.0 A8 P3.0 A1 P3.1 A9 P3.1 A2 P3.2 A10 P3.2 A3 P3.3 A11 P3.3 A4 P3.4 A12 P3.4 A5 P3.5 A13 P3.5 A6 P3.6 A14 P3.6 A7 P3.7 A15 P3.7 A8 P2.0 — — A9 P2.1 — — A10 P2.2 — — A11 P2.3 — — A12 P2.4 — — A13 P2.5 — — A14 P2.6 — — A15 P2.7 Rev. 1.2 149

C8051F50x/F51x Table 18.2. EMIF Pinout (C8051F508/9-F510/1) Multiplexed Mode Signal Name Port Pin RD P1.6 WR P1.7 ALE P1.5 D0/A0 P3.0 D1/A1 P3.1 D2/A2 P3.2 D3/A3 P3.3 D4/A4 P3.4 D5/A5 P3.5 D6/A6 P3.6 D7/A7 P3.7 A8 P2.0 A9 P2.1 A10 P2.2 A11 P2.3 A12 P2.4 A13 P2.5 A14 P2.6 A15 P2.7 150 Rev. 1.2

C8051F50x/F51x SFR Definition 18.1. EMI0CN: External Memory Interface Control Bit 7 6 5 4 3 2 1 0 Name PGSEL[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xAA; SFR Page = 0x00 Bit Name Function 7:0 PGSEL[7:0] XRAM Page Select Bits. The XRAM Page Select Bits provide the high byte of the 16-bit external data memory address when using an 8-bit MOVX command, effectively selecting a 256-byte page of RAM. 0x00: 0x0000 to 0x00FF 0x01: 0x0100 to 0x01FF ... 0xFE: 0xFE00 to 0xFEFF 0xFF: 0xFF00 to 0xFFFF Rev. 1.2 151

C8051F50x/F51x SFR Definition 18.2. EMI0CF: External Memory Configuration Bit 7 6 5 4 3 2 1 0 Name EMD2 EMD[1:0] EALE[1:0] Type R/W Reset 0 0 0 0 0 0 1 1 SFR Address = 0xB2; SFR Page = 0x0F Bit Name Function 7:5 Unused Read = 000b; Write = Don’t Care. 4 EMD2 EMIF Multiplex Mode Select Bit. 0: EMIF operates in multiplexed address/data mode 1: EMIF operates in non-multiplexed mode (separate address and data pins) 3:2 EMD[1:0] EMIF Operating Mode Select Bits. 00: Internal Only: MOVX accesses on-chip XRAM only. All effective addresses alias to on-chip memory space 01: Split Mode without Bank Select: Accesses below the 4 kB boundary are directed on-chip. Accesses above the 4 kB boundary are directed off-chip. 8-bit off-chip MOVX operations use current contents of the Address high port latches to resolve the upper address byte. To access off chip space, EMI0CN must be set to a page that is not con- tained in the on-chip address space. 10: Split Mode with Bank Select: Accesses below the 4 kB boundary are directed on- chip. Accesses above the 4 kB boundary are directed off-chip. 8-bit off-chip MOVX operations uses the contents of EMI0CN to determine the high-byte of the address. 11: External Only: MOVX accesses off-chip XRAM only. On-chip XRAM is not visible to the CPU. 1:0 EALE[1:0] ALE Pulse-Width Select Bits. These bits only have an effect when EMD2 = 0. 00: ALE high and ALE low pulse width = 1 SYSCLK cycle. 01: ALE high and ALE low pulse width = 2 SYSCLK cycles. 10: ALE high and ALE low pulse width = 3 SYSCLK cycles. 11: ALE high and ALE low pulse width = 4 SYSCLK cycles. 152 Rev. 1.2

C8051F50x/F51x 18.4. Multiplexed and Non-multiplexed Selection The External Memory Interface is capable of acting in a Multiplexed mode or a Non-multiplexed mode, depending on the state of the EMD2 (EMI0CF.4) bit. 18.4.1. Multiplexed Configuration In Multiplexed mode, the Data Bus and the lower 8-bits of the Address Bus share the same Port pins: AD[7:0]. In this mode, an external latch (74HC373 or equivalent logic gate) is used to hold the lower 8-bits of the RAM address. The external latch is controlled by the ALE (Address Latch Enable) signal, which is driven by the External Memory Interface logic. An example of a Multiplexed Configuration is shown in Figure 18.1. In Multiplexed mode, the external MOVX operation can be broken into two phases delineated by the state of the ALE signal. During the first phase, ALE is high and the lower 8-bits of the Address Bus are pre- sented to AD[7:0]. During this phase, the address latch is configured such that the Q outputs reflect the states of the ‘D’ inputs. When ALE falls, signaling the beginning of the second phase, the address latch outputs remain fixed and are no longer dependent on the latch inputs. Later in the second phase, the Data Bus controls the state of the AD[7:0] port at the time RD or WR is asserted. See Section “18.6.2. Multiplexed Mode” on page 161 for more information. A[15:8] ADDRESS BUS A[15:8] 74HC373 E ALE G AD[7:0] ADDRESS/DATA BUS D Q A[7:0] M V 64 K X 8 DD I SRAM (Optional) 8 F I/O[7:0] CE /WR WE /RD OE Figure 18.1. Multiplexed Configuration Example Rev. 1.2 153

C8051F50x/F51x 18.4.2. Non-multiplexed Configuration In Non-multiplexed mode, the Data Bus and the Address Bus pins are not shared. An example of a Non- multiplexed Configuration is shown in Figure 18.2. See Section “18.6.1. Non-Multiplexed Mode” on page 158 for more information about Non-multiplexed operation. A[15:0] ADDRESS BUS A[15:0] E V DD M (Optional) 64 K X 8 8 I SRAM D[7:0] DATA BUS I/O[7:0] F CE /WR WE /RD OE Figure 18.2. Non-multiplexed Configuration Example 154 Rev. 1.2

C8051F50x/F51x 18.5. Memory Mode Selection The external data memory space can be configured in one of four modes, shown in Figure 18.3, based on the EMIF Mode bits in the EMI0CF register (SFR Definition 18.2). These modes are summarized below. More information about the different modes can be found in Section “18.6. Timing” on page 156. EMI0CF[3:2] = 00 EMI0CF[3:2] = 01 EMI0CF[3:2] = 10 EMI0CF[3:2] = 11 0xFFFF 0xFFFF 0xFFFF 0xFFFF On-Chip XRAM On-Chip XRAM Off-Chip Off-Chip Memory Memory (No Bank Select) (Bank Select) On-Chip XRAM Off-Chip Memory On-Chip XRAM On-Chip XRAM On-Chip XRAM On-Chip XRAM On-Chip XRAM 0x0000 0x0000 0x0000 0x0000 Figure 18.3. EMIF Operating Modes 18.5.1. Internal XRAM Only When bits EMI0CF[3:2] are set to 00, all MOVX instructions will target the internal XRAM space on the device. Memory accesses to addresses beyond the populated space will wrap on 4 kB boundaries. As an example, the addresses 0x1000 and 0x2000 both evaluate to address 0x0000 in on-chip XRAM space.  8-bit MOVX operations use the contents of EMI0CN to determine the high-byte of the effective address and R0 or R1 to determine the low-byte of the effective address.  16-bit MOVX operations use the contents of the 16-bit DPTR to determine the effective address. 18.5.2. Split Mode without Bank Select When bit EMI0CF.[3:2] are set to 01, the XRAM memory map is split into two areas, on-chip space and off- chip space.  Effective addresses below the internal XRAM size boundary will access on-chip XRAM space.  Effective addresses above the internal XRAM size boundary will access off-chip space.  8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on- chip or off-chip. However, in the “No Bank Select” mode, an 8-bit MOVX operation will not drive the upper 8-bits A[15:8] of the Address Bus during an off-chip access. This allows the user to manipulate the upper address bits at will by setting the Port state directly via the port latches. This behavior is in contrast with “Split Mode with Bank Select” described below. The lower 8-bits of the Address Bus A[7:0] are driven, determined by R0 or R1.  16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-chip or off-chip, and unlike 8-bit MOVX operations, the full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction. Rev. 1.2 155

C8051F50x/F51x 18.5.3. Split Mode with Bank Select When EMI0CF[3:2] are set to 10, the XRAM memory map is split into two areas, on-chip space and off- chip space.  Effective addresses below the internal XRAM size boundary will access on-chip XRAM space.  Effective addresses above the internal XRAM size boundary will access off-chip space.  8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on- chip or off-chip. The upper 8-bits of the Address Bus A[15:8] are determined by EMI0CN, and the lower 8-bits of the Address Bus A[7:0] are determined by R0 or R1. All 16-bits of the Address Bus A[15:0] are driven in “Bank Select” mode.  16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-chip or off-chip, and the full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction. 18.5.4. External Only When EMI0CF[3:2] are set to 11, all MOVX operations are directed to off-chip space. On-chip XRAM is not visible to the CPU. This mode is useful for accessing off-chip memory located between 0x0000 and the internal XRAM size boundary.  8-bit MOVX operations ignore the contents of EMI0CN. The upper Address bits A[15:8] are not driven (identical behavior to an off-chip access in “Split Mode without Bank Select” described above). This allows the user to manipulate the upper address bits at will by setting the Port state directly. The lower 8-bits of the effective address A[7:0] are determined by the contents of R0 or R1.  16-bit MOVX operations use the contents of DPTR to determine the effective address A[15:0]. The full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction. 18.6. Timing The timing parameters of the External Memory Interface can be configured to enable connection to devices having different setup and hold time requirements. The Address Setup time, Address Hold time, RD and WR strobe widths, and in multiplexed mode, the width of the ALE pulse are all programmable in units of SYSCLK periods through EMI0TC, shown in SFR Definition 18.3, and EMI0CF[1:0]. The timing for an off-chip MOVX instruction can be calculated by adding 4 SYSCLK cycles to the timing parameters defined by the EMI0TC register. Assuming non-multiplexed operation, the minimum execution time for an off-chip XRAM operation is 5 SYSCLK cycles (1 SYSCLK for RD or WR pulse + 4 SYSCLKs). For multiplexed operations, the Address Latch Enable signal will require a minimum of 2 additional SYSCLK cycles. Therefore, the minimum execution time for an off-chip XRAM operation in multiplexed mode is 7 SYSCLK cycles (2 for /ALE + 1 for RD or WR + 4). The programmable setup and hold times default to the maximum delay settings after a reset. Table 18.3 lists the ac parameters for the External Memory Interface, and Figure 18.4 through Figure 18.9 show the timing diagrams for the different External Memory Interface modes and MOVX operations. 156 Rev. 1.2

C8051F50x/F51x SFR Definition 18.3. EMI0TC: External Memory Timing Control Bit 7 6 5 4 3 2 1 0 Name EAS[1:0] EWR[3:0] EAH[1:0] Type R/W R/W R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xAA; SFR Page = 0x0F Bit Name Function 7:6 EAS[1:0] EMIF Address Setup Time Bits. 00: Address setup time = 0 SYSCLK cycles. 01: Address setup time = 1 SYSCLK cycle. 10: Address setup time = 2 SYSCLK cycles. 11: Address setup time = 3 SYSCLK cycles. 5:2 EWR[3:0] EMIF WR and RD Pulse-Width Control Bits. 0000: WR and RD pulse width = 1 SYSCLK cycle. 0001: WR and RD pulse width = 2 SYSCLK cycles. 0010: WR and RD pulse width = 3 SYSCLK cycles. 0011: WR and RD pulse width = 4 SYSCLK cycles. 0100: WR and RD pulse width = 5 SYSCLK cycles. 0101: WR and RD pulse width = 6 SYSCLK cycles. 0110: WR and RD pulse width = 7 SYSCLK cycles. 0111: WR and RD pulse width = 8 SYSCLK cycles. 1000: WR and RD pulse width = 9 SYSCLK cycles. 1001: WR and RD pulse width = 10 SYSCLK cycles. 1010: WR and RD pulse width = 11 SYSCLK cycles. 1011: WR and RD pulse width = 12 SYSCLK cycles. 1100: WR and RD pulse width = 13 SYSCLK cycles. 1101: WR and RD pulse width = 14 SYSCLK cycles. 1110: WR and RD pulse width = 15 SYSCLK cycles. 1111: WR and RD pulse width = 16 SYSCLK cycles. 1:0 EAH[1:0] EMIF Address Hold Time Bits. 00: Address hold time = 0 SYSCLK cycles. 01: Address hold time = 1 SYSCLK cycle. 10: Address hold time = 2 SYSCLK cycles. 11: Address hold time = 3 SYSCLK cycles. Rev. 1.2 157

C8051F50x/F51x 18.6.1. Non-Multiplexed Mode 18.6.1.1. 16-bit MOVX: EMI0CF[4:2] = 101, 110, or 111 Nonmuxed 16-bit WRITE ADDR[15:8] EMIF ADDRESS (8 MSBs) from DPH ADDR[7:0] EMIF ADDRESS (8 LSBs) from DPL DATA[7:0] EMIF WRITE DATA T T WDS WDH T T T ACS ACW ACH /WR /RD Nonmuxed 16-bit READ ADDR[15:8] EMIF ADDRESS (8 MSBs) from DPH ADDR[7:0] EMIF ADDRESS (8 LSBs) from DPL DATA[7:0] EMIF READ DATA T T RDS RDH T T T ACS ACW ACH /RD /WR Figure 18.4. Non-multiplexed 16-bit MOVX Timing 158 Rev. 1.2

C8051F50x/F51x 18.6.1.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = 101 or 111 Nonmuxed 8-bit WRITE without Bank Select ADDR[15:8] ADDR[7:0] EMIF ADDRESS (8 LSBs) from R0 or R1 DATA[7:0] EMIF WRITE DATA T T WDS WDH T T T ACS ACW ACH /WR /RD Nonmuxed 8-bit READ without Bank Select ADDR[15:8] ADDR[7:0] EMIF ADDRESS (8 LSBs) from R0 or R1 DATA[7:0] EMIF READ DATA T T RDS RDH T T T ACS ACW ACH /RD /WR Figure 18.5. Non-multiplexed 8-bit MOVX without Bank Select Timing Rev. 1.2 159

C8051F50x/F51x 18.6.1.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = 110 Nonmuxed 8-bit WRITE with Bank Select ADDR[15:8] EMIF ADDRESS (8 MSBs) from EMI0CN ADDR[7:0] EMIF ADDRESS (8 LSBs) from R0 or R1 DATA[7:0] EMIF WRITE DATA T T WDS WDH T T T ACS ACW ACH /WR /RD Nonmuxed 8-bit READ with Bank Select ADDR[15:8] EMIF ADDRESS (8 MSBs) from EMI0CN ADDR[7:0] EMIF ADDRESS (8 LSBs) from R0 or R1 DATA[7:0] EMIF READ DATA T T RDS RDH T T T ACS ACW ACH /RD /WR Figure 18.6. Non-multiplexed 8-bit MOVX with Bank Select Timing 160 Rev. 1.2

C8051F50x/F51x 18.6.2. Multiplexed Mode 18.6.2.1. 16-bit MOVX: EMI0CF[4:2] = 001, 010, or 011 Muxed 16-bit WRITE ADDR[15:8] EMIF ADDRESS (8 MSBs) from DPH EMIF ADDRESS (8 LSBs) from AD[7:0] EMIF WRITE DATA DPL T T ALEH ALEL ALE T T WDS WDH T T T ACS ACW ACH /WR /RD Muxed 16-bit READ ADDR[15:8] EMIF ADDRESS (8 MSBs) from DPH EMIF ADDRESS (8 LSBs) from AD[7:0] EMIF READ DATA DPL T T ALEH ALEL T T RDS RDH ALE T T T ACS ACW ACH /RD /WR Figure 18.7. Multiplexed 16-bit MOVX Timing Rev. 1.2 161

C8051F50x/F51x 18.6.2.2. 8-bit MOVX without Bank Select: EMI0CF[4:2] = 001 or 011 Muxed 8-bit WRITE Without Bank Select ADDR[15:8] EMIF ADDRESS (8 LSBs) from AD[7:0] EMIF WRITE DATA R0 or R1 T T ALEH ALEL ALE T T WDS WDH T T T ACS ACW ACH /WR /RD Muxed 8-bit READ Without Bank Select ADDR[15:8] EMIF ADDRESS (8 LSBs) from AD[7:0] EMIF READ DATA R0 or R1 T T ALEH ALEL T T RDS RDH ALE T T T ACS ACW ACH /RD /WR Figure 18.8. Multiplexed 8-bit MOVX without Bank Select Timing 162 Rev. 1.2

C8051F50x/F51x 18.6.2.3. 8-bit MOVX with Bank Select: EMI0CF[4:2] = 010 Muxed 8-bit WRITE with Bank Select ADDR[15:8] EMIF ADDRESS (8 MSBs) from EMI0CN EMIF ADDRESS (8 LSBs) from AD[7:0] EMIF WRITE DATA R0 or R1 T T ALEH ALEL ALE T T WDS WDH T T T ACS ACW ACH /WR /RD Muxed 8-bit READ with Bank Select ADDR[15:8] EMIF ADDRESS (8 MSBs) from EMI0CN EMIF ADDRESS (8 LSBs) from AD[7:0] EMIF READ DATA R0 or R1 T T ALEH ALEL T T RDS RDH ALE T T T ACS ACW ACH /RD /WR Figure 18.9. Multiplexed 8-bit MOVX with Bank Select Timing Rev. 1.2 163

C8051F50x/F51x Table 18.3. AC Parameters for External Memory Interface Parameter Description Min* Max* Units TACS Address/Control Setup Time 0 3 x TSYSCLK ns TACW Address/Control Pulse Width 1 x TSYSCLK 16 x TSYSCLK ns TACH Address/Control Hold Time 0 3 x TSYSCLK ns TALEH Address Latch Enable High Time 1 x TSYSCLK 4 x TSYSCLK ns TALEL Address Latch Enable Low Time 1 x TSYSCLK 4 x TSYSCLK ns TWDS Write Data Setup Time 1 x TSYSCLK 19 x TSYSCLK ns TWDH Write Data Hold Time 0 3 x TSYSCLK ns T Read Data Setup Time 20 ns RDS T Read Data Hold Time 0 ns RDH *Note: T is equal to one period of the device system clock (SYSCLK). SYSCLK 164 Rev. 1.2

C8051F50x/F51x 19. Oscillators and Clock Selection C8051F50x/F51x devices include a programmable internal high-frequency oscillator, an external oscillator drive circuit, and a clock multiplier. The internal oscillator can be enabled/disabled and calibrated using the OSCICN, OSCICRS, and OSCIFIN registers, as shown in Figure 19.1. The system clock can be sourced by the external oscillator circuit or the internal oscillator. The clock multiplier can produce three possible base outputs which can be scaled by a programmable factor of 1, 2/3, 2/4 (or 1/2), 2/5, 2/6 (or 1/3), or 2/7: Internal Oscillator x 2, Internal Oscillator x 4, External Oscillator x 2, or External Oscillator x 4. OSCICRS OSCIFIN OSCICN CLKSEL 10 CENCEN CN2CN1CN0 EL1EL0 SS FFF SS OO III II Option 3 XTAL2 CAL EN IOSC Programmable Internal n Option 4 Clock Generator XTAL2 CLOCK MULTIPLIER IOSC/2 Option 2 EXOSC x4 n SYSCLK EXOSC/2 VDD IOSC Option 1 XTAL1 XTAL2 10MΩ Input OSC Circuit EXOSC XTAL2 XTLVLDXOSCMD2XOSCMD1XOSCMD0 XFCN2XFCN1XFCN0 MULENMULINITMULRDYMULDIV2MULDIV1MULDIV0MULSEL1MULSEL0 OSCXCN CLKMUL Figure 19.1. Oscillator Options 19.1. System Clock Selection The CLKSL[1:0] bits in register CLKSEL select which oscillator source is used as the system clock. CLKSL[1:0] must be set to 01b for the system clock to run from the external oscillator; however the exter- nal oscillator may still clock certain peripherals (timers, PCA) when the internal oscillator is selected as the system clock. The system clock may be switched on-the-fly between the internal oscillator, external oscilla- tor, and Clock Multiplier so long as the selected clock source is enabled and has settled. The internal oscillator requires little start-up time and may be selected as the system clock immediately fol- lowing the register write which enables the oscillator. The external RC and C modes also typically require no startup time. External crystals and ceramic resonators however, typically require a start-up time before they are settled and ready for use. The Crystal Valid Flag (XTLVLD in register OSCXCN) is set to 1 by hardware when the external crystal or ceramic resonator is settled. In crystal mode, to avoid reading a false XTLVLD, soft- ware should delay at least 1 ms between enabling the external oscillator and checking XTLVLD. Rev. 1.2 165

C8051F50x/F51x SFR Definition 19.1. CLKSEL: Clock Select Bit 7 6 5 4 3 2 1 0 Name CLKSL[1:0] Type R R R R R R R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x8F; SFR Page = 0x0F; Bit Name Function 7:2 Unused Read = 000000b; Write = Don’t Care 1:0 CLKSL[1:0] System Clock Source Select Bits. 00: SYSCLK derived from the Internal Oscillator and scaled per the IFCN bits in reg- ister OSCICN. 01: SYSCLK derived from the External Oscillator circuit. 10: SYSCLK derived from the Clock Multiplier. 11: reserved. Important Note: If the selected system clock is greater than 25 MHz, please be aware of the following:  Flash Scale Timing must be configured for the faster system clock. See SFR Definition 15.3 for more details.  VDD and VDDA voltage must be 2 V or higher.  It is recommended to enable the VDD monitor as a reset source and configure it for the high threshold. See SFR Definition 17.1 for details on configuring the VDD monitor. If the VDD monitor is configured to the high threshold, the VDD and VDDA voltage must be greater than the VDD monitor high threshold. See Table 5.4 for VDD monitor threshold specifications. 166 Rev. 1.2

C8051F50x/F51x 19.2. Programmable Internal Oscillator All C8051F50x/F51x devices include a programmable internal high-frequency oscillator that defaults as the system clock after a system reset. The internal oscillator period can be adjusted via the OSCICRS and OSCIFIN registers defined in SFR Definition 19.3 and SFR Definition 19.4. On C8051F50x/F51x devices, OSCICRS and OSCIFIN are factory calibrated to obtain a 24 MHz base frequency. Note that the system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, 8, 16, 32, 64, or 128, as defined by the IFCN bits in register OSCICN. The divide value defaults to 128 following a reset. 19.2.1. Internal Oscillator Suspend Mode When software writes a logic 1 to SUSPEND (OSCICN.5), the internal oscillator is suspended. If the sys- tem clock is derived from the internal oscillator, the input clock to the peripheral or CIP-51 will be stopped until one of the following events occur:  Port 0 Match Event.  Port 1 Match Event.  Port 2 Match Event.  Port 3 Match Event.  Comparator 0 enabled and output is logic 0. When one of the oscillator awakening events occur, the internal oscillator, CIP-51, and affected peripherals resume normal operation, regardless of whether the event also causes an interrupt. The CPU resumes execution at the instruction following the write to SUSPEND. Note: When entering suspend mode, firmware must set the ZTCEN bit in REF0CN (SFR Definition 8.1). Rev. 1.2 167

C8051F50x/F51x SFR Definition 19.2. OSCICN: Internal Oscillator Control Bit 7 6 5 4 3 2 1 0 Name IOSCEN[1:0] SUSPEND IFRDY Reserved IFCN[2:0] Type R/W R/W R/W R R R/W Reset 1 1 0 1 0 0 0 0 SFR Address = 0xA1; SFR Page = 0x0F; Bit Name Function 7:6 IOSCEN[1:0] Internal Oscillator Enable Bits. 00: Oscillator Disabled. 01: Reserved. 10: Reserved. 11: Oscillator enabled in normal mode and disabled in suspend mode. 5 SUSPEND Internal Oscillator Suspend Enable Bit. Setting this bit to logic 1 places the internal oscillator in SUSPEND mode. The inter- nal oscillator resumes operation when one of the SUSPEND mode awakening events occurs. 4 IFRDY Internal Oscillator Frequency Ready Flag. 0: Internal oscillator is not running at programmed frequency. 1: Internal oscillator is running at programmed frequency. 3 Reserved Read = 0b; Must Write = 0b. 2:0 IFCN[2:0] Internal Oscillator Frequency Divider Control Bits. 000: SYSCLK derived from Internal Oscillator divided by 128. 001: SYSCLK derived from Internal Oscillator divided by 64. 010: SYSCLK derived from Internal Oscillator divided by 32. 011: SYSCLK derived from Internal Oscillator divided by 16. 100: SYSCLK derived from Internal Oscillator divided by 8. 101: SYSCLK derived from Internal Oscillator divided by 4. 110: SYSCLK derived from Internal Oscillator divided by 2. 111: SYSCLK derived from Internal Oscillator divided by 1. 168 Rev. 1.2

C8051F50x/F51x SFR Definition 19.3. OSCICRS: Internal Oscillator Coarse Calibration Bit 7 6 5 4 3 2 1 0 Name OSCICRS[6:0] Type R R/W Reset 0 Varies Varies Varies Varies Varies Varies Varies SFR Address = 0xA2; SFR Page = 0x0F; Bit Name Function 7 Unused Read = 0; Write = Don’t Care 6:0 OSCICRS[6:0] Internal Oscillator Coarse Calibration Bits. These bits determine the internal oscillator period. When set to 0000000b, the internal oscillator operates at its slowest setting. When set to 1111111b, the inter- nal oscillator operates at its fastest setting. The reset value is factory calibrated to generate an internal oscillator frequency of 24 MHz. SFR Definition 19.4. OSCIFIN: Internal Oscillator Fine Calibration Bit 7 6 5 4 3 2 1 0 OSCIFIN[5:0] Type R R R/W Reset 0 0 Varies Varies Varies Varies Varies Varies SFR Address = 0x9E; SFR Page = 0x0F; Bit Name Function 7:6 Unused Read = 00b; Write = Don’t Care 5:0 OSCIFIN[5:0] Internal Oscillator Fine Calibration Bits. These bits are fine adjustment for the internal oscillator period. The reset value is factory calibrated to generate an internal oscillator frequency of 24 MHz. Rev. 1.2 169

C8051F50x/F51x 170 Rev. 1.2

C8051F50x/F51x 19.3. Clock Multiplier The Clock Multiplier generates an output clock which is 4 times the input clock frequency scaled by a pro- grammable factor of 1, 2/3, 2/4 (or 1/2), 2/5, 2/6 (or 1/3), or 2/7. The Clock Multiplier’s input can be selected from the external oscillator, or the internal or external oscillators divided by 2. This produces three possible base outputs which can be scaled by a programmable factor: Internal Oscillator x 2, External Oscillator x 2, or External Oscillator x 4. See Section 19.1 on page 165 for details on system clock selec- tion. The Clock Multiplier is configured via the CLKMUL register (SFR Definition 19.5). The procedure for con- figuring and enabling the Clock Multiplier is as follows: 1. Reset the Multiplier by writing 0x00 to register CLKMUL. 2. Select the Multiplier input source via the MULSEL bits. 3. Select the Multiplier output scaling factor via the MULDIV bits 4. Enable the Multiplier with the MULEN bit (CLKMUL | = 0x80). 5. Delay for >5 µs. 6. Initialize the Multiplier with the MULINIT bit (CLKMUL | = 0xC0). 7. Poll for MULRDY => 1. Important Note: When using an external oscillator as the input to the Clock Multiplier, the external source must be enabled and stable before the Multiplier is initialized. See “19.4. External Oscillator Drive Circuit” on page 172 for details on selecting an external oscillator source. The Clock Multiplier allows faster operation of the CIP-51 core and is intended to generate an output fre- quency between 25 and 50 MHz. The clock multiplier can also be used with slow input clocks. However, if the clock is below the minimum Clock Multiplier input frequency (FCMmin), the generated clock will consist of four fast pulses followed by a long delay until the next input clock rising edge. The average frequency of the output is equal to 4x the input, but the instantaneous frequency may be faster. See Figure 19.2 below for more information. if F >= F CM i n CMmin F CM i n F CM o ut if F < F CMi n CMmin F CM i n F CM o ut Figure 19.2. Example Clock Multiplier Output Rev. 1.2 170

C8051F50x/F51x SFR Definition 19.5. CLKMUL: Clock Multiplier Bit 7 6 5 4 3 2 1 0 Name MULEN MULINIT MULRDY MULDIV[2:0] MULSEL[1:0] Type R/W R/W R R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x97; SFR Page = 0x0F; Bit Name Function 7 MULEN Clock Multiplier Enable. 0: Clock Multiplier disabled. 1: Clock Multiplier enabled. 6 MULINIT Clock Multiplier Initialize. This bit is 0 when the Clock Multiplier is enabled. Once enabled, writing a 1 to this bit will initialize the Clock Multiplier. The MULRDY bit reads 1 when the Clock Mul- tiplier is stabilized. 5 MULRDY Clock Multiplier Ready. 0: Clock Multiplier is not ready. 1: Clock Multiplier is ready (PLL is locked). 4:2 MULDIV[2:0] Clock Multiplier Output Scaling Factor. 000: Clock Multiplier Output scaled by a factor of 1. 001: Clock Multiplier Output scaled by a factor of 1. 010: Clock Multiplier Output scaled by a factor of 1. 011: Clock Multiplier Output scaled by a factor of 2/3*. 100: Clock Multiplier Output scaled by a factor of 2/4 (1/2). 101: Clock Multiplier Output scaled by a factor of 2/5*. 110: Clock Multiplier Output scaled by a factor of 2/6 (1/3). 111: Clock Multiplier Output scaled by a factor of 2/7*. *Note: The Clock Multiplier output duty cycle is not 50% for these settings. 1:0 MULSEL[1:0] Clock Multiplier Input Select. These bits select the clock supplied to the Clock Multiplier Clock Multiplier Output MULSEL[1:0] Selected Input Clock for MULDIV[2:0] = 000b 00 Internal Oscillator Internal Oscillator x 2 01 External Oscillator External Oscillator x 2 10 Internal Oscillator Internal Oscillator x 4 11 External Oscillator External Oscillator x 4 Notes:The maximum system clock is 50 MHz, and so the Clock Multiplier output should be scaled accordingly. If Internal Oscillator x 2 or External Oscillator x 2 is selected using the MULSEL bits, MULDIV[2:0] is ignored. 171 Rev. 1.2

C8051F50x/F51x 19.4. External Oscillator Drive Circuit The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crys- tal/resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 19.1. A 10 MΩ resistor also must be wired across the XTAL2 and XTAL1 pins for the crystal/resonator configura- tion. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 pin as shown in Option 2, 3, or 4 of Figure 19.1. The type of external oscillator must be selected in the OSCXCN register, and the frequency control bits (XFCN) must be selected appropriately (see SFR Definition 19.6). Important Note on External Oscillator Usage: Port pins must be configured when using the external oscillator circuit. When the external oscillator drive circuit is enabled in crystal/resonator mode, Port pins P0.2 and P0.3 are used as XTAL1 and XTAL2 respectively. When the external oscillator drive circuit is enabled in capacitor, RC, or CMOS clock mode, Port pin P0.3 is used as XTAL2. The Port I/O Crossbar should be configured to skip the Port pins used by the oscillator circuit; see Section “20.3. Priority Crossbar Decoder” on page 180 for Crossbar configuration. Additionally, when using the external oscillator circuit in crystal/resonator, capacitor, or RC mode, the associated Port pins should be configured as analog inputs. In CMOS clock mode, the associated pin should be configured as a digital input. See Section “20.4. Port I/O Initialization” on page 182 for details on Port input mode selection. Rev. 1.2 172

C8051F50x/F51x SFR Definition 19.6. OSCXCN: External Oscillator Control Bit 7 6 5 4 3 2 1 0 Name XTLVLD XOSCMD[2:0] XFCN[2:0] Type R R/W R R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x9F; SFR Page = 0x0F; Bit Name Function 7 XTLVLD Crystal Oscillator Valid Flag. (Read only when XOSCMD = 11x.) 0: Crystal Oscillator is unused or not yet stable. 1: Crystal Oscillator is running and stable. 6:4 XOSCMD[2:0] External Oscillator Mode Select. 00x: External Oscillator circuit off. 010: External CMOS Clock Mode. 011: External CMOS Clock Mode with divide by 2 stage. 100: RC Oscillator Mode. 101: Capacitor Oscillator Mode. 110: Crystal Oscillator Mode. 111: Crystal Oscillator Mode with divide by 2 stage. 3 Unused Read = 0b; Write =0b 2:0 XFCN[2:0] External Oscillator Frequency Control Bits. Set according to the desired frequency for Crystal or RC mode. Set according to the desired K Factor for C mode. XFCN Crystal Mode RC Mode C Mode 000 f ≤ 32 kHz f ≤ 25 kHz K Factor = 0.87 001 32 kHz < f ≤ 84 kHz 25 kHz < f ≤ 50 kHz K Factor = 2.6 010 84 kHz < f ≤ 225 kHz 50 kHz < f ≤ 100 kHz K Factor = 7.7 011 225 kHz < f ≤ 590 kHz 100 kHz < f ≤ 200 kHz K Factor = 22 100 590 kHz < f ≤ 1.5 MHz 200 kHz < f ≤ 400 kHz K Factor = 65 101 1.5 MHz < f ≤ 4 MHz 400 kHz < f ≤ 800 kHz K Factor = 180 110 4 MHz < f ≤ 10 MHz 800 kHz < f ≤ 1.6 MHz K Factor = 664 111 10 MHz < f ≤ 30 MHz 1.6 MHz < f ≤ 3.2 MHz K Factor = 1590 173 Rev. 1.2

C8051F50x/F51x 19.4.1. External Crystal Example If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be configured as shown in Figure 19.1, Option 1. The External Oscillator Frequency Control value (XFCN) should be chosen from the Crystal column of the table in SFR Definition 19.6 (OSCXCN register). For example, an 11.0592 MHz crystal requires an XFCN setting of 111b and a 32.768 kHz Watch Crystal requires an XFCN setting of 001b. After an external 32.768 kHz oscillator is stabilized, the XFCN setting can be switched to 000 to save power. It is recommended to enable the missing clock detector before switching the system clock to any external oscillator source. When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The rec- ommended procedure is: 1. Force XTAL1 and XTAL2 to a high state. This involves enabling the Crossbar and writing 1 to the port pins associated with XTAL1 and XTAL2. 2. Configure XTAL1 and XTAL2 as analog inputs using. 3. Enable the external oscillator. 4. Wait at least 1 ms. 5. Poll for XTLVLD => 1. 6. Enable the Missing Clock Detector. 7. Switch the system clock to the external oscillator. Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as short as possible and shielded with ground plane from any other traces which could introduce noise or interference. The capacitors shown in the external crystal configuration provide the load capacitance required by the crystal for correct oscillation. These capacitors are "in series" as seen by the crystal and "in parallel" with the stray capacitance of the XTAL1 and XTAL2 pins. Note: The desired load capacitance depends upon the crystal and the manufacturer. Refer to the crystal data sheet when completing these calculations. For example, a tuning-fork crystal of 32.768 kHz with a recommended load capacitance of 12.5 pF should use the configuration shown in Figure 19.1, Option 1. The total value of the capacitors and the stray capac- itance of the XTAL pins should equal 25 pF. With a stray capacitance of 3 pF per pin, the 22 pF capacitors yield an equivalent capacitance of 12.5 pF across the crystal, as shown in Figure 19.3. Rev. 1.2 174

C8051F50x/F51x XTAL1 10MΩ XTAL2 32.768 kHz 22pF* 22pF* * Capacitor values depend on crystal specifications Figure 19.3. External 32.768 kHz Quartz Crystal Oscillator Connection Diagram 19.4.2. External RC Example If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as shown in Figure 19.1, Option 2. The capacitor should be no greater than 100 pF; however for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To deter- mine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first select the RC network value to produce the desired frequency of oscillation, according to Equation , where f = the frequency of oscillation in MHz, C = the capacitor value in pF, and R = the pull-up resistor value in kΩ. f = 1.23× 103⁄(R× C) Equation 19.1. RC Mode Oscillator Frequency For example: If the frequency desired is 100 kHz, let R = 246 kΩ and C = 50 pF: f = 1.23(103)/RC = 1.23(103)/[246 x 50] = 0.1 MHz = 100 kHz Referring to the table in SFR Definition 19.6, the required XFCN setting is 010b. 19.4.3. External Capacitor Example If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in Figure 19.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capaci- tor to be used and find the frequency of oscillation according to Equation 19.2, where f = the frequency of oscillation in MHz, C = the capacitor value in pF, and V = the MCU power supply in Volts. DD 175 Rev. 1.2

C8051F50x/F51x Equation 19.2. C Mode Oscillator Frequency f = (KF) ⁄(R× V ) DD For example: Assume V = 2.1 V and f = 75 kHz: DD f = KF / (C x VDD) 0.075 MHz = KF / (C x 2.1) Since the frequency of roughly 75 kHz is desired, select the K Factor from the table in SFR Definition 19.6 (OSCXCN) as KF = 7.7: 0.075 MHz = 7.7 / (C x 2.1) C x 2.1 = 7.7 / 0.075 MHz C = 102.6 / 2.0 pF = 51.3 pF Therefore, the XFCN value to use in this example is 010b. Rev. 1.2 176

C8051F50x/F51x 20. Port Input/Output Digital and analog resources are available through 40 (C8051F500/1/4/5), 33 (C8051F508/9-F510/1) or 25 (C8051F502/3/6/7) I/O pins. Port pins P0.0-P4.7 on the C8051F500/1/4/5, port pins P0.0-P4.0 on theC8051F508/9-F510/1, and port pins P0.0-P3.0 on the C8051F502/3/6/7 can be defined as general-pur- pose I/O (GPIO), assigned to one of the internal digital resources, or assigned to an analog function as shown in Figure 20.3. Port pin P4.0 on the C8051F508/9-F510/1 can be used as GPIO and is shared with the C2 Interface Data signal (C2D). Similarly, port pin P3.0 is shared with C2D on the C8051F502/3/6/7. The designer has complete control over which functions are assigned, limited only by the number of phys- ical I/O pins. This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. Note that the state of a Port I/O pin can always be read in the corresponding Port latch, regard- less of the Crossbar settings. The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder (Figure 20.3 and Figure 20.4). The registers XBR0, XBR1, XBR2 are defined in SFR Definition 20.1 and SFR Definition 20.2 and are used to select internal digital functions. All Port I/Os are 5 V tolerant (refer to Figure 20.2 for the Port cell circuit). The Port I/O cells are configured as either push-pull or open-drain in the Port Output Mode registers (PnMDOUT, where n = 0,1). Complete Electrical Specifications for Port I/O are given in Table 5.3 on page 45. XBR0, XBR1, PnMDOUT, XBR2, PnSKIP PnDMIN Registers External Priority Pins Decoder Highest UART0 2 8 IP/O0 P0.0 HPirgiohreitsyt Priority 2 Cells P0.7 CAN0 4 SPI0 Digital Crossbar 8 P1 P1.0 2 I/O s) SMBus0 Cells P1.7 al Sign CP0 2 Digital CP1 2 8 IP/O2 P2.0 nal Cells P2.7 er /SYSCLK nt (I 7 PCA0 8 P3 P3.0 I/O T0, T1, 4 Cells P3.7 /INT0, /INT1 Lowest 2 Priority LIN0 8 P4 P4.0 8 x 5 I/O Lowest Cells P4.7 Priority P0 Port P1 (Px.0-Px.7) Latches P2 P3 8 x 5 PnMASK P4 PnMATCH Registers Figure 20.1. Port I/O Functional Block Diagram Rev. 1.2 177

C8051F50x/F51x 20.1. Port I/O Modes of Operation Port pins P0.0–P4.7 use the Port I/O cell shown in Figure 20.2. Each Port I/O cell can be configured by software for analog I/O or digital I/O using the PnMDIN registers. On reset, all Port I/O cells default to a high impedance state with weak pull-ups enabled until the Crossbar is enabled (XBARE = 1). 20.1.1. Port Pins Configured for Analog I/O Any pins to be used as Comparator or ADC inputs, external oscillator inputs, or VREF should be config- ured for analog I/O (PnMDIN.n = 0). When a pin is configured for analog I/O, its weak pullup, digital driver, and digital receiver are disabled. Port pins configured for analog I/O will always read back a value of 0. Configuring pins as analog I/O saves power and isolates the Port pin from digital interference. Port pins configured as digital inputs may still be used by analog peripherals; however, this practice is not recom- mended and may result in measurement errors. 20.1.2. Port Pins Configured For Digital I/O Any pins to be used by digital peripherals (UART, SPI, SMBus, etc.), external digital event capture func- tions, or as GPIO should be configured as digital I/O (PnMDIN.n = 1). For digital I/O pins, one of two output modes (push-pull or open-drain) must be selected using the PnMDOUT registers. Push-pull outputs (PnMDOUT.n = 1) drive the Port pad to the VIO or GND supply rails based on the output logic value of the Port pin. Open-drain outputs have the high side driver disabled; therefore, they only drive the Port pad to GND when the output logic value is 0 and become high impedance inputs (both high low drivers turned off) when the output logic value is 1. When a digital I/O cell is placed in the high impedance state, a weak pull-up transistor pulls the Port pad to the VIO supply voltage to ensure the digital input is at a defined logic state. Weak pull-ups are disabled when the I/O cell is driven to GND to minimize power consumption and may be globally disabled by setting WEAKPUD to 1. The user should ensure that digital I/O are always internally or externally pulled or driven to a valid logic state to minimize power consumption. Port pins configured for digital I/O always read back the logic state of the Port pad, regardless of the output logic value of the Port pin. WEAKPUD (Weak Pull-Up Disable) PxMDOUT.x (1 for push-pull) VIO VIO (0 for open-drain) XBARE (WEAK) (Crossbar Enable) PORT Px.x – Output PAD Logic Value (Port Latch or Crossbar) PxMDIN.x GND (1 for digital) (0 for analog) To/From Analog Peripheral Px.x – Input Logic Value (Reads 0 when pin is configured as an analog I/O) Figure 20.2. Port I/O Cell Block Diagram 178 Rev. 1.2

C8051F50x/F51x 20.1.3. Interfacing Port I/O in a Multi-Voltage System All Port I/O are capable of interfacing to digital logic operating at a supply voltage higher than VDD and less than 5.25 V. Connect the VIO pin to the voltage source of the interface logic. 20.2. Assigning Port I/O Pins to Analog and Digital Functions Port I/O pins P0.0–P3.7 can be assigned to various analog, digital, and external interrupt functions. P4.0- P4.7 can be assigned to only digital functions. The Port pins assigned to analog functions should be con- figured for analog I/O, and Port pins assigned to digital or external interrupt functions should be configured for digital I/O. 20.2.1. Assigning Port I/O Pins to Analog Functions Table 20.1 shows all available analog functions that require Port I/O assignments. Port pins selected for these analog functions should have their corresponding bit in PnSKIP set to 1. This reserves the pin for use by the analog function and does not allow it to be claimed by the Crossbar. Table 20.1 shows the potential mapping of Port I/O to each analog function. Table 20.1. Port I/O Assignment for Analog Functions Analog Function Potentially Assignable SFR(s) used for Port Pins Assignment ADC Input P0.0–P3.7* ADC0MX, PnSKIP Comparator0 or Compartor1 Input P0.0–P2.7 CPT0MX, CPT1MX, PnSKIP Voltage Reference (VREF0) P0.0 REF0CN, PnSKIP External Oscillator in Crystal Mode (XTAL1) P0.2 OSCXCN, PnSKIP External Oscillator in RC, C, or Crystal Mode (XTAL2) P0.3 OSCXCN, PnSKIP *Note: P3.1–P3.7 are only available on the 48-pin and 40-pin packages 20.2.2. Assigning Port I/O Pins to Digital Functions Any Port pins not assigned to analog functions may be assigned to digital functions or used as GPIO. Most digital functions rely on the Crossbar for pin assignment; however, some digital functions bypass the Crossbar in a manner similar to the analog functions listed above. Port pins used by these digital func- tions and any Port pins selected for use as GPIO should have their corresponding bit in PnSKIP set to 1. Table 20.2 shows all available digital functions and the potential mapping of Port I/O to each digital function. Table 20.2. Port I/O Assignment for Digital Functions Digital Function Potentially Assignable Port Pins SFR(s) used for Assignment UART0, SPI0, SMBus, Any Port pin available for assignment by the XBR0, XBR1, XBR2 CAN0, LIN0, CP0, CP0A, Crossbar. This includes P0.0–P4.7* pins which CP1, CP1A, SYSCLK, PCA0 have their PnSKIP bit set to 0. (CEX0-5 and ECI), T0 or T1. Note: The Crossbar will always assign UART0 pins to P0.4 and P0.5 and always assign CAN0 to P0.6 and P0.7. Any pin used for GPIO P0.0–P4.7* P0SKIP, P1SKIP, P2SKIP, P3SKIP *Note: P3.1–P3.7 and P4.0 are only available on the 48-pin and 40pin packages. P4.1–P4.7 are only available on the 48-pin package. A skip register is not available for P4. Rev. 1.2 179

C8051F50x/F51x 20.2.3. Assigning Port I/O Pins to External Digital Event Capture Functions External digital event capture functions can be used to trigger an interrupt or wake the device from a low power mode when a transition occurs on a digital I/O pin. The digital event capture functions do not require dedicated pins and will function on both GPIO pins (PnSKIP = 1) and pins in use by the Crossbar (PnSKIP = 0). External digital event capture functions cannot be used on pins configured for analog I/O. Table 20.3 shows all available external digital event capture functions. Table 20.3. Port I/O Assignment for External Digital Event Capture Functions Digital Function Potentially Assignable Port Pins SFR(s) used for Assignment External Interrupt 0 P1.0–P1.7 IT01CF External Interrupt 1 P1.0–P1.7 IT01CF Port Match P0.0–P3.7* P0MASK, P0MAT P1MASK, P1MAT P2MASK, P2MAT P3MASK, P3MAT *Note: P3.1–P3.7 are only available on the 48-pin packages. 20.3. Priority Crossbar Decoder The Priority Crossbar Decoder (Figure 20.3) assigns a priority to each I/O function, starting at the top with UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that resource excluding UART0, which is always assigned to pins P0.4 and P0.5, and excluding CAN0 which is always assigned to pins P0.6 and P0.7. If a Port pin is assigned, the Crossbar skips that pin when assign- ing the next selected resource. Additionally, the Crossbar will skip Port pins whose associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that are to be used for analog input, dedicated functions, or GPIO. Because of the nature of Priority Crossbar Decoder, not all peripherals can be located on all port pins. Figure 20.3 maps peripherals to the potential port pins on which the peripheral I/O can appear. Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the Crossbar, its corresponding PnSKIP bit should be set. This applies to P0.0 if VREF is used, P0.1 if the ADC is configured to use the external conversion start signal (CNVSTR), P0.3 and/or P0.2 if the external oscillator circuit is enabled, and any selected ADC or Comparator inputs. The Crossbar skips selected pins as if they were already assigned, and moves to the next unassigned pin. 180 Rev. 1.2

C8051F50x/F51x Port P0 P1 P2 P3 P4 SFupnecctiiaoln VREFNVSTRXTAL1XTAL2 ALE/RD /WR aPavna3di.l1a 4-bP0le-3p .oi7nn, pPtah4ce.k 04a 8og-neplsiyn avaPpil4ian.b1 pl-ePa co4kn.7a t ghoeens ly4 8- Signals C PIN I/O 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 UART_TX UART_RX CAN_TX CAN_RX SCK MISO MOSI NSS SDA SCL CP0 CP0A CP1 CP1A SYSCLK CEX0 CEX1 CEX2 CEX3 CEX4 CEX5 ECI T0 T1 LIN_TX LIN_RX Figure 20.3. Peripheral Availability on Port I/O Pins Registers XBR0, XBR1, and XBR2 are used to assign the digital I/O resources to the physical I/O Port pins. Note that when the SMBus is selected, the Crossbar assigns both pins associated with the SMBus (SDA and SCL); and similarly when the UART, CAN or LIN are selected, the Crossbar assigns both pins associated with the peripheral (TX and RX). UART0 pin assignments are fixed for bootloading purposes: UART TX0 is always assigned to P0.4; UART RX0 is always assigned to P0.5. CAN0 pin assignments are fixed to P0.6 for CAN_TX and P0.7 for CAN_RX. Standard Port I/Os appear contiguously after the priori- tized functions have been assigned. Important Note: The SPI can be operated in either 3-wire or 4-wire modes, pending the state of the NSS- MD1–NSSMD0 bits in register SPI0CN. According to the SPI mode, the NSS signal may or may not be routed to a Port pin. As an example configuration, if CAN0, SPI0 in 4-wire mode, and PCA0 Modules 0, 1, and 2 are enabled on the crossbar with P0.1, P0.2, and P0.5 skipped, the registers should be set as follows: XBR0 = 0x06 (CAN0 and SPI0 enabled), XBR1 = 0x0C (PCA0 modules 0, 1, and 2 enabled), XBR2 = 0x40 (Crossbar enabled), and P0SKIP = 0x26 (P0.1, P0.2, and P0.5 skipped). The resulting crossbar would look as shown in Figure 20.4. Rev. 1.2 181

C8051F50x/F51x Port P0 P1 P2 P3 P4 R SFupnecctiiaoln VREF CNVST XTAL1 XTAL2 ALE /RD /WR aPavna3di.l1 a4-bP0le-3p .oi7nn, pPtha4ce.k 04a 8og-neplsiyn avaPpi4lian.b1 pl-ePa co4k.n7a t ghoeens ly4 8- Signals PIN I/O 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 UART_TX UART_RX CAN_TX CAN_RX SCK MISO MOSI NSS *NSS Is only pinned out in 4-wire SPI Mode SDA SCL CP0 CP0A CP1 CP1A SYSCLK CEX0 CEX1 CEX2 CEX3 CEX4 CEX5 ECI T0 T1 LIN_TX LIN_RX 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 P0SKIP[0:7] P1SKIP[0:7] P2SKIP[0:7] P3SKIP[0:7] Figure 20.4. Crossbar Priority Decoder in Example Configuration 20.4. Port I/O Initialization Port I/O initialization consists of the following steps: 1. Select the input mode (analog or digital) for all Port pins, using the Port Input Mode register (PnMDIN). 2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port Output Mode register (PnMDOUT). 3. Select any pins to be skipped by the I/O Crossbar using the Port Skip registers (PnSKIP). 4. Assign Port pins to desired peripherals. 5. Enable the Crossbar (XBARE = 1). All Port pins must be configured as either analog or digital inputs. Port 4 on the C8051F500/1/4/5 and C8051F508/9-F510/1 is a digital-only Port. Any pins to be used as Comparator or ADC inputs should be configured as an analog inputs. When a pin is configured as an analog input, its weak pullup, digital driver, and digital receiver are disabled. This process saves power and reduces noise on the analog input. Pins configured as digital inputs may still be used by analog peripherals; however this practice is not recom- mended. Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a 1 indicates a digital input, and a 0 indicates an analog input. All pins default to digital inputs on reset. See SFR Definition 182 Rev. 1.2

C8051F50x/F51x 20.13 for the PnMDIN register details. The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMD- OUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is required even for the digital resources selected in the XBRn registers, and is not automatic. The only exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the PnMDOUT settings. When the WEAKPUD bit in XBR2 is 0, a weak pullup is enabled for all Port I/O config- ured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pullup is turned off on an output that is driving a 0 to avoid unnecessary power dissipation. Registers XBR0, XBR1, and XBR2 must be loaded with the appropriate values to select the digital I/O functions required by the design. Setting the XBARE bit in XBR2 to 1 enables the Crossbar. Until the Crossbar is enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode Table; as an alternative, the Configuration Wizard utility of the Silicon Labs IDE software will deter- mine the Port I/O pin-assignments based on the XBRn Register settings. The Crossbar must be enabled to use Port pins as standard Port I/O in output mode. Port output drivers are disabled while the Crossbar is disabled. Rev. 1.2 183

C8051F50x/F51x SFR Definition 20.1. XBR0: Port I/O Crossbar Register 0 Bit 7 6 5 4 3 2 1 0 Name CP1AE CP1E CP0AE CP0E SMB0E SPI0E CAN0E URT0E Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xE1; SFR Page = 0x0F Bit Name Function 7 CP1AE Comparator1 Asynchronous Output Enable. 0: Asynchronous CP1 unavailable at Port pin. 1: Asynchronous CP1 routed to Port pin. 6 CP1E Comparator1 Output Enable. 0: CP1 unavailable at Port pin. 1: CP1 routed to Port pin. 5 CP0AE Comparator0 Asynchronous Output Enable. 0: Asynchronous CP0 unavailable at Port pin. 1: Asynchronous CP0 routed to Port pin. 4 CP0E Comparator0 Output Enable. 0: CP0 unavailable at Port pin. 1: CP0 routed to Port pin. 3 SMB0E SMBus I/O Enable. 0: SMBus I/O unavailable at Port pins. 1: SMBus I/O routed to Port pins. 2 SPI0E SPI I/O Enable. 0: SPI I/O unavailable at Port pins. 1: SPI I/O routed to Port pins. Note that the SPI can be assigned either 3 or 4 GPIO pins. 1 CAN0E CAN I/O Output Enable. 0: CAN I/O unavailable at Port pins. 1: CAN_TX, CAN_RX routed to Port pins P0.6 and P0.7. 0 URT0E UART I/O Output Enable. 0: UART I/O unavailable at Port pin. 1: UART TX0, RX0 routed to Port pins P0.4 and P0.5. 184 Rev. 1.2

C8051F50x/F51x SFR Definition 20.2. XBR1: Port I/O Crossbar Register 1 Bit 7 6 5 4 3 2 1 0 Name T1E T0E ECIE PCA0ME[2:0] SYSCKE Reserved Type R/W R/W R/W R/W R/W R R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xE2; SFR Page = 0x0F Bit Name Function 7 T1E T1 Enable. 0: T1 unavailable at Port pin. 1: T1 routed to Port pin. 6 T0E T0 Enable. 0: T0 unavailable at Port pin. 1: T0 routed to Port pin. 5 ECIE PCA0 External Counter Input Enable. 0: ECI unavailable at Port pin. 1: ECI routed to Port pin. 4:2 PCA0ME[2:0] PCA Module I/O Enable Bits. 000: All PCA I/O unavailable at Port pins. 001: CEX0 routed to Port pin. 010: CEX0, CEX1 routed to Port pins. 011: CEX0, CEX1, CEX2 routed to Port pins. 100: CEX0, CEX1, CEX2, CEX3 routed to Port pins. 101: CEX0, CEX1, CEX2, CEX3, CEX4 routed to Port pins. 110: CEX0, CEX1, CEX2, CEX3, CEX4, CEX5 routed to Port pins. 111: Reserved 1 SYSCKE SYSCLK Output Enable. 0: SYSCLK unavailable at Port pin. 1: SYSCLK output routed to Port pin. 0 Reserved Always Write to 0. Rev. 1.2 185

C8051F50x/F51x SFR Definition 20.3. XBR2: Port I/O Crossbar Register 1 Bit 7 6 5 4 3 2 1 0 Name WEAKPUD XBARE Reserved LIN0E Type R/W R/W R/W R/W R/W R R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xC7; SFR Page = 0x0F Bit Name Function 7 WEAKPUD Port I/O Weak Pullup Disable. 0: Weak Pullups enabled (except for Ports whose I/O are configured for analog mode). 1: Weak Pullups disabled. 6 XBARE Crossbar Enable. 0: Crossbar disabled. 1: Crossbar enabled. 5:1 Reserved Always Write to 00000b. 0 LIN0E LIN I/O Output Enable. 0: LIN I/O unavailable at Port pin. 1: LIN_TX, LIN_RX routed to Port pins. 186 Rev. 1.2

C8051F50x/F51x 20.5. Port Match Port match functionality allows system events to be triggered by a logic value change on P0, P1, P2 or P3. A software controlled value stored in the PnMATCH registers specifies the expected or normal logic values of P0, P1, P2, and P3. A Port mismatch event occurs if the logic levels of the Port’s input pins no longer match the software controlled value. This allows Software to be notified if a certain change or pattern occurs on P0, P1, P2, or P3 input pins regardless of the XBRn settings. The PnMASK registers can be used to individually select which of the port pins should be compared against the PnMATCH registers. A Port mismatch event is generated if (Pn & PnMASK) does not equal (PnMATCH & PnMASK), where n is 0, 1, 2 or 3 A Port mismatch event may be used to generate an interrupt or wake the device from a low power mode, such as IDLE or SUSPEND. See the Interrupts and Power Options chapters for more details on interrupt and wake-up sources. SFR Definition 20.4. P0MASK: Port 0 Mask Register Bit 7 6 5 4 3 2 1 0 Name P0MASK[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xF2; SFR Page = 0x00 Bit Name Function 7:0 P0MASK[7:0] Port 0 Mask Value. Selects P0 pins to be compared to the corresponding bits in P0MAT. 0: P0.n pin logic value is ignored and cannot cause a Port Mismatch event. 1: P0.n pin logic value is compared to P0MAT.n. SFR Definition 20.5. P0MAT: Port 0 Match Register Bit 7 6 5 4 3 2 1 0 Name P0MAT[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xF1; SFR Page = 0x00 Bit Name Function 7:0 P0MAT[7:0] Port 0 Match Value. Match comparison value used on Port 0 for bits in P0MAT which are set to 1. 0: P0.n pin logic value is compared with logic LOW. 1: P0.n pin logic value is compared with logic HIGH. Rev. 1.2 187

C8051F50x/F51x SFR Definition 20.6. P1MASK: Port 1 Mask Register Bit 7 6 5 4 3 2 1 0 Name P1MASK[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xF4; SFR Page = 0x00 Bit Name Function 7:0 P1MASK[7:0] Port 1 Mask Value. Selects P1 pins to be compared to the corresponding bits in P1MAT. 0: P1.n pin logic value is ignored and cannot cause a Port Mismatch event. 1: P1.n pin logic value is compared to P1MAT.n. SFR Definition 20.7. P1MAT: Port 1 Match Register Bit 7 6 5 4 3 2 1 0 Name P1MAT[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xF3; SFR Page = 0x00 Bit Name Function 7:0 P1MAT[7:0] Port 1 Match Value. Match comparison value used on Port 1 for bits in P1MAT which are set to 1. 0: P1.n pin logic value is compared with logic LOW. 1: P1.n pin logic value is compared with logic HIGH. 188 Rev. 1.2

C8051F50x/F51x SFR Definition 20.8. P2MASK: Port 2 Mask Register Bit 7 6 5 4 3 2 1 0 Name P2MASK[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xB2; SFR Page = 0x00 Bit Name Function 7:0 P2MASK[7:0] Port 2 Mask Value. Selects P2 pins to be compared to the corresponding bits in P2MAT. 0: P2.n pin logic value is ignored and cannot cause a Port Mismatch event. 1: P2.n pin logic value is compared to P2MAT.n. SFR Definition 20.9. P2MAT: Port 2 Match Register Bit 7 6 5 4 3 2 1 0 Name P2MAT[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xB1; SFR Page = 0x00 Bit Name Function 7:0 P2MAT[7:0] Port 2 Match Value. Match comparison value used on Port 2 for bits in P2MAT which are set to 1. 0: P2.n pin logic value is compared with logic LOW. 1: P2.n pin logic value is compared with logic HIGH. Rev. 1.2 189

C8051F50x/F51x SFR Definition 20.10. P3MASK: Port 3 Mask Register Bit 7 6 5 4 3 2 1 0 Name P3MASK[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xAF; SFR Page = 0x00 Bit Name Function 7:0 P3MASK[7:0] Port 1 Mask Value. Selects P3 pins to be compared to the corresponding bits in P3MAT. 0: P3.n pin logic value is ignored and cannot cause a Port Mismatch event. 1: P3.n pin logic value is compared to P3MAT.n. Note: P3.1–P3.7 are only available on the 48-pin and 40-pin packages SFR Definition 20.11. P3MAT: Port 3 Match Register Bit 7 6 5 4 3 2 1 0 Name P3MAT[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xAE; SFR Page = 0x00 Bit Name Function 7:0 P3MAT[7:0] Port 3 Match Value. Match comparison value used on Port 3 for bits in P3MAT which are set to 1. 0: P3.n pin logic value is compared with logic LOW. 1: P3.n pin logic value is compared with logic HIGH. Note: P3.1–P3.7 are only available on the 48-pin and 40-pin packages 190 Rev. 1.2

C8051F50x/F51x 20.6. Special Function Registers for Accessing and Configuring Port I/O All Port I/O are accessed through corresponding special function registers (SFRs) that are both byte addressable and bit addressable, except for P4 which is only byte addressable. When writing to a Port, the value written to the SFR is latched to maintain the output data value at each pin. When reading, the logic levels of the Port's input pins are returned regardless of the XBRn settings (i.e., even when the pin is assigned to another signal by the Crossbar, the Port register can always read its corresponding Port I/O pin). The exception to this is the execution of the read-modify-write instructions that target a Port Latch reg- ister as the destination. The read-modify-write instructions when operating on a Port SFR are the following: ANL, ORL, XRL, JBC, CPL, INC, DEC, DJNZ and MOV, CLR or SETB, when the destination is an individ- ual bit in a Port SFR. For these instructions, the value of the latch register (not the pin) is read, modified, and written back to the SFR. Ports 0–3 have a corresponding PnSKIP register which allows its individual Port pins to be assigned to dig- ital functions or skipped by the Crossbar. All Port pins used for analog functions, GPIO, or dedicated digital functions such as the EMIF should have their PnSKIP bit set to 1. The Port input mode of the I/O pins is defined using the Port Input Mode registers (PnMDIN). Each Port cell can be configured for analog or digital I/O. This selection is required even for the digital resources selected in the XBRn registers, and is not automatic. The only exception to this is P4, which can only be used for digital I/O. The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMD- OUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is required even for the digital resources selected in the XBRn registers, and is not automatic. The only exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the PnMDOUT settings. SFR Definition 20.12. P0: Port 0 Bit 7 6 5 4 3 2 1 0 Name P0[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0x80; SFR Page = All Pages; Bit-Addressable Bit Name Description Write Read 7:0 P0[7:0] Port 0 Data. 0: Set output latch to logic 0: P0.n Port pin is logic LOW. LOW. Sets the Port latch logic value or reads the Port pin 1: Set output latch to logic 1: P0.n Port pin is logic logic state in Port cells con- HIGH. HIGH. figured for digital I/O. Rev. 1.2 191

C8051F50x/F51x SFR Definition 20.13. P0MDIN: Port 0 Input Mode Bit 7 6 5 4 3 2 1 0 Name P0MDIN[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xF1; SFR Page = 0x0F Bit Name Function 7:0 P0MDIN[7:0] Analog Configuration Bits for P0.7–P0.0 (respectively). Port pins configured for analog mode have their weak pull-up and digital receiver disabled. For analog mode, the pin also needs to be configured for open-drain mode in the P0MDOUT register. 0: Corresponding P0.n pin is configured for analog mode. 1: Corresponding P0.n pin is not configured for analog mode. SFR Definition 20.14. P0MDOUT: Port 0 Output Mode Bit 7 6 5 4 3 2 1 0 Name P0MDOUT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xA4; SFR Page = 0x0F Bit Name Function 7:0 P0MDOUT[7:0] Output Configuration Bits for P0.7–P0.0 (respectively). These bits are ignored if the corresponding bit in register P0MDIN is logic 0. 0: Corresponding P0.n Output is open-drain. 1: Corresponding P0.n Output is push-pull. 192 Rev. 1.2

C8051F50x/F51x SFR Definition 20.15. P0SKIP: Port 0 Skip Bit 7 6 5 4 3 2 1 0 Name P0SKIP[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD4; SFR Page = 0x0F Bit Name Function 7:0 P0SKIP[7:0] Port 0 Crossbar Skip Enable Bits. These bits select Port 0 pins to be skipped by the Crossbar Decoder. Port pins used for analog, special functions or GPIO should be skipped by the Crossbar. 0: Corresponding P0.n pin is not skipped by the Crossbar. 1: Corresponding P0.n pin is skipped by the Crossbar. SFR Definition 20.16. P1: Port 1 Bit 7 6 5 4 3 2 1 0 Name P1[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0x90; SFR Page = All Pages; Bit-Addressable Bit Name Description Write Read 7:0 P1[7:0] Port 1 Data. 0: Set output latch to logic 0: P1.n Port pin is logic LOW. LOW. Sets the Port latch logic value or reads the Port pin 1: Set output latch to logic 1: P1.n Port pin is logic logic state in Port cells con- HIGH. HIGH. figured for digital I/O. Rev. 1.2 193

C8051F50x/F51x SFR Definition 20.17. P1MDIN: Port 1 Input Mode Bit 7 6 5 4 3 2 1 0 Name P1MDIN[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xF2; SFR Page = 0x0F Bit Name Function 7:0 P1MDIN[7:0] Analog Configuration Bits for P1.7–P1.0 (respectively). Port pins configured for analog mode have their weak pull-up and digital receiver disabled. For analog mode, the pin also needs to be configured for open-drain mode in the P1MDOUT register. 0: Corresponding P1.n pin is configured for analog mode. 1: Corresponding P1.n pin is not configured for analog mode. SFR Definition 20.18. P1MDOUT: Port 1 Output Mode Bit 7 6 5 4 3 2 1 0 Name P1MDOUT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xA5; SFR Page = 0x0F Bit Name Function 7:0 P1MDOUT[7:0] Output Configuration Bits for P1.7–P1.0 (respectively). These bits are ignored if the corresponding bit in register P1MDIN is logic 0. 0: Corresponding P1.n Output is open-drain. 1: Corresponding P1.n Output is push-pull. 194 Rev. 1.2

C8051F50x/F51x SFR Definition 20.19. P1SKIP: Port 1 Skip Bit 7 6 5 4 3 2 1 0 Name P1SKIP[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD5; SFR Page = 0x0F Bit Name Function 7:0 P1SKIP[7:0] Port 1 Crossbar Skip Enable Bits. These bits select Port 1 pins to be skipped by the Crossbar Decoder. Port pins used for analog, special functions or GPIO should be skipped by the Crossbar. 0: Corresponding P1.n pin is not skipped by the Crossbar. 1: Corresponding P1.n pin is skipped by the Crossbar. SFR Definition 20.20. P2: Port 2 Bit 7 6 5 4 3 2 1 0 Name P2[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xA0; SFR Page = All Pages; Bit-Addressable Bit Name Description Write Read 7:0 P2[7:0] Port 2Data. 0: Set output latch to logic 0: P2.n Port pin is logic LOW. LOW. Sets the Port latch logic value or reads the Port pin 1: Set output latch to logic 1: P2.n Port pin is logic logic state in Port cells con- HIGH. HIGH. figured for digital I/O. Rev. 1.2 195

C8051F50x/F51x SFR Definition 20.21. P2MDIN: Port 2 Input Mode Bit 7 6 5 4 3 2 1 0 Name P2MDIN[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xF3; SFR Page = 0x0F Bit Name Function 7:0 P2MDIN[7:0] Analog Configuration Bits for P2.7–P2.0 (respectively). Port pins configured for analog mode have their weak pull-up and digital receiver disabled. For analog mode, the pin also needs to be configured for open-drain mode in the P2MDOUT register. 0: Corresponding P2.n pin is configured for analog mode. 1: Corresponding P2.n pin is not configured for analog mode. SFR Definition 20.22. P2MDOUT: Port 2 Output Mode Bit 7 6 5 4 3 2 1 0 Name P2MDOUT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xA6; SFR Page = 0x0F Bit Name Function 7:0 P2MDOUT[7:0] Output Configuration Bits for P2.7–P2.0 (respectively). These bits are ignored if the corresponding bit in register P2MDIN is logic 0. 0: Corresponding P2.n Output is open-drain. 1: Corresponding P2.n Output is push-pull. 196 Rev. 1.2

C8051F50x/F51x SFR Definition 20.23. P2SKIP: Port 2 Skip Bit 7 6 5 4 3 2 1 0 Name P2SKIP[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD6; SFR Page = 0x0F Bit Name Function 7:0 P2SKIP[7:0] Port 2 Crossbar Skip Enable Bits. These bits select Port 2 pins to be skipped by the Crossbar Decoder. Port pins used for analog, special functions or GPIO should be skipped by the Crossbar. 0: Corresponding P2.n pin is not skipped by the Crossbar. 1: Corresponding P2.n pin is skipped by the Crossbar. SFR Definition 20.24. P3: Port 3 Bit 7 6 5 4 3 2 1 0 Name P3[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xB0; SFR Page = All Pages; Bit-Addressable Bit Name Description Write Read 7:0 P3[7:0] Port 3 Data. 0: Set output latch to logic 0: P3.n Port pin is logic LOW. LOW. Sets the Port latch logic value or reads the Port pin 1: Set output latch to logic 1: P3.n Port pin is logic logic state in Port cells con- HIGH. HIGH. figured for digital I/O. Note: Port P3.1–P3.7 are only available on the 48-pin and 40-pin packages. Rev. 1.2 197

C8051F50x/F51x SFR Definition 20.25. P3MDIN: Port 3 Input Mode Bit 7 6 5 4 3 2 1 0 Name P3MDIN[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xF4; SFR Page = 0x0F Bit Name Function 7:0 P3MDIN[7:0] Analog Configuration Bits for P3.7–P3.0 (respectively). Port pins configured for analog mode have their weak pull-up and digital receiver disabled. For analog mode, the pin also needs to be configured for open-drain mode in the P3MDOUT register. 0: Corresponding P3.n pin is configured for analog mode. 1: Corresponding P3.n pin is not configured for analog mode. Note: Port P3.1–P3.7 are only available on the 48-pin and 40-pin packages. SFR Definition 20.26. P3MDOUT: Port 3 Output Mode Bit 7 6 5 4 3 2 1 0 Name P3MDOUT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xAE; SFR Page = 0x0F Bit Name Function 7:0 P3MDOUT[7:0] Output Configuration Bits for P3.7–P3.0 (respectively). These bits are ignored if the corresponding bit in register P3MDIN is logic 0. 0: Corresponding P3.n Output is open-drain. 1: Corresponding P3.n Output is push-pull. Note: Port P3.1–P3.7 are only available on the and 40-pin 48-pin packages. 198 Rev. 1.2

C8051F50x/F51x SFR Definition 20.27. P3SKIP: Port 3Skip Bit 7 6 5 4 3 2 1 0 Name P3SKIP[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD7; SFR Page = 0x0F Bit Name Function 7:0 P3SKIP[7:0] Port 3 Crossbar Skip Enable Bits. These bits select Port 3 pins to be skipped by the Crossbar Decoder. Port pins used for analog, special functions or GPIO should be skipped by the Crossbar. 0: Corresponding P3.n pin is not skipped by the Crossbar. 1: Corresponding P3.n pin is skipped by the Crossbar. Note: Port P3.1–P3.7 are only available on the 48-pin and 40-pin packages. SFR Definition 20.28. P4: Port 4 Bit 7 6 5 4 3 2 1 0 Name P4[7:0] Type R/W Reset 1 1 1 1 1 1 1 1 SFR Address = 0xB5; SFR Page = All Pages Bit Name Description Write Read 7:0 P4[7:0] Port 4 Data. 0: Set output latch to logic 0: P4.n Port pin is logic LOW. LOW. Sets the Port latch logic value or reads the Port pin 1: Set output latch to logic 1: P4.n Port pin is logic logic state in Port cells con- HIGH. HIGH. figured for digital I/O. Note: Port 4.0 is only available on the 48-pin and 40-pin packages. P4.1-P4.7 are only available on the 48-pin packages. Rev. 1.2 199

C8051F50x/F51x SFR Definition 20.29. P4MDOUT: Port 4 Output Mode Bit 7 6 5 4 3 2 1 0 Name P4MDOUT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xAF; SFR Page = 0x0F Bit Name Function 7:0 P4MDOUT[7:0] Output Configuration Bits for P4.7–P4.0 (respectively). 0: Corresponding P4.n Output is open-drain. 1: Corresponding P4.n Output is push-pull. Note: Port 4.0 is only available on the 48-pin and 40-pin packages. P4.1-P4.7 are only available on the 48-pin packages. 200 Rev. 1.2

C8051F50x/F51x 21. Local Interconnect Network (LIN) Important Note: This chapter assumes an understanding of the Local Interconnect Network (LIN) proto- col. For more information about the LIN protocol, including specifications, please refer to the LIN consor- tium (http://www.lin-subbus.org). LIN is an asynchronous, serial communications interface used primarily in automotive networks. The Sili- con Laboratories LIN controller is compliant to the 2.1 Specification, implements a complete hardware LIN interface and includes the following features:  Selectable Master and Slave modes.  Automatic baud rate option in slave mode.  The internal oscillator is accurate to within 0.5% of 24 MHz across the entire temperature range and for VDD voltages greater than or equal to the minimum output of the on-chip voltage regulator, so an external oscillator is not necessary for master mode operation for most systems. Note: The minimum system clock (SYSCLK) required when using the LIN controller is 8 MHz. C8051F500/2/4/6 LIN Controller 8051 MCU Core LIN Data LIN Control LIN0ADR Registers Registers LIN0DAT Indirectly Addressed Registers TX Control State Machine LIN0CF RX Figure 21.1. LIN Block Diagram The LIN controller has four main components:  LIN Access Registers—Provide the interface between the MCU core and the LIN controller.  LIN Data Registers—Where transmitted and received message data bytes are stored.  LIN Control Registers—Control the functionality of the LIN interface.  Control State Machine and Bit Streaming Logic—Contains the hardware that serializes messages and controls the bus timing of the controller. Rev. 1.2 201

C8051F50x/F51x 21.1. Software Interface with the LIN Controller The selection of the mode (Master or Slave) and the automatic baud rate feature are done though the LIN0 Control Mode (LIN0CF) register. The other LIN registers are accessed indirectly through the two SFRs LIN0 Address (LIN0ADR) and LIN0 Data (LIN0DAT). The LIN0ADR register selects which LIN register is targeted by reads/writes of the LIN0DAT register. The full list of indirectly-accessible LIN registers is given in Table 21.4 on page 210. 21.2. LIN Interface Setup and Operation The hardware based LIN controller allows for the implementation of both Master and Slave nodes with minimal firmware overhead and complete control of the interface status while allowing for interrupt and polled mode operation. The first step to use the controller is to define the basic characteristics of the node: Mode—Master or Slave Baud Rate—Either defined manually or using the autobaud feature (slave mode only) Checksum Type—Select between classic or enhanced checksum, both of which are implemented in hard- ware. 21.2.1. Mode Definition Following the LIN specification, the controller implements in hardware both the Slave and Master operating modes. The mode is configured using the MODE bit (LIN0CF.6). 21.2.2. Baud Rate Options: Manual or Autobaud The LIN controller can be selected to have its baud rate calculated manually or automatically. A master node must always have its baud rate set manually, but slave nodes can choose between a manual or auto- matic setup. The configuration is selected using the ABAUD bit (LIN0CF.5). Both the manual and automatic baud rate configurations require additional setup. The following sections explain the different options available and their relation with the baud rate, along with the steps necessary to achieve the required baud rate. 21.2.3. Baud Rate Calculations: Manual Mode The baud rate used by the LIN controller is a function of the System Clock (SYSCLK) and the LIN timing registers according to the following equation: SYSCLK baud_rate = --------------------------------------------------------------------------------------------------------------------- (prescaler+1) 2 ×divider×(multiplier+1) The prescaler, divider and multiplier factors are part of the LIN0DIV and LIN0MUL registers and can assume values in the following range: Table 21.1. Baud Rate Calculation Variable Ranges Factor Range prescaler 0…3 multiplier 0…31 divider 200…511 Important Note: The minimum system clock (SYSCLK) to operate the LIN controller is 8 MHz. 202 Rev. 1.2

C8051F50x/F51x Use the following equations to calculate the values for the variables for the baud-rate equation: 20000 multiplier = -----------------------------–1 baud_rate SYSCLK × 1 prescaler = ln ------------------------------------------------------------------------------------------------ --------–1 (multiplier+1) ×baud_rate ×200 ln2 SYSCLK divider = -------------------------------------------------------------------------------------------------------------------------------------- (2(prescaler+1)× (multiplier+1) × baud_rate) In all of these equations, the results must be rounded down to the nearest integer. The following example shows the steps for calculating the baud rate values for a Master node running at 24 MHz and communicating at 19200 bits/sec. First, calculate the multiplier: 20000 ≅ multiplier = ----------------–1 = 0.0417 0 19200 Next, calculate the prescaler: 24000000 × 1 ≅ prescaler = ln----------------------------------------------------------- --------–1 = 1.644 1 (0+1) ×19200× 200 ln2 Finally, calculate the divider: 24000000 ≅ divider = ----------------------------------------------------------------------- = 312.5 312 2(1+1)× (0+1) ×19200 These values lead to the following baud rate: 24000000 ≅ baud_rate = ---------------------------------------------------------------- 19230.77 2(1+1) ×(0+1) ×312 The following code programs the interface in Master mode, using the Enhanced Checksum and enables the interface to operate at 19230 bits/sec using a 24 MHz system clock. LIN0CF = 0x80; // Activate the interface LIN0CF |= 0x40; // Set the node as a Master LIN0ADR = 0x0D; // Point to the LIN0MUL register // Initialize the register (prescaler, multiplier and bit 8 of divider) LIN0DAT = ( 0x01 << 6 ) + ( 0x00 << 1 ) + ( ( 0x138 & 0x0100 ) >> 8 ); LIN0ADR = 0x0C; // Point to the LIN0DIV register LIN0DAT = (unsigned char)_0x138; // Initialize LIN0DIV LIN0ADR = 0x0B; // Point to the LIN0SIZE register LIN0DAT |= 0x80; // Initialize the checksum as Enhanced LIN0ADR = 0x08; // Point to LIN0CTRL register LIN0DAT = 0x0C; // Reset any error and the interrupt Rev. 1.2 203

C8051F50x/F51x Table 21.2 includes the configuration values required for the typical system clocks and baud rates: Table 21.2. Manual Baud Rate Parameters Examples Baud (bits/sec) 20 K 19.2 K 9.6 K 4.8 K 1 K S(YMSHCzL)K Mult. Pres. Div. Mult. Pres. Div. Mult. Pres. Div. Mult. Pres. Div. Mult. Pres. Div. 25 0 1 312 0 1 325 1 1 325 3 1 325 19 1 312 24.5 0 1 306 0 1 319 1 1 319 3 1 319 19 1 306 24 0 1 300 0 1 312 1 1 312 3 1 312 19 1 300 22.1184 0 1 276 0 1 288 1 1 288 3 1 288 19 1 276 16 0 1 200 0 1 208 1 1 208 3 1 208 19 1 200 12.25 0 0 306 0 0 319 1 0 319 3 0 319 19 0 306 12 0 0 300 0 0 312 1 0 312 3 0 312 19 0 300 11.0592 0 0 276 0 0 288 1 0 288 3 0 288 19 0 276 8 0 0 200 0 0 208 1 0 208 3 0 208 19 0 200 21.2.4. Baud Rate Calculations—Automatic Mode If the LIN controller is configured for slave mode, only the prescaler and divider need to be calculated: SYSCLK × 1 prescaler = ln ------------------------- --------–1 4000000 ln2 SYSCLK divider = ---------------------------------------------------------------------- (prescaler+1)× 2 20000 The following example calculates the values of these variables for a 24 MHz system clock: 24000000 × 1 ≅ prescaler = ln -------------------------- --------–1 = 1.585 1 4000000 ln2 24000000 divider = --------------------------------------------- = 300 (1+1) × 2 20000 Table 21.3 presents some typical values of system clock and baud rate along with their factors. 204 Rev. 1.2

C8051F50x/F51x Table 21.3. Autobaud Parameters Examples System Clock (MHz) Prescaler Divider 25 1 312 24.5 1 306 24 1 300 22.1184 1 276 16 1 200 12.25 0 306 12 0 300 11.0592 0 276 8 0 200 21.3. LIN Master Mode Operation The master node is responsible for the scheduling of messages and sends the header of each frame con- taining the SYNCH BREAK FIELD, SYNCH FIELD, and IDENTIFIER FIELD. The steps to schedule a mes- sage transmission or reception are listed below. 1. Load the 6-bit Identifier into the LIN0ID register. 2. Load the data length into the LIN0SIZE register. Set the value to the number of data bytes or "1111b" if the data length should be decoded from the identifier. Also, set the checksum type, classic or enhanced, in the same LIN0SIZE register. 3. Set the data direction by setting the TXRX bit (LIN0CTRL.5). Set the bit to 1 to perform a master transmit operation, or set the bit to 0 to perform a master receive operation. 4. If performing a master transmit operation, load the data bytes to transmit into the data buffer (LIN0DT1 to LIN0DT8). 5. Set the STREQ bit (LIN0CTRL.0) to start the message transfer. The LIN controller will schedule the message frame and request an interrupt if the message transfer is successfully completed or if an error has occurred. This code segment shows the procedure to schedule a message in a transmission operation: LIN0ADR = 0x08; // Point to LIN0CTRL LIN0DAT |= 0x20; // Select to transmit data LIN0ADR = 0x0E; // Point to LIN0ID LIN0DAT = 0x11; // Load the ID, in this example 0x11 LIN0ADR = 0x0B; // Point to LIN0SIZE LIN0DAT = ( LIN0DAT & 0xF0 ) | 0x08; // Load the size with 8 LIN0ADR = 0x00; // Point to Data buffer first byte for (i=0; i<8; i++) { LIN0DAT = i + 0x41; // Load the buffer with ‘A’, ‘B’, ... LIN0ADR++; // Increment the address to the next buffer } LIN0ADR = 0x08; // Point to LIN0CTRL LIN0DAT = 0x01; // Start Request The application should perform the following steps when an interrupt is requested. Rev. 1.2 205

C8051F50x/F51x 1. Check the DONE bit (LIN0ST.0) and the ERROR bit (LIN0ST.2). 2. If performing a master receive operation and the transfer was successful, read the received data from the data buffer. 3. If the transfer was not successful, check the error register to determine the kind of error. Further error handling has to be done by the application. 4. Set the RSTINT (LIN0CTRL.3) and RSTERR bits (LIN0CTRL.2) to reset the interrupt request and the error flags. 21.4. LIN Slave Mode Operation When the device is configured for slave mode operation, it must wait for a command from a master node. Access from the firmware to the data buffer and ID registers of the LIN controller is only possible when a data request is pending (DTREQ bit (LIN0ST.4) is 1) and also when the LIN bus is not active (ACTIVE bit (LIN0ST.7) is set to 0). The LIN controller in slave mode detects the header of the message frame sent by the LIN master. If slave synchronization is enabled (autobaud), the slave synchronizes its internal bit time to the master bit time. The LIN controller configured for slave mode will generated an interrupt in one of three situations: 1. After the reception of the IDENTIFIER FIELD 2. When an error is detected 3. When the message transfer is completed. The application should perform the following steps when an interrupt is detected: 1. Check the status of the DTREQ bit (LIN0ST.4). This bit is set when the IDENTIFIER FIELD has been received. 2. If DTREQ (LIN0ST.4) is set, read the identifier from LIN0ID and process it. If DTREQ (LIN0ST.4) is not set, continue to step 7. 3. Set the TXRX bit (LIN0CTRL.5) to 1 if the current frame is a transmit operation for the slave and set to 0 if the current frame is a receive operation for the slave. 4. Load the data length into LIN0SIZE. 5. For a slave transmit operation, load the data to transmit into the data buffer. 6. Set the DTACK bit (LIN0CTRL.4). Continue to step 10. 7. If DTREQ (LIN0ST.4) is not set, check the DONE bit (LIN0ST.0). The transmission was successful if the DONE bit is set. 8. If the transmission was successful and the current frame was a receive operation for the slave, load the received data bytes from the data buffer. 9. If the transmission was not successful, check LIN0ERR to determine the nature of the error. Further error handling has to be done by the application. 10.Set the RSTINT (LIN0CTRL.3) and RSTERR bits (LIN0CTRL.2) to reset the interrupt request and the error flags. In addition to these steps, the application should be aware of the following: 1. If the current frame is a transmit operation for the slave, steps 1 through 5 must be completed during the IN-FRAME RESPONSE SPACE. If it is not completed in time, a timeout will be detected by the master. 2. If the current frame is a receive operation for the slave, steps 1 through 5 have to be finished until the reception of the first byte after the IDENTIFIER FIELD. Otherwise, the internal receive buffer of the LIN controller will be overwritten and a timeout error will be detected in the LIN controller. 3. The LIN controller does not directly support LIN Version 1.3 Extended Frames. If the application detects an unknown identifier (e.g. extended identifier), it has to write a 1 to the STOP bit (LIN0CTRL.7) instead 206 Rev. 1.2

C8051F50x/F51x of setting the DTACK (LIN0CTRL.4) bit. At that time, steps 2 through 5 can then be skipped. In this situation, the LIN controller stops the processing of LIN communication until the next SYNC BREAK is received. 4. Changing the configuration of the checksum during a transaction will cause the interface to reset and the transaction to be lost. To prevent this, the checksum should not be configured while a transaction is in progress. The same applies to changes in the LIN interface mode from slave mode to master mode and from master mode to slave mode. 21.5. Sleep Mode and Wake-Up To reduce the system’s power consumption, the LIN Protocol Specification defines a Sleep Mode. The message used to broadcast a Sleep Mode request must be transmitted by the LIN master application in the same way as a normal transmit message. The LIN slave application must decode the Sleep Mode Frame from the Identifier and data bytes. After that, it has to put the LIN slave node into the Sleep Mode by setting the SLEEP bit (LIN0CTRL.6). If the SLEEP bit (LIN0CTRL.6) of the LIN slave application is not set and there is no bus activity for four seconds (specified bus idle timeout), the IDLTOUT bit (LIN0ST.6) is set and an interrupt request is gener- ated. After that the application may assume that the LIN bus is in Sleep Mode and set the SLEEP bit (LIN0CTRL.6). Sending a wake-up signal from the master or any slave node terminates the Sleep Mode of the LIN bus. To send a wake-up signal, the application has to set the WUPREQ bit (LIN0CTRL.1). After successful trans- mission of the wake-up signal, the DONE bit (LIN0ST.0) of the master node is set and an interrupt request is generated. The LIN slave does not generate an interrupt request after successful transmission of the wake-up signal but it generates an interrupt request if the master does not respond to the wake-up signal within 150 milliseconds. In that case, the ERROR bit (LIN0ST.2) and TOUT bit (LIN0ERR.2) are set. The application then has to decide whether or not to transmit another wake-up signal. All LIN nodes that detect a wake-up signal will set the WAKEUP (LIN0ST.1) and DONE bits (LIN0ST.0) and generate an interrupt request. After that, the application has to clear the SLEEP bit (LIN0CTRL.6) in the LIN slave. 21.6. Error Detection and Handling The LIN controller generates an interrupt request and stops the processing of the current frame if it detects an error. The application has to check the type of error by processing LIN0ERR. After that, it has to reset the error register and the ERROR bit (LIN0ST.2) by writing a 1 to the RSTERR bit (LIN0CTRL.2). Starting a new message with the LIN controller selected as master or sending a Wakeup signal with the LIN control- ler selected as a master or slave is possible only if the ERROR bit (LIN0ST.2) is set to 0. Rev. 1.2 207

C8051F50x/F51x 21.7. LIN Registers The following Special Function Registers (SFRs) and indirect registers are available for the LIN controller. 21.7.1. LIN Direct Access SFR Registers Definitions SFR Definition 21.1. LIN0ADR: LIN0 Indirect Address Register Bit 7 6 5 4 3 2 1 0 Name LIN0ADR[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD3; SFR Page = 0x00 Bit Name Function 7:0 LIN0ADR[7:0] LIN Indirect Address Register Bits. This register hold an 8-bit address used to indirectly access the LIN0 core registers. Table 21.4 lists the LIN0 core registers and their indirect addresses. Reads and writes to LIN0DAT will target the register indicated by the LIN0ADR bits. SFR Definition 21.2. LIN0DAT: LIN0 Indirect Data Register Bit 7 6 5 4 3 2 1 0 Name LIN0DAT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD2; SFR Page = 0x00 Bit Name Function 7:0 LIN0DAT[7:0] LIN Indirect Data Register Bits. When this register is read, it will read the contents of the LIN0 core register pointed to by LIN0ADR. When this register is written, it will write the value to the LIN0 core register pointed to by LIN0ADR. 208 Rev. 1.2

C8051F50x/F51x SFR Definition 21.3. LIN0CF: LIN0 Control Mode Register Bit 7 6 5 4 3 2 1 0 Name LINEN MODE ABAUD Type R/W R/W R/W R R R R R Reset 0 1 1 0 0 0 0 0 SFR Address = 0xC9; SFR Page = 0x0F Bit Name Function 7 LINEN LIN Interface Enable Bit. 0: LIN0 is disabled. 1: LIN0 is enabled. 6 MODE LIN Mode Selection Bit. 0: LIN0 operates in slave mode. 1: LIN0 operates in master mode. 5 ABAUD LIN Mode Automatic Baud Rate Selection. This bit only has an effect when the MODE bit is configured for slave mode. 0: Manual baud rate selection is enabled. 1: Automatic baud rate selection is enabled. 4:0 Unused Read = 00000b; Write = Don’t Care Rev. 1.2 209

C8051F50x/F51x 21.7.2. LIN Indirect Access SFR Registers Definitions Table 21.4 lists the 15 indirect registers used to configured and communicate with the LIN controller. Table 21.4. LIN Registers (Indirectly Addressable) Name Address Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 LIN0DT1 0x00 DATA1[7:0] LIN0DT2 0x01 DATA2[7:0] LIN0DT3 0x02 DATA3[7:0] LIN0DT4 0x03 DATA4[7:0] LIN0DT5 0x04 DATA5[7:0] LIN0DT6 0x05 DATA67:0] LIN0DT7 0x06 DATA7[7:0] LIN0DT8 0x07 DATA8[7:0] LIN0CTRL 0x08 STOP(s) SLEEP(s) TXRX DTACK(s) RSTINT RSTERR WUPREQ STREQ(m) LIN0ST 0x09 ACTIVE IDLTOUT ABORT(s) DTREQ(s) LININT ERROR WAKEUP DONE LIN0ERR 0x0A SYNCH(s) PRTY(s) TOUT CHK BITERR LIN0SIZE 0x0B ENHCHK LINSIZE[3:0] LIN0DIV 0x0C DIVLSB[7:0] LIN0MUL 0x0D PRESCL[1:0] LINMUL[4:0] DIV9 LIN0ID 0x0E ID5 ID4 ID3 ID2 ID1 ID0 Note: These registers are used in both master and slave mode. The register bits marked with (m) are accessible only in Master mode while the register bits marked with (s) are accessible only in slave mode. All other registers are accessible in both modes. 210 Rev. 1.2

C8051F50x/F51x LIN Register Definition 21.4. LIN0DTn: LIN0 Data Byte n Bit 7 6 5 4 3 2 1 0 Name DATAn[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 Indirect Address: LIN0DT1 = 0x00, LIN0DT2 = 0x01, LIN0DT3 = 0x02, LIN0DT4 = 0x03, LIN0DT5 = 0x04, LIN0DT6 = 0x05, LIN0DT7 = 0x06, LIN0DT8 = 0x07 Bit Name Function 7:0 DATAn[7:0] LIN Data Byte n. Serial Data Byte that is received or transmitted across the LIN interface. Rev. 1.2 211

C8051F50x/F51x LIN Register Definition 21.5. LIN0CTRL: LIN0 Control Register Bit 7 6 5 4 3 2 1 0 Name STOP SLEEP TXRX DTACK RSTINT RSTERR WUPREQ STREQ Type W R/W R/W R/W W W R/W R/W Reset 0 0 0 0 0 0 0 0 Indirect Address = 0x08 Bit Name Function 7 STOP Stop Communication Processing Bit. (slave mode only) This bit always reads as 0. 0: No effect. 1: Block the processing of LIN communications until the next SYNC BREAK signal. 6 SLEEP Sleep Mode Bit. (slave mode only) 0: Wake the device after receiving a Wakeup interrupt. 1: Put the device into sleep mode after receiving a Sleep Mode frame or a bus idle timeout. 5 TXRX Transmit / Receive Selection Bit. 0: Current frame is a receive operation. 1: Current frame is a transmit operation. 4 DTACK Data Acknowledge Bit. (slave mode only) Set to 1 after handling a data request interrupt to acknowledge the transfer. The bit will automatically be cleared to 0 by the LIN controller. 3 RSTINT Reset Interrupt Bit. This bit always reads as 0. 0: No effect. 1: Reset the LININT bit (LIN0ST.3). 2 RSTERR Reset Error Bit. This bit always reads as 0. 0: No effect. 1: Reset the error bits in LIN0ST and LIN0ERR. 1 WUPREQ Wakeup Request Bit. Set to 1 to terminate sleep mode by sending a wakeup signal. The bit will automati- cally be cleared to 0 by the LIN controller. 0 STREQ Start Request Bit. (master mode only) 1: Start a LIN transmission. This should be set only after loading the identifier, data length and data buffer if necessary. The bit is reset to 0 upon transmission completion or error detection. 212 Rev. 1.2

C8051F50x/F51x LIN Register Definition 21.6. LIN0ST: LIN0 Status Register Bit 7 6 5 4 3 2 1 0 Name ACTIVE IDLTOUT ABORT DTREQ LININT ERROR WAKEUP DONE Type R R R R R R R R Reset 0 0 0 0 0 0 0 0 Indirect Address = 0x09 Bit Name Function 7 ACTIVE LIN Active Indicator Bit. 0: No transmission activity detected on the LIN bus. 1: Transmission activity detected on the LIN bus. 6 IDLT Bus Idle Timeout Bit. (slave mode only) 0: The bus has not been idle for four seconds. 1: No bus activity has been detected for four seconds, but the bus is not yet in Sleep mode. 5 ABORT Aborted Transmission Bit. (slave mode only) 0: The current transmission has not been interrupted or stopped. This bit is reset to 0 after receiving a SYNCH BREAK that does not interrupt a pending transmission. 1: New SYNCH BREAK detected before the end of the last transmission or the STOP bit (LIN0CTRL.7) has been set. 4 DTREQ Data Request Bit. (slave mode only) 0: Data identifier has not been received. 1: Data identifier has been received. 3 LININT Interrupt Request Bit. 0: An interrupt is not pending. This bit is cleared by setting RSTINT (LIN0CTRL.3) 1: There is a pending LIN0 interrupt. 2 ERROR Communication Error Bit. 0: No error has been detected. This bit is cleared by setting RSTERR (LIN0CTRL.2) 1: An error has been detected. 1 WAKEUP Wakeup Bit. 0: A wakeup signal is not being transmitted and has not been received. 1: A wakeup signal is being transmitted or has been received 0 DONE Transmission Complete Bit. 0: A transmission is not in progress or has not been started. This bit is cleared at the start of a transmission. 1: The current transmission is complete. Rev. 1.2 213

C8051F50x/F51x LIN Register Definition 21.7. LIN0ERR: LIN0 Error Register Bit 7 6 5 4 3 2 1 0 Name SYNCH PRTY TOUT CHK BITERR Type R R R R R R R R Reset 0 0 0 0 0 0 0 0 Indirect Address = 0x0A Bit Name Function 7:5 Unused Read = 000b; Write = Don’t Care 4 SYNCH Synchronization Error Bit (slave mode only). 0: No error with the SYNCH FIELD has been detected. 1: Edges of the SYNCH FIELD are outside of the maximum tolerance. 3 PRTY Parity Error Bit (slave mode only). 0: No parity error has been detected. 1: A parity error has been detected. 2 TOUT Timeout Error Bit. 0: A timeout error has not been detected. 1: A timeout error has been detected. This error is detected whenever one of the fol- lowing conditions is met: • The master is expecting data from a slave and the slave does not respond. • The slave is expecting data but no data is transmitted on the bus. • A frame is not finished within the maximum frame length. • The application does not set the DTACK bit (LIN0CTRL.4) or STOP bit (LIN0CTRL.7) until the end of the reception of the first byte after the identifier. 1 CHK Checksum Error Bit. 0: Checksum error has not been detected. 1: Checksum error has been detected. 0 BITERR Bit Transmission Error Bit. 0: No error in transmission has been detected. 1: The bit value monitored during transmission is different than the bit value sent. 214 Rev. 1.2

C8051F50x/F51x LIN Register Definition 21.8. LIN0SIZE: LIN0 Message Size Register Bit 7 6 5 4 3 2 1 0 Name ENHCHK LINSIZE[3:0] Type R/W R R R R/W Reset 0 0 0 0 0 0 0 0 Indirect Address = 0x0B Bit Name Function 7 ENHCHK Checksum Selection Bit. 0: Use the classic, specification 1.3 compliant checksum. Checksum covers the data bytes. 1: Use the enhanced, specification 2.0 compliant checksum. Checksum covers data bytes and protected identifier. 6:4 Unused Read = 000b; Write = Don’t Care 3:0 LINSIZE[3:0] Data Field Size. 0000: 0 data bytes 0001: 1 data byte 0010: 2 data bytes 0011: 3 data bytes 0100: 4 data bytes 0101: 5 data bytes 0110: 6 data bytes 0111: 7 data bytes 1000: 8 data bytes 1001-1110: RESERVED 1111: Use the ID[1:0] bits (LIN0ID[5:4]) to determine the data length. Rev. 1.2 215

C8051F50x/F51x LIN Register Definition 21.9. LIN0DIV: LIN0 Divider Register Bit 7 6 5 4 3 2 1 0 Name DIVLSB[3:0] Type R/W Reset 1 1 1 1 1 1 1 1 Indirect Address = 0x0C Bit Name Function 7:0 DIVLSB LIN Baud Rate Divider Least Significant Bits. The 8 least significant bits for the baud rate divider. The 9th and most significant bit is the DIV9 bit (LIN0MUL.0). The valid range for the divider is 200 to 511. LIN Register Definition 21.10. LIN0MUL: LIN0 Multiplier Register Bit 7 6 5 4 3 2 1 0 Name PRESCL[1:0] LINMUL[4:0] DIV9 Type R/W R/W R/W Reset 1 1 1 1 1 1 1 1 Indirect Address = 0x0D Bit Name Function 7:6 PRESCL[1:0] LIN Baud Rate Prescaler Bits. These bits are the baud rate prescaler bits. 5:1 LINMUL[4:0] LIN Baud Rate Multiplier Bits. These bits are the baud rate multiplier bits. These bits are not used in slave mode. 0 DIV9 LIN Baud Rate Divider Most Significant Bit. The most significant bit of the baud rate divider. The 8 least significant bits are in LIN0DIV. The valid range for the divider is 200 to 511. 216 Rev. 1.2

C8051F50x/F51x LIN Register Definition 21.11. LIN0ID: LIN0 Identifier Register Bit 7 6 5 4 3 2 1 0 Name ID[5:0] Type R R R/W Reset 0 0 0 0 0 0 0 0 Indirect Address = 0x0E Bit Name Function 7:6 Unused Read = 00b; Write = Don’t Care. 5:0 ID[5:0] LIN Identifier Bits. These bits form the data identifier. If the LINSIZE bits (LIN0SIZE[3:0]) are 1111b, bits ID[5:4] are used to determine the data size and are interpreted as follows: 00: 2 bytes 01: 2 bytes 10: 4 bytes 11: 8 bytes Rev. 1.2 217

C8051F50x/F51x 22. Controller Area Network (CAN0) Important Documentation Note: The Bosch CAN Controller is integrated in the C8051F500/2/4/6/8-F510 devices. This section of the data sheet gives a description of the CAN controller as an overview and offers a description of how the Silicon Labs CIP-51 MCU interfaces with the on-chip Bosch CAN controller. In order to use the CAN controller, refer to Bosch’s C_CAN User’s Manual as an accompanying manual to the Silicon Labs’ data sheet. The C8051F500/2/4/6/8-F510 devices feature a Control Area Network (CAN) controller that enables serial communication using the CAN protocol. Silicon Labs CAN facilitates communication on a CAN network in accordance with the Bosch specification 2.0A (basic CAN) and 2.0B (full CAN). The CAN controller con- sists of a CAN Core, Message RAM (separate from the CIP-51 RAM), a message handler state machine, and control registers. Silicon Labs CAN is a protocol controller and does not provide physical layer drivers (i.e., transceivers). Figure 22.1 shows an example typical configuration on a CAN bus. Silicon Labs CAN operates at bit rates of up to 1 Mbit/second, though this can be limited by the physical layer chosen to transmit data on the CAN bus. The CAN processor has 32 Message Objects that can be configured to transmit or receive data. Incoming data, message objects and their identifier masks are stored in the CAN message RAM. All protocol functions for transmission of data and acceptance filtering is performed by the CAN controller and not by the CIP-51 MCU. In this way, minimal CPU bandwidth is needed to use CAN communication. The CIP-51 configures the CAN controller, accesses received data, and passes data for transmission via Special Function Registers (SFRs) in the CIP-51. Silicon Labs MCU CAN Protocol Device CAN Protocol Device CANTX CANRX CAN CAN CAN Transceiver Transceiver Transceiver Isolation/Buffer (Optional) Isolation/Buffer (Optional) Isolation/Buffer (Optional) CAN_H R R CAN_L Figure 22.1. Typical CAN Bus Configuration Rev. 1.2 218

C8051F50x/F51x 22.1. Bosch CAN Controller Operation The CAN Controller featured in the C8051F500/2/4/6/8-F510 devices is a full implementation of Bosch’s full CAN module and fully complies with CAN specification 2.0B. A block diagram of the CAN controller is shown in Figure 22.2. The CAN Core provides shifting (CANTX and CANRX), serial/parallel conversion of messages, and other protocol related tasks such as transmission of data and acceptance filtering. The message RAM stores 32 message objects which can be received or transmitted on a CAN network. The CAN registers and message handler provide an interface for data transfer and notification between the CAN controller and the CIP-51. The function and use of the CAN Controller is detailed in the Bosch CAN User’s Guide. The User’s Guide should be used as a reference to configure and use the CAN controller. This data sheet describes how to access the CAN controller. All of the CAN controller registers are located on SFR Page 0x0C. Before accessing any of the CAN regis- ters, the SFRPAGE register must be set to 0x0C. The CAN Controller is typically initialized using the following steps: 1. Set the SFRPAGE register to the CAN registers page (page 0x0C). 2. Set the INIT and the CCE bits to 1 in CAN0CN. See the CAN User’s Guide for bit definitions. 3. Set timing parameters in the Bit Timing Register and the BRP Extension Register. 4. Initialize each message object or set its MsgVal bit to NOT VALID. 5. Reset the INIT bit to 0. CAN Controller RX TX 8051 MCU Core CAN0CFG Message System Clock Handler CAN Core Message CAN Registers RAM mapped to (32 Objects) SFR space Figure 22.2. CAN Controller Diagram 22.1.1. CAN Controller Timing The CAN controller’s clock (fsys) is derived from the CIP-51 system clock (SYSCLK). The internal oscillator is accurate to within 0.5% of 24 MHz across the entire temperature range and for VDD voltages greater than or equal to the minimum output of the on-chip voltage regulator, and so an external oscillator is not required for CAN communication for most systems. Refer to Section “4.10.4 Oscillator Tolerance Range” in the Bosch CAN User’s Guide for further information regarding this topic. 219 Rev. 1.2

C8051F50x/F51x The CAN controller clock must be less than or equal to 25 MHz. If the CIP-51 system clock is above 25 MHz, the divider in the CAN0CFG register must be set to divide the CAN controller clock down to an appropriate speed. 22.1.2. CAN Register Access The CAN controller clock divider selected in the CAN0CFG SFR affects how the CAN registers can be accessed. If the divider is set to 1, then a CAN SFR can immediately be read after it is written. If the divider is set to a value other than 1, then a read of a CAN SFR that has just been written must be delayed by a certain number of cycles. This delay can be performed using a NOP or some other instruction that does not attempt to read the register. This access limitation applies to read and read-modify-write instructions that occur immediately after a write. The full list of affected instructions is ANL, ORL, MOV, XCH, and XRL. For example, with the CAN0CFG divider set to 1, the CAN0CN SFR can be accessed as follows: MOV CAN0CN, #041 ; Enable access to Bit Timing Register MOV R7, CAN0CN ; Copy CAN0CN to R7 With the CAN0CFG divider set to /2, the same example code requires an additional NOP: MOV CAN0CN, #041 ; Enable access to Bit Timing Register NOP ; Wait for write to complete MOV R7, CAN0CN ; Copy CAN0CN to R7 The number of delay cycles required is dependent on the divider setting. With a divider of 2, the read must wait for 1 system clock cycle. With a divider of 4, the read must wait 3 system clock cycles, and with the divider set to 8, the read must wait 7 system clock cycles. The delay only needs to be applied when read- ing the same register that was written. The application can write and read other CAN SFRs without any delay. 22.1.3. Example Timing Calculation for 1 Mbit/Sec Communication This example shows how to configure the CAN controller timing parameters for a 1 Mbit/Sec bit rate. Table 18.1 shows timing-related system parameters needed for the calculation. Table 22.1. Background System Information Parameter Value Description CIP-51 system clock (SYSCLK) 24 MHz Internal Oscillator Max CAN controller clock (fsys) 24 MHz CAN0CFG divider set to 1 CAN clock period (tsys) 41.667 ns Derived from 1/fsys CAN time quantum (tq) 41.667 ns Derived from tsys x BRP1,2 CAN bus length 10 m 5 ns/m signal delay between CAN nodes Propogation delay time3 400 ns 2 x (transceiver loop delay + bus line delay) Notes: 1. The CAN time quantum is the smallest unit of time recognized by the CAN controller. Bit timing parameters are specified in integer multiples of the time quantum. 2. The Baud Rate Prescaler (BRP) is defined as the value of the BRP Extension Register plus 1. The BRP extension register has a reset value of 0x0000. The BRP has a reset value of 1. 3. Based on an ISO-11898 compliant transceiver. CAN does not specify a physical layer. Each bit transmitted on a CAN network has 4 segments (Sync_Seg, Prop_Seg, Phase_Seg1, and Phase_Seg2), as shown in Figure 18.3. The sum of these segments determines the CAN bit time (1/bit rate). In this example, the desired bit rate is 1 Mbit/sec; therefore, the desired bit time is 1000 ns. Rev. 1.2 220

C8051F50x/F51x CAN Bit Time (4 to 25 t ) q Sync_Seg Prop_Seg Phase_Seg1 Phase_Seg2 1t 1 to 8 t 1 to 8 t 1 to 8 t q q q q 1t q Sample Point Figure 22.3. Four segments of a CAN Bit The length of the 4 bit segments must be adjusted so that their sum is as close as possible to the desired bit time. Since each segment must be an integer multiple of the time quantum (tq), the closest achievable bit time is 24 tq (1000.008 ns), yielding a bit rate of 0.999992 Mbit/sec. The Sync_Seg is a constant 1 tq. The Prop_Seg must be greater than or equal to the propagation delay of 400 ns and so the choice is 10 tq (416.67 ns). The remaining time quanta (13 tq) in the bit time are divided between Phase_Seg1 and Phase_Seg2 as shown in. Based on this equation, Phase_Seg1 = 6 tq and Phase_Seg2 = 7 tq. Phase_Seg1 + Phase_Seg2 = Bit_Time – (Synch_Seg + Prop_Seg) 1. If Phase_Seg1 + Phase_Seg2 is even, then Phase_Seg2 = Phase_Seg1. If the sum is odd, Phase_Seg2 = Phase_Seg1 + 1. 2. Phase_Seg2 should be at least 2 tq. Equation 22.1. Assigning the Phase Segments The Synchronization Jump Width (SJW) timing parameter is defined by. It is used for determining the value written to the Bit Timing Register and for determining the required oscillator tolerance. Since we are using a quartz crystal as the system clock source, an oscillator tolerance calculation is not needed. SJW = minimum (4, Phase_Seg1) Equation 22.2. Synchronization Jump Width (SJW) The value written to the Bit Timing Register can be calculated using Equation 18.3. The BRP Extension register is left at its reset value of 0x0000. BRPE = BRP – 1 = BRP Extension Register = 0x0000 SJWp = SJW – 1 = minimum (4, 6) – 1 = 3 TSEG1 = Prop_Seg + Phase_Seg1 - 1 = 10 + 6 – 1 = 15 TSEG2 = Phase_Seg2 – 1 = 6 Bit Timing Register = (TSEG2x0x1000) + (TSEG1x0x0100) Bit Timing Register = (TSEG2 x 0x1000) + (TSEG1 x 0x0100) + (SJWp x 0x0040) + BRPE = 0x6FC0 Equation 22.3. Calculating the Bit Timing Register Value 221 Rev. 1.2

C8051F50x/F51x 22.2. CAN Registers CAN registers are classified as follows: 1. CAN Controller Protocol Registers: CAN control, interrupt, error control, bus status, test modes. 2. Message Object Interface Registers: Used to configure 32 Message Objects, send and receive data to and from Message Objects. The CIP-51 MCU accesses the CAN message RAM via the Message Object Interface Registers. Upon writing a message object number to an IF1 or IF2 Command Request Register, the contents of the associated Interface Registers (IF1 or IF2) will be transferred to or from the message object in CAN RAM. 3. Message Handler Registers: These read only registers are used to provide information to the CIP-51 MCU about the message objects (MSGVLD flags, Transmission Request Pending, New Data Flags) and Interrupts Pending (which Message Objects have caused an interrupt or status interrupt condition). For the registers other than CAN0CFG, refer to the Bosch CAN User’s Guide for information on the func- tion and use of the CAN Control Protocol Registers. 22.2.1. CAN Controller Protocol Registers The CAN Control Protocol Registers are used to configure the CAN controller, process interrupts, monitor bus status, and place the controller in test modes. The registers are: CAN Control Register (CAN0CN), CAN Clock Configuration (CAN0CFG), CAN Status Register (CAN0STA), CAN Test Register (CAN0TST), Error Counter Register, Bit Timing Register, and the Baud Rate Prescaler (BRP) Extension Register. 22.2.2. Message Object Interface Registers There are two sets of Message Object Interface Registers used to configure the 32 Message Objects that transmit and receive data to and from the CAN bus. Message objects can be configured for transmit or receive, and are assigned arbitration message identifiers for acceptance filtering by all CAN nodes. Message Objects are stored in Message RAM, and are accessed and configured using the Message Object Interface Registers. 22.2.3. Message Handler Registers The Message Handler Registers are read only registers. The message handler registers provide interrupt, error, transmit/receive requests, and new data information. Rev. 1.2 222

C8051F50x/F51x 22.2.4. CAN Register Assignment The standard Bosch CAN registers are mapped to SFR space as shown below and their full definitions are available in the CAN User’s Guide. The name shown in the Name column matches what is provided in the CAN User's Guide. One additional SFR which is not a standard Bosch CAN register, CAN0CFG, is pro- vided to configure the CAN clock. All CAN registers are located on SFR Page 0x0C. Table 22.2. Standard CAN Registers and Reset Values CAN Name SFR Name SFR SFR Name SFR 16-bit Reset Addr. (High) Addr. (Low) Addr. SFR Value 0x00 CAN Control Register — — CAN0CN 0xC0 — 0x01 0x02 Status Register — — CAN0STAT 0x94 — 0x00 0x04 Error Counter1 CAN0ERRH 0x97 CAN0ERRL 0x96 CAN0ERR 0x0000 0x06 Bit Timing Register2 CAN0BTH 0x9B CAN0BTL 0x9A CAN0BT 0x2301 0x08 Interrupt Register1 CAN0IIDH 0x9D CAN0IIDL 0x9C CAN0IID 0x0000 0x0A Test Register — — CAN0TST 0x9E — 0x003,4 0x0C BRP Extension Register2 — — CAN0BRPE 0xA1 — 0x00 0x10 IF1 Command Request CAN0IF1CRH 0xBF CAN0IF1CRL 0xBE CAN0IF1CR 0x0001 0x12 IF1 Command Mask CAN0IF1CMH 0xC3 CAN0IF1CML 0xC2 CAN0IF1CM 0x0000 0x14 IF1 Mask 1 CAN0IF1M1H 0xC5 CAN0IF1M1L 0xC4 CAN0IF1M1 0xFFFF 0x16 IF1 Mask 2 CAN0IF1M2H 0xC7 CAN0IF1M2L 0xC6 CAN0IF1M2 0xFFFF 0x18 IF1 Arbitration 1 CAN0IF1A1H 0xCB CAN0IF1A1L 0xCA CAN0IF1A1 0x0000 0x1A IF1 Arbitration 2 CAN0IF1A2H 0xCD CAN0IF1A2L 0xCC CAN0IF1A2 0x0000 0x1C IF1 Message Control CAN0IF1MCH 0xD3 CAN0IF1MCL 0xD2 CAN0IF1MC 0x0000 0x1E IF1 Data A 1 CAN0IF1DA1H 0xD5 CAN0IF1DA1L 0xD4 CAN0IF1DA1 0x0000 0x20 IF1 Data A 2 CAN0IF1DA2H 0xD7 CAN0IF1DA2L 0xD6 CAN0IF1DA2 0x0000 0x22 IF1 Data B 1 CAN0IF1DB1H 0xDB CAN0IF1DB1L 0xDA CAN0IF1DB1 0x0000 0x24 IF1 Data B 2 CAN0IF1DB2H 0xDD CAN0IF1DB2L 0xDC CAN0IF1DB2 0x0000 0x40 IF2 Command Request CAN0IF2CRH 0xDF CAN0IF2CRL 0xDE CAN0IF2CR 0x0001 0x42 IF2 Command Mask CAN0IF2CMH 0xE3 CAN0IF2CML 0xE2 CAN0IF2CM 0x0000 0x44 IF2 Mask 1 CAN0IF2M1H 0xEB CAN0IF2M1L 0xEA CAN0IF2M1 0xFFFF 0x46 IF2 Mask 2 CAN0IF2M2H 0xED CAN0IF2M2L 0xEC CAN0IF2M2 0xFFFF 0x48 IF2 Arbitration 1 CAN0IF2A1H 0xEF CAN0IF2A1L 0xEE CAN0IF2A1 0x0000 0x4A IF2 Arbitration 2 CAN0IF2A2H 0xF3 CAN0IF2A2L 0xF2 CAN0IF2A2 0x0000 0x4C IF2 Message Control CAN0IF2MCH 0xCF CAN0IF2MCL 0xCE CAN0IF2MC 0x0000 0x4E IF2 Data A 1 CAN0IF2DA1H 0xF7 CAN0IF2DA1L 0xF6 CAN0IF2DA1 0x0000 Notes: 1. Read-only register. 2. Write-enabled by CCE. 3. The reset value of CAN0TST could also be r0000000b, where r signifies the value of the CAN RX pin. 4. Write-enabled by Test. 223 Rev. 1.2

C8051F50x/F51x Table 22.2. Standard CAN Registers and Reset Values(Continued) CAN Name SFR Name SFR SFR Name SFR 16-bit Reset Addr. (High) Addr. (Low) Addr. SFR Value 0x50 IF2 Data A 2 CAN0IF2DA2H 0xFB CAN0IF2DA2L 0xFA CAN0IF2DA2 0x0000 0x52 IF2 Data B 1 CAN0IF2DB1H 0xFD CAN0IF2DB1L 0xFC CAN0IF2DB1 0x0000 0x54 IF2 Data B 2 CAN0IF2DB2H 0xFF CAN0IF2DB2L 0xFE CAN0IF2DB2 0x0000 0x80 Transmission Request 11 CAN0TR1H 0xA3 CAN0TR1L 0xA2 CAN0TR1 0x0000 0x82 Transmission Request 21 CAN0TR2H 0xA5 CAN0TR2L 0xA4 CAN0TR2 0x0000 0x90 New Data 11 CAN0ND1H 0xAB CAN0ND1L 0xAA CAN0ND1 0x0000 0x92 New Data 21 CAN0ND2H 0xAD CAN0ND2L 0xAC CAN0ND2 0x0000 0xA0 Interrupt Pending 11 CAN0IP1H 0xAF CAN0IP1L 0xAE CAN0IP1 0x0000 0xA2 Interrupt Pending 2 1 CAN0IP2H 0xB3 CAN0IP2L 0xB2 CAN0IP2 0x0000 0xB0 Message Valid 11 CAN0MV1H 0xBB CAN0MV1L 0xBA CAN0MV1 0x0000 0xB2 Message Valid 21 CAN0MV2H 0xBD CAN0MV2L 0xBC CAN0MV2 0x0000 Notes: 1. Read-only register. 2. Write-enabled by CCE. 3. The reset value of CAN0TST could also be r0000000b, where r signifies the value of the CAN RX pin. 4. Write-enabled by Test. Rev. 1.2 224

C8051F50x/F51x SFR Definition 22.1. CAN0CFG: CAN Clock Configuration Bit 7 6 5 4 3 2 1 0 Name Unused Unused Unused Unused Unused Unused SYSDIV[1:0] Type R R R R R R R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x92; SFR Page = 0x0C Bit Name Function 7:2 Unused Read = 000000b; Write = Don’t Care. 1:0 SYSDIV[1:0] CAN System Clock Divider Bits. The CAN controller clock is derived from the CIP-51 system clock. The CAN control- ler clock must be less than or equal to 25 MHz. 00: CAN controller clock = System Clock/1. 01: CAN controller clock = System Clock/2. 10: CAN controller clock = System Clock/4. 11: CAN controller clock = System Clock/8. 225 Rev. 1.2

C8051F50x/F51x 23. SMBus The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to the interface by the system controller are byte oriented with the SMBus interface autonomously controlling the serial transfer of the data. Data can be transferred at up to 1/20th of the system clock as a master or slave (this can be faster than allowed by the SMBus specification, depending on the system clock used). A method of extending the clock-low duration is available to accommodate devices with different speed capabilities on the same bus. The SMBus interface may operate as a master and/or slave, and may function on a bus with multiple mas- ters. The SMBus provides control of SDA (serial data), SCL (serial clock) generation and synchronization, arbitration logic, and START/STOP control and generation. A block diagram of the SMBus peripheral and the associated SFRs is shown in Figure 23.1. SMB0CN SMB0CF MT SSAAAS E I BESSSS AX T TCRC I NN UXMMMM SMAOKBK SHS T BBBB TO R L M YHT FCC ED QO B OOT SS RE S L EE 1 0 T D 00 T0 Overflow 01 T1 Overflow 10 TMR2H Overflow 11 TMR2L Overflow SCL SMBUS CONTROL LOGIC FILTER Interrupt Arbitration Request SCL Synchronization SCL Generation (Master Mode) SCL N C SDA Control Control R IRQ Generation O S Data Path SDA S Port I/O Control Control B A R SMB0DAT SDA 7 6 5 4 3 2 1 0 FILTER N Figure 23.1. SMBus Block Diagram Rev. 1.2 226

C8051F50x/F51x 23.1. Supporting Documents It is assumed the reader is familiar with or has access to the following supporting documents: 1. The I2C-Bus and How to Use It (including specifications), Philips Semiconductor. 2. The I2C-Bus Specification—Version 2.0, Philips Semiconductor. 3. System Management Bus Specification—Version 1.1, SBS Implementers Forum. 23.2. SMBus Configuration Figure 23.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage between 3.0 V and 5.0 V; different devices on the bus may operate at different voltage levels. The bi-direc- tional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage through a pullup resistor or similar circuit. Every device connected to the bus must have an open-drain or open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise and fall times on the bus not exceed 300 ns and 1000 ns, respectively. VIO = 5 V VIO = 3 V VIO = 5 V VIO = 3 V Master Slave Slave Device Device 1 Device 2 SDA SCL Figure 23.2. Typical SMBus Configuration 23.3. SMBus Operation Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ). The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme is employed with a single master always winning the arbitration. It is not necessary to specify one device as the Master in a system; any device who transmits a START and a slave address becomes the master for the duration of that transfer. A typical SMBus transaction consists of a START condition followed by an address byte (Bits7–1: 7-bit slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Bytes that are received (by a master or slave) are acknowledged (ACK) with a low SDA during a high SCL (see Figure 23.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowl- edge), which is a high SDA during a high SCL. The direction bit (R/W) occupies the least-significant bit position of the address byte. The direction bit is set to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation. 227 Rev. 1.2

C8051F50x/F51x All transactions are initiated by a master, with one or more addressed slave devices as the target. The master generates the START condition and then transmits the slave address and direction bit. If the trans- action is a WRITE operation from the master to the slave, the master transmits the data a byte at a time waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master generates a STOP condition to terminate the transaction and free the bus. Figure 23.3 illustrates a typical SMBus transaction. SCL SDA SLA6 SLA5-0 R/W D7 D6-0 START Slave Address + R/W ACK Data Byte NACK STOP Figure 23.3. SMBus Transaction 23.3.1. Transmitter vs. Receiver On the SMBus communications interface, a device is the “transmitter” when it is sending an address or data byte to another device on the bus. A device is a “receiver” when an address or data byte is being sent to it from another device on the bus. The transmitter controls the SDA line during the address or data byte. After each byte of address or data information is sent by the transmitter, the receiver sends an ACK or NACK bit during the ACK phase of the transfer, during which time the receiver controls the SDA line. 23.3.2. Arbitration A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL and SDA lines remain high for a specified time (see Section “23.3.5. SCL High (SMBus Free) Timeout” on page 229). In the event that two or more devices attempt to begin a transfer at the same time, an arbitra- tion scheme is employed to force one master to give up the bus. The master devices continue transmitting until one attempts a HIGH while the other transmits a LOW. Since the bus is open-drain, the bus will be pulled LOW. The master attempting the HIGH will detect a LOW SDA and lose the arbitration. The winning master continues its transmission without interruption; the losing master becomes a slave and receives the rest of the transfer if addressed. This arbitration scheme is non-destructive: one device always wins, and no data is lost. 23.3.3. Clock Low Extension SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line LOW to extend the clock low period, effectively decreasing the serial clock frequency. 23.3.4. SCL Low Timeout If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore, the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than 25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communi- cation no later than 10 ms after detecting the timeout condition. When the SMBTOE bit in SMB0CF is set, Timer 3 is used to detect SCL low timeouts. Timer 3 is forced to reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to Rev. 1.2 228

C8051F50x/F51x overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset (disable and re-enable) the SMBus in the event of an SCL low timeout. 23.3.5. SCL High (SMBus Free) Timeout The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and SDA remain high for more than 10 SMBus clock source periods (as defined by the timer configured for the SMBus clock source). If the SMBus is waiting to generate a Master START, the START will be generated following this timeout. Note that a clock source is required for free timeout detection, even in a slave-only implementation. 23.4. Using the SMBus The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting con- trol for serial transfers; higher level protocol is determined by user software. The SMBus interface provides the following application-independent features:  Byte-wise serial data transfers  Clock signal generation on SCL (Master Mode only) and SDA data synchronization  Timeout/bus error recognition, as defined by the SMB0CF configuration register  START/STOP timing, detection, and generation  Bus arbitration  Interrupt generation  Status information SMBus interrupts are generated for each data byte or slave address that is transferred. The point at which the interrupt is generated depends on whether the hardware is acting as a data transmitter or receiver. When a transmitter (i.e. sending address/data, receiving an ACK), this interrupt is generated after the ACK cycle so that software may read the received ACK value; when receiving data (i.e. receiving address/data, sending an ACK), this interrupt is generated before the ACK cycle so that software may define the outgo- ing ACK value. See Section 23.5 for more details on transmission sequences. Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section 23.4.2; Table 23.4 provides a quick SMB0CN decoding reference. 23.4.1. SMBus Configuration Register The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes, select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however, the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of the current transfer). 229 Rev. 1.2

C8051F50x/F51x Table 23.1. SMBus Clock Source Selection SMBCS1 SMBCS0 SMBus Clock Source 0 0 Timer 0 Overflow 0 1 Timer 1 Overflow 1 0 Timer 2 High Byte Overflow 1 1 Timer 2 Low Byte Overflow The SMBCS1–0 bits select the SMBus clock source, which is used only when operating as a master or when the Free Timeout detection is enabled. When operating as a master, overflows from the selected source determine the absolute minimum SCL low and high times as defined in Equation 23.1. Note that the selected clock source may be shared by other peripherals so long as the timer is left running at all times. For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer configuration is covered in Section “26. Timers” on page 265. 1 T = T = ------------------------------------------------- HighMin LowMin f ClockSourceOverflow Equation 23.1. Minimum SCL High and Low Times The selected clock source should be configured to establish the minimum SCL High and Low times as per Equation 23.1. When the interface is operating as a master (and SCL is not driven or extended by any other devices on the bus), the typical SMBus bit rate is approximated by Equation 23.2. f ClockSourceOverflow BitRate = ------------------------------------------------- 3 Equation 23.2. Typical SMBus Bit Rate Figure 23.4 shows the typical SCL generation described by Equation 23.2. Notice that T is typically HIGH twice as large as T . The actual SCL output may vary due to other devices on the bus (SCL may be LOW extended low by slower slave devices, or driven low by contending master devices). The bit rate when operating as a master will never exceed the limits defined by equation Equation 23.1. Timer Source Overflows SCL T T SCL High Timeout Low High Figure 23.4. Typical SMBus SCL Generation Rev. 1.2 230

C8051F50x/F51x Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA setup time defines the absolute minimum time that SDA is stable before SCL transitions from low-to-high. The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 23.2 shows the min- imum setup and hold times for the two EXTHOLD settings. Setup and hold time extensions are typically necessary when SYSCLK is above 10 MHz. Table 23.2. Minimum SDA Setup and Hold Times EXTHOLD Minimum SDA Setup Time Minimum SDA Hold Time 0 T – 4 system clocks 3 system clocks low or 1 system clock + s/w delay* 1 11 system clocks 12 system clocks *Note:Setup Time for ACK bit transmissions and the MSB of all data transfers. When using software acknowledgement, the s/w delay occurs between the time SMB0DAT or ACK is written and when SI is cleared. Note that if SI is cleared in the same write that defines the outgoing ACK value, s/w delay is zero. With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low timeouts (see Section “23.3.4. SCL Low Timeout” on page 228). The SMBus interface will force Timer 3 to reload while SCL is high, and allow Timer 3 to count when SCL is low. The Timer 3 interrupt service routine should be used to reset SMBus communication by disabling and re-enabling the SMBus. SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see Figure 23.4). 231 Rev. 1.2

C8051F50x/F51x SFR Definition 23.1. SMB0CF: SMBus Clock/Configuration Bit 7 6 5 4 3 2 1 0 Name ENSMB INH BUSY EXTHOLD SMBTOE SMBFTE SMBCS[1:0] Type R/W R/W R R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xC1; SFR Page = 0x00 Bit Name Function 7 ENSMB SMBus Enable. This bit enables the SMBus interface when set to 1. When enabled, the interface constantly monitors the SDA and SCL pins. 6 INH SMBus Slave Inhibit. When this bit is set to logic 1, the SMBus does not generate an interrupt when slave events occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are not affected. 5 BUSY SMBus Busy Indicator. This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to logic 0 when a STOP or free-timeout is sensed. 4 EXTHOLD SMBus Setup and Hold Time Extension Enable. This bit controls the SDA setup and hold times according to Table 23.2. 0: SDA Extended Setup and Hold Times disabled. 1: SDA Extended Setup and Hold Times enabled. 3 SMBTOE SMBus SCL Timeout Detection Enable. This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to reload while SCL is high and allows Timer 3 to count when SCL goes low. If Timer 3 is configured to Split Mode, only the High Byte of the timer is held in reload while SCL is high. Timer 3 should be programmed to generate interrupts at 25 ms, and the Timer 3 interrupt service routine should reset SMBus communication. 2 SMBFTE SMBus Free Timeout Detection Enable. When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain high for more than 10 SMBus clock source periods. 1:0 SMBCS[1:0] SMBus Clock Source Selection. These two bits select the SMBus clock source, which is used to generate the SMBus bit rate. The selected device should be configured according to Equation 23.1. 00: Timer 0 Overflow 01: Timer 1 Overflow 10:Timer 2 High Byte Overflow 11: Timer 2 Low Byte Overflow Rev. 1.2 232

C8051F50x/F51x 23.4.2. SMB0CN Control Register SMB0CN is used to control the interface and to provide status information (see SFR Definition 23.2). The higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to jump to service routines. MASTER indicates whether a device is the master or slave during the current transfer. TXMODE indicates whether the device is transmitting or receiving data for the current byte. STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus interrupt. STA and STO are also used to generate START and STOP conditions when operating as a mas- ter. Writing a 1 to STA will cause the SMBus interface to enter Master Mode and generate a START when the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a 1 to STO while in Master Mode will cause the interface to generate a STOP and end the current transfer after the next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be generated. As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit indicates the value received during the last ACK cycle. ACKRQ is set each time a byte is received, indicat- ing that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit; however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further slave events will be ignored until the next START is detected. The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condi- tion. ARBLOST is cleared by hardware each time SI is cleared. The SI bit (SMBus Interrupt Flag) is set at the beginning and end of each transfer, after each byte frame, or when an arbitration is lost; see Table 23.3 for more details. Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and the bus is stalled until software clears SI. 233 Rev. 1.2

C8051F50x/F51x SFR Definition 23.2. SMB0CN: SMBus Control Bit 7 6 5 4 3 2 1 0 Name MASTER TXMODE STA STO ACKRQ ARBLOST ACK SI Type R R R/W R/W R R R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xC0; Bit-Addressable; SFR Page =0x00 Bit Name Description Read Write 7 MASTER SMBus Master/Slave 0: SMBus operating in N/A Indicator. This read-only bit slave mode. indicates when the SMBus is 1: SMBus operating in operating as a master. master mode. 6 TXMODE SMBus Transmit Mode 0: SMBus in Receiver N/A Indicator. This read-only bit Mode. indicates when the SMBus is 1: SMBus in Transmitter operating as a transmitter. Mode. 5 STA SMBus Start Flag. 0: No Start or repeated 0: No Start generated. Start detected. 1: When Configured as a 1: Start or repeated Start Master, initiates a START detected. or repeated START. 4 STO SMBus Stop Flag. 0: No Stop condition 0: No STOP condition is detected. transmitted. 1: Stop condition detected 1: When configured as a (if in Slave Mode) or pend- Master, causes a STOP ing (if in Master Mode). condition to be transmit- ted after the next ACK cycle. Cleared by Hardware. 3 ACKRQ SMBus Acknowledge 0: No Ack requested N/A Request. 1: ACK requested 2 ARBLOST SMBus Arbitration Lost 0: No arbitration error. N/A Indicator. 1: Arbitration Lost 1 ACK SMBus Acknowledge. 0: NACK received. 0: Send NACK 1: ACK received. 1: Send ACK 0 SI SMBus Interrupt Flag. 0: No interrupt pending 0: Clear interrupt, and initi- This bit is set by hardware 1: Interrupt Pending ate next state machine under the conditions listed in event. Table 15.3. SI must be cleared 1: Force interrupt. by software. While SI is set, SCL is held low and the SMBus is stalled. Rev. 1.2 234

C8051F50x/F51x Table 23.3. Sources for Hardware Changes to SMB0CN Bit Set by Hardware When: Cleared by Hardware When: MASTER  A START is generated.  A STOP is generated.  Arbitration is lost. TXMODE  START is generated.  A START is detected.  SMB0DAT is written before the start of an  Arbitration is lost. SMBus frame.  SMB0DAT is not written before the start of an SMBus frame. STA  A START followed by an address byte is  Must be cleared by software. received. STO  A STOP is detected while addressed as a  A pending STOP is generated. slave.  Arbitration is lost due to a detected STOP. ACKRQ  A byte has been received and an ACK  After each ACK cycle. response value is needed. ARBLOST  A repeated START is detected as a  Each time SI is cleared. MASTER when STA is low (unwanted repeated START).  SCL is sensed low while attempting to generate a STOP or repeated START condition.  SDA is sensed low while transmitting a 1 (excluding ACK bits). ACK  The incoming ACK value is low  The incoming ACK value is high (ACKNOWLEDGE). (NOT ACKNOWLEDGE). SI  A START has been generated.  Must be cleared by software.  Lost arbitration.  A byte has been transmitted and an ACK/NACK received.  A byte has been received.  A START or repeated START followed by a slave address + R/W has been received.  A STOP has been received. 235 Rev. 1.2

C8051F50x/F51x 23.4.3. Data Register The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been received. Software may safely read or write to the data register when the SI flag is set. Software should not attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0, as the interface may be in the process of shifting a byte of data into or out of the register. Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbi- tration, the transition from master transmitter to slave receiver is made with the correct data or address in SMB0DAT. SFR Definition 23.3. SMB0DAT: SMBus Data Bit 7 6 5 4 3 2 1 0 Name SMB0DAT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xC2; SMB0DAT = 0x00 Bit Name Function 7:0 SMB0DAT[7:0] SMBus Data. The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial interface or a byte that has just been received on the SMBus serial interface. The CPU can read from or write to this register whenever the SI serial interrupt flag (SMB0CN.0) is set to logic 1. The serial data in the register remains stable as long as the SI flag is set. When the SI flag is not set, the system may be in the process of shifting data in/out and the CPU should not attempt to access this register. 23.5. SMBus Transfer Modes The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end of all SMBus byte frames. As a receiver, the interrupt for an ACK occurs before the ACK. As a transmitter, interrupts occur after the ACK. Rev. 1.2 236

C8051F50x/F51x 23.5.1. Write Sequence (Master) During a write sequence, an SMBus master writes data to a slave device. The master in this transfer will be a transmitter during the address byte, and a transmitter during all data bytes. The SMBus interface gener- ates the START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then trans- mits one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by the slave. The transfer is ended when the STO bit is set and a STOP is generated. Note that the interface will switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt. Figure 23.5 shows a typical master write sequence. Two transmit data bytes are shown, though any num- ber of bytes may be transmitted. Notice that all of the ‘data byte transferred’ interrupts occur after the ACK cycle in this mode. S SLA W A Data Byte A Data Byte A P Interrupts S = START Received by SMBus P = STOP Interface A = ACK Transmitted by W = WRITE SMBus Interface SLA = Slave Address Figure 23.5. Typical Master Write Sequence 237 Rev. 1.2

C8051F50x/F51x 23.5.2. Read Sequence (Master) During a read sequence, an SMBus master reads data from a slave device. The master in this transfer will be a transmitter during the address byte, and a receiver during all data bytes. The SMBus interface gener- ates the START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then received from the slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial data. An interrupt is generated after each received byte. Software must write the ACK bit at that time to ACK or NACK the received byte. Writing a 1 to the ACK bit generates an ACK; writing a 0 generates a NACK. Software should write a 0 to the ACK bit for the last data transfer, to transmit a NACK. The interface exits Master Receiver Mode after the STO bit is set and a STOP is generated. The interface will switch to Master Transmitter Mode if SMB0DAT is written while an active Master Receiver. Figure 23.6 shows a typical master read sequence. Two received data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’ interrupts occur before the ACK cycle in this mode. S SLA R A Data Byte A Data Byte N P Interrupts S = START Received by SMBus P = STOP Interface A = ACK N = NACK Transmitted by R = READ SMBus Interface SLA = Slave Address Figure 23.6. Typical Master Read Sequence Rev. 1.2 238

C8051F50x/F51x 23.5.3. Write Sequence (Slave) During a write sequence, an SMBus master writes data to a slave device. The slave in this transfer will be a receiver during the address byte, and a receiver during all data bytes. When slave events are enabled (INH = 0), the interface enters Slave Receiver Mode when a START followed by a slave address and direc- tion bit (WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the ACKRQ bit is set. The software must respond to the received slave address with an ACK, or ignore the received slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until the next START is detected. If the received slave address is acknowledged, zero or more data bytes are received. Software must write the ACK bit at that time to ACK or NACK the received byte. The interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 23.7 shows a typical slave write sequence. Two received data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’ interrupts occur before the ACK in this mode. S SLA W A Data Byte A Data Byte A P Interrupts S = START Received by SMBus P = STOP Interface A = ACK W = WRITE Transmitted by SLA = Slave Address SMBus Interface Figure 23.7. Typical Slave Write Sequence 239 Rev. 1.2

C8051F50x/F51x 23.5.4. Read Sequence (Slave) During a read sequence, an SMBus master reads data from a slave device. The slave in this transfer will be a receiver during the address byte, and a transmitter during all data bytes. When slave events are enabled (INH = 0), the interface enters Slave Receiver Mode (to receive the slave address) when a START followed by a slave address and direction bit (READ in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the ACKRQ bit is set. The software must respond to the received slave address with an ACK, or ignore the received slave address with a NACK. The interrupt will occur after the ACK cycle. If the received slave address is ignored, slave interrupts will be inhibited until the next START is detected. If the received slave address is acknowledged, zero or more data bytes are transmitted. If the received slave address is acknowledged, data should be written to SMB0DAT to be transmitted. The interface enters Slave Transmitter Mode, and transmits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is a NACK, SMB0DAT should not be written to before SI is cleared (Note: an error condition may be generated if SMB0DAT is written following a received NACK while in Slave Transmitter Mode). The interface exits Slave Transmitter Mode after receiving a STOP. Note that the interface will switch to Slave Receiver Mode if SMB0DAT is not written following a Slave Transmitter inter- rupt. Figure 23.8 shows a typical slave read sequence. Two transmitted data bytes are shown, though any number of bytes may be transmitted. Notice that all of the ‘data byte transferred’ interrupts occur after the ACK cycle in this mode. S SLA R A Data Byte A Data Byte N P Interrupts S = START Received by SMBus P = STOP Interface N = NACK R = READ Transmitted by SLA = Slave Address SMBus Interface Figure 23.8. Typical Slave Read Sequence 23.6. SMBus Status Decoding The current SMBus status can be easily decoded using the SMB0CN register. In the tables, STATUS VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. The shown response options are only the typical responses; application-specific procedures are allowed as long as they conform to the SMBus specification. Highlighted responses are allowed by hardware but do not con- form to the SMBus specification. Rev. 1.2 240

C8051F50x/F51x Table 23.4. SMBus Status Decoding Values Read Current SMbus State Typical Response Options Values to d e Write t c Mode Status Vector ACKRQ ARBLOST ACK STA STO ACK Next Status Vector Expe 1110 0 0 X A master START was gener- Load slave address + R/W into 0 0 X 1100 ated. SMB0DAT. 1100 0 0 0 A master data or address byte Set STA to restart transfer. 1 0 X 1110 was transmitted; NACK Abort transfer. 0 1 X — received. 0 0 1 A master data or address byte Load next data byte into 0 0 X 1100 was transmitted; ACK SMB0DAT. received. End transfer with STOP. 0 1 X — r e End transfer with STOP and start 1 1 X — mitt another transfer. s n Send repeated START. 1 0 X 1110 a Tr r Switch to Master Receiver Mode 0 0 X 1000 ste (clear SI without writing new data a to SMB0DAT). M 1000 1 0 X A master data byte was Acknowledge received byte; 0 0 1 1000 received; ACK requested. Read SMB0DAT. Send NACK to indicate last byte, 0 1 0 — and send STOP. Send NACK to indicate last byte, 1 1 0 1110 and send STOP followed by START. Send ACK followed by repeated 1 0 1 1110 START. Send NACK to indicate last byte, 1 0 0 1110 and send repeated START. Send ACK and switch to Master 0 0 1 1100 r e v Transmitter Mode (write to ei c SMB0DAT before clearing SI). e R r Send NACK and switch to Mas- 0 0 0 1100 ste ter Transmitter Mode (write to a SMB0DAT before clearing SI). M 241 Rev. 1.2

C8051F50x/F51x Table 23.4. SMBus Status Decoding Values Read Current SMbus State Typical Response Options Values to d e Write t c Mode Status Vector ACKRQ ARBLOST ACK STA STO ACK Next Status Vector Expe 0100 0 0 0 A slave byte was transmitted; No action required (expecting 0 0 X 0001 NACK received. STOP condition). 0 0 1 A slave byte was transmitted; Load SMB0DAT with next data 0 0 X 0100 r ACK received. byte to transmit. e mitt 0 1 X A Slave byte was transmitted; No action required (expecting 0 0 X 0001 s error detected. Master to end transfer). n a Tr 0101 0 X X An illegal STOP or bus error Clear STO. 0 0 X — e was detected while a Slave v a Transmission was in progress. Sl 0010 1 0 X A slave address + R/W was If Write, Acknowledge received 0 0 1 0000 received; ACK requested. address If Read, Load SMB0DAT with 0 0 1 0100 data byte; ACK received address NACK received address. 0 0 0 — 1 1 X Lost arbitration as master; If Write, Acknowledge received 0 0 1 0000 slave address + R/W received; address ACK requested. If Read, Load SMB0DAT with 0 0 1 0100 data byte; ACK received address NACK received address. 0 0 0 — Reschedule failed transfer; 1 0 0 1110 NACK received address. 0001 0 0 X A STOP was detected while Clear STO. 0 0 X — addressed as a Slave Trans- mitter or Slave Receiver. r 1 1 X Lost arbitration while attempt- No action required (transfer 0 0 0 — e eiv ing a STOP. complete/aborted). c e 0000 1 0 X A slave byte was received; Acknowledge received byte; 0 0 1 0000 R e ACK requested. Read SMB0DAT. v a NACK received byte. 0 0 0 — Sl 0010 0 1 X Lost arbitration while attempt- Abort failed transfer. 0 0 X — n o ing a repeated START. diti Reschedule failed transfer. 1 0 X 1110 n o 0001 0 1 X Lost arbitration due to a Abort failed transfer. 0 0 X — C detected STOP. r Reschedule failed transfer. 1 0 X 1110 o r Er 0000 1 1 X Lost arbitration while transmit- Abort failed transfer. 0 0 0 — s ting a data byte as master. u Reschedule failed transfer. 1 0 0 1110 B Rev. 1.2 242

C8051F50x/F51x 24. UART0 UART0 is an asynchronous, full duplex serial port offering a variety of data formatting options. A dedicated baud rate generator with a 16-bit timer and selectable prescaler is included, which can generate a wide range of baud rates (details in Section “24.1. Baud Rate Generator” on page 243). A received data FIFO allows UART0 to receive up to three data bytes before data is lost and an overflow occurs. UART0 has six associated SFRs. Three are used for the Baud Rate Generator (SBCON0, SBRLH0, and SBRLL0), two are used for data formatting, control, and status functions (SCON0, SMOD0), and one is used to send and receive data (SBUF0). The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0 always access the Transmit register. Reads of SBUF0 always access the buffered Receive register; it is not possible to read data from the Transmit register. With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually by software, allowing software to determine the cause of the UART0 interrupt (transmit complete or receive complete). If additional bytes are available in the Receive FIFO, the RI0 bit cannot be cleared by software. TX Baud Rate Generator Data Formatting Logic TX0 SMOD0 SBRLH0 SBRLL0 Overflow 01001000 CEPTPTPEDLDLBEBL TX Holding Pre-Scaler MS0S0 S0S0XS Register SYSCLK Timer (16-bit) (1, 4, 12, 48) EN Write to SBUF0 SBUF0 Control / Status Read of SBUF0 N 10 RU PSPS SCON0 RX FIFO SB0 SB0SB0 VR0RR0RE0EN0BX0BX0TI0RI0 (3 Deep) OEHRTR SBCON0 PT RX RX0 Logic UART0 Interrupt Figure 24.1. UART0 Block Diagram 24.1. Baud Rate Generator The UART0 baud rate is generated by a dedicated 16-bit timer which runs from the controller’s core clock (SYSCLK) and has prescaler options of 1, 4, 12, or 48. The timer and prescaler options combined allow for a wide selection of baud rates over many clock frequencies. The baud rate generator is configured using three registers: SBCON0, SBRLH0, and SBRLL0. The UART0 Baud Rate Generator Control Register (SBCON0, SFR Definition 24.4) enables or disables the baud rate generator, selects the clock source for the baud rate generator, and selects the prescaler value for the timer. The baud rate generator must be enabled for UART0 to function. Registers SBRLH0 and SBRLL0 contain a 16-bit reload value for the dedicated 16-bit timer. The internal timer counts up from the reload value on every clock tick. On timer overflows (0xFFFF to 0x0000), the timer is reloaded. The baud rate for UART0 is defined in Equation 24.1, where “BRG Clock” is the baud rate generator’s selected clock source. For reliable UART operation, it is recommended that the UART baud rate is not configured for baud rates faster than SYSCLK/16. Rev. 1.2 243

C8051F50x/F51x SYSCLK 1 1 Baud Rate = ------------------------------------------------------------------------------ x --- x ------------------------- (65536–(SBRLH0:SBRLL0)) 2 Prescaler Equation 24.1. UART0 Baud Rate A quick reference for typical baud rates and clock frequencies is given in Table 24.1. Table 24.1. Baud Rate Generator Settings for Standard Baud Rates Target Baud Actual Baud Baud Rate Oscillator SB0PS[1:0] Reload Value in Rate (bps) Rate (bps) Error Divide (Prescaler Bits) SBRLH0:SBRLL0 Factor 230400 230769 0.16% 208 11 0xFF98 115200 115385 0.16% 416 11 0xFF30 48 57600 57554 0.08% 834 11 0xFE5F = K 28800 28812 0.04% 1666 11 0xFCBF L C 14400 14397 0.02% 3334 11 0xF97D S Y 9600 9600 0.00% 5000 11 0xF63C S 2400 2400 0.00% 20000 11 0xD8F0 1200 1200 0.00% 40000 11 0xB1E0 230400 230769 0.16% 104 11 0xFFCC 115200 115385 0.16% 208 11 0xFF98 24 57600 57692 0.16% 416 11 0xFF30 = K 28800 28777 0.08% 834 11 0xFE5F L C 14400 14406 0.04% 1666 11 0xFCBF S Y 9600 9600 0.00% 2500 11 0xFB1E S 2400 2400 0.00% 10000 11 0xEC78 1200 1200 0.00% 20000 11 0xD8F0 230400 230769 0.16% 52 11 0xFFE6 115200 115385 0.16% 104 11 0xFFCC 12 57600 57692 0.16% 208 11 0xFF98 = K 28800 28846 0.16% 416 11 0xFF30 L C 14400 14388 0.08% 834 11 0xFE5F S Y 9600 9600 0.00% 1250 11 0xFD8F S 2400 2400 0.00% 5000 11 0xF63C 1200 1200 0.00% 10000 11 0xEC78 244 Rev. 1.2

C8051F50x/F51x 24.2. Data Format UART0 has a number of available options for data formatting. Data transfers begin with a start bit (logic low), followed by the data bits (sent LSB-first), a parity or extra bit (if selected), and end with one or two stop bits (logic high). The data length is variable between 5 and 8 bits. A parity bit can be appended to the data, and automatically generated and detected by hardware for even, odd, mark, or space parity. The stop bit length is selectable between 1 and 2 bit times, and a multi-processor communication mode is available for implementing networked UART buses. All of the data formatting options can be configured using the SMOD0 register, shown in SFR Definition 24.2. Figure 24.2 shows the timing for a UART0 transaction without parity or an extra bit enabled. Figure 24.3 shows the timing for a UART0 transaction with parity enabled (PE0 = 1). Figure 24.4 is an example of a UART0 transaction when the extra bit is enabled (XBE0 = 1). Note that the extra bit feature is not available when parity is enabled, and the second stop bit is only an option for data lengths of 6, 7, or 8 bits. MARK START BIT D0 D1 DN-2 DN-1 STOP STOP SPACE BIT 1 BIT 2 BIT TIMES Optional N bits; N = 5, 6, 7, or 8 (6,7,8 bit Data) Figure 24.2. UART0 Timing Without Parity or Extra Bit MARK START BIT D0 D1 DN-2 DN-1 PARITY STOP STOP SPACE BIT 1 BIT 2 BIT TIMES Optional N bits; N = 5, 6, 7, or 8 (6,7,8 bit Data) Figure 24.3. UART0 Timing With Parity MARK START BIT D0 D1 DN-2 DN-1 EXTRA STOP STOP SPACE BIT 1 BIT 2 BIT TIMES Optional N bits; N = 5, 6, 7, or 8 (6,7,8 bit Data) Figure 24.4. UART0 Timing With Extra Bit Rev. 1.2 245

C8051F50x/F51x 24.3. Configuration and Operation UART0 provides standard asynchronous, full duplex communication. It can operate in a point-to-point serial communications application, or as a node on a multi-processor serial interface. To operate in a point- to-point application, where there are only two devices on the serial bus, the MCE0 bit in SMOD0 should be cleared to 0. For operation as part of a multi-processor communications bus, the MCE0 and XBE0 bits should both be set to 1. In both types of applications, data is transmitted from the microcontroller on the TX0 pin, and received on the RX0 pin. The TX0 and RX0 pins are configured using the crossbar and the Port I/O registers, as detailed in Section “20. Port Input/Output” on page 177. In typical UART communications, The transmit (TX) output of one device is connected to the receive (RX) input of the other device, either directly or through a bus transceiver, as shown in Figure 24.5. TX PC USB CP2102 USB Port USB-to-UART RX C8051Fxxx Bridge OR TX TX MCU C8051Fxxx RX RX Figure 24.5. Typical UART Interconnect Diagram 24.3.1. Data Transmission Data transmission begins when software writes a data byte to the SBUF0 register. The TI0 Transmit Inter- rupt Flag (SCON0.1) will be set at the end of any transmission (the beginning of the stop-bit time). If enabled, an interrupt will occur when TI0 is set. If the extra bit function is enabled (XBE0 = 1) and the parity function is disabled (PE0 = 0), the value of the TBX0 (SCON0.3) bit will be sent in the extra bit position. When the parity function is enabled (PE0 = 1), hardware will generate the parity bit according to the selected parity type (selected with S0PT[1:0]), and append it to the data field. Note: when parity is enabled, the extra bit function is not available. 24.3.2. Data Reception Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is received, the data byte will be stored in the receive FIFO if the following conditions are met: the receive FIFO (3 bytes deep) must not be full, and the stop bit(s) must be logic 1. In the event that the receive FIFO is full, the incoming byte will be lost, and a Receive FIFO Overrun Error will be generated (OVR0 in register SCON0 will be set to logic 1). If the stop bit(s) were logic 0, the incoming data will not be stored in the receive FIFO. If the reception conditions are met, the data is stored in the receive FIFO, and the RI0 flag will be set. Note: when MCE0 = 1, RI0 will only be set if the extra bit was equal to 1. Data can be read from the receive FIFO by reading the SBUF0 register. The SBUF0 register represents the oldest byte in the FIFO. After SBUF0 is read, the next byte in the FIFO is immediately loaded into SBUF0, and space is made available in the FIFO for another incoming byte. If enabled, an interrupt will occur when RI0 is set.RI0 can only be cleared to 0 by software when there is no more information in the FIFO. The recom- mended procedure to empty the FIFO contents is: 1. Clear RI0 to 0. 2. Read SBUF0. 3. Check RI0, and repeat starting at step 1 if RI0 is set to 1. 246 Rev. 1.2

C8051F50x/F51x If the extra bit function is enabled (XBE0 = 1) and the parity function is disabled (PE0 = 0), the extra bit for the oldest byte in the FIFO can be read from the RBX0 bit (SCON0.2). If the extra bit function is not enabled, the value of the stop bit for the oldest FIFO byte will be presented in RBX0. When the parity func- tion is enabled (PE0 = 1), hardware will check the received parity bit against the selected parity type (selected with S0PT[1:0]) when receiving data. If a byte with parity error is received, the PERR0 flag will be set to 1. This flag must be cleared by software. Note: when parity is enabled, the extra bit function is not available. 24.3.3. Multiprocessor Communications UART0 supports multiprocessor communication between a master processor and one or more slave pro- cessors by special use of the extra data bit. When a master processor wants to transmit to one or more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte in that its extra bit is logic 1; in a data byte, the extra bit is always set to logic 0. Setting the MCE0 bit (SMOD0.7) of a slave processor configures its UART such that when a stop bit is received, the UART will generate an interrupt only if the extra bit is logic 1 (RBX0 = 1) signifying an address byte has been received. In the UART interrupt handler, software will compare the received address with the slave's own assigned address. If the addresses match, the slave will clear its MCE0 bit to enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0 bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all trans- missions until it receives the next address byte. Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master processor can be configured to receive all transmissions or a protocol can be implemented such that the master/slave role is temporarily reversed to enable half-duplex transmission between the original master and slave(s). Master Slave Slave Slave Device Device Device Device V+ RX TX RX TX RX TX RX TX Figure 24.6. UART Multi-Processor Mode Interconnect Diagram Rev. 1.2 247

C8051F50x/F51x SFR Definition 24.1. SCON0: Serial Port 0 Control Bit 7 6 5 4 3 2 1 0 Name OVR0 PERR0 THRE0 REN0 TBX0 RBX0 TI0 RI0 Type R/W R/W R R/W R/W R/W R/W R/W Reset 0 0 1 0 0 0 0 0 SFR Address = 0x98; Bit-Addressable; SFR Page = 0x00 Bit Name Function 7 OVR0 Receive FIFO Overrun Flag. 0: Receive FIFO Overrun has not occurred 1: Receive FIFO Overrun has occurred; A received character has been discarded due to a full FIFO. 6 PERR0 Parity Error Flag. When parity is enabled, this bit indicates that a parity error has occurred. It is set to 1 when the parity of the oldest byte in the FIFO does not match the selected Parity Type. 0: Parity error has not occurred 1: Parity error has occurred. This bit must be cleared by software. 5 THRE0 Transmit Holding Register Empty Flag. 0: Transmit Holding Register not Empty—do not write to SBUF0. 1: Transmit Holding Register Empty—it is safe to write to SBUF0. 4 REN0 Receive Enable. This bit enables/disables the UART receiver. When disabled, bytes can still be read from the receive FIFO. 0: UART1 reception disabled. 1: UART1 reception enabled. 3 TBX0 Extra Transmission Bit. The logic level of this bit will be assigned to the extra transmission bit when XBE0 is set to 1. This bit is not used when Parity is enabled. 2 RBX0 Extra Receive Bit. RBX0 is assigned the value of the extra bit when XBE1 is set to 1. If XBE1 is cleared to 0, RBX1 will be assigned the logic level of the first stop bit. This bit is not valid when Parity is enabled. 1 TI0 Transmit Interrupt Flag. Set to a 1 by hardware after data has been transmitted, at the beginning of the STOP bit. When the UART0 interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software. 0 RI0 Receive Interrupt Flag. Set to 1 by hardware when a byte of data has been received by UART0 (set at the STOP bit sampling time). When the UART0 interrupt is enabled, setting this bit to 1 causes the CPU to vector to the UART0 interrupt service routine. This bit must be cleared manually by software. Note that RI0 will remain set to ‘1’ as long as there is data still in the UART FIFO. After the last byte has been shifted from the FIFO to SBUF0, RI0 can be cleared. 248 Rev. 1.2

C8051F50x/F51x SFR Definition 24.2. SMOD0: Serial Port 0 Control Bit 7 6 5 4 3 2 1 0 Name MCE0 S0PT[1:0] PE0 S0DL[1:0] XBE0 SBL0 Type R/W R/W R R/W R/W R/W R/W R/W Reset 0 0 0 0 1 1 0 0 SFR Address = 0xA9; SFR Page = 0x00 Bit Name Function 7 MCE0 Multiprocessor Communication Enable. 0: RI0 will be activated if stop bit(s) are 1. 1: RI0 will be activated if stop bit(s) and extra bit are 1. Extra bit must be enabled using XBE0. 6:5 S0PT[1:0] Parity Type Select Bits. 00: Odd Parity 01: Even Parity 10: Mark Parity 11: Space Parity. 4 PE0 Parity Enable. This bit enables hardware parity generation and checking. The parity type is selected by bits S0PT[1:0] when parity is enabled. 0: Hardware parity is disabled. 1: Hardware parity is enabled. 3:2 S0DL[1:0] Data Length. 00: 5-bit data 01: 6-bit data 10: 7-bit data 11: 8-bit data 1 XBE0 Extra Bit Enable. When enabled, the value of TBX0 will be appended to the data field 0: Extra Bit is disabled. 1: Extra Bit is enabled. 0 SBL0 Stop Bit Length. 0: Short—stop bit is active for one bit time 1: Long—stop bit is active for two bit times (data length = 6, 7, or 8 bits), or 1.5 bit times (data length = 5 bits). Rev. 1.2 249

C8051F50x/F51x SFR Definition 24.3. SBUF0: Serial (UART0) Port Data Buffer Bit 7 6 5 4 3 2 1 0 Name SBUF0[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x99; SFR Page = 0x00 Bit Name Function 7:0 SBUF0[7:0] Serial Data Buffer Bits 7–0 (MSB–LSB). This SFR accesses two registers; a transmit shift register and a receive latch register. When data is written to SBUF0, it goes to the transmit shift register and is held for serial transmission. Writing a byte to SBUF0 initiates the transmission. A read of SBUF0 returns the contents of the receive latch. SFR Definition 24.4. SBCON0: UART0 Baud Rate Generator Control Bit 7 6 5 4 3 2 1 0 Name Reserved SB0RUN Reserved Reserved Reserved Reserved SB0PS[1:0] Type R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xAB; SFR Page = 0x0F Bit Name Function 7 Reserved Read = 0b; Must Write 0b; 6 SB0RUN Baud Rate Generator Enable. 0: Baud Rate Generator disabled. UART0 will not function. 1: Baud Rate Generator enabled. 5:2 Reserved Read = 0000b; Must Write = 0000b; 1:0 SB0PS[1:0] Baud Rate Prescaler Select. 00: Prescaler = 12. 01: Prescaler = 4. 10: Prescaler = 48. 11: Prescaler = 1. 250 Rev. 1.2

C8051F50x/F51x SFR Definition 24.5. SBRLH0: UART0 Baud Rate Generator Reload High Byte Bit 7 6 5 4 3 2 1 0 Name SBRLH0[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xAD; SFR Page = 0x0F Bit Name Function 7:0 SBRLH0[7:0] High Byte of Reload Value for UART0 Baud Rate Generator. This value is loaded into the high byte of the UART0 baud rate generator when the counter overflows from 0xFFFF to 0x0000. SFR Definition 24.6. SBRLL0: UART0 Baud Rate Generator Reload Low Byte Bit 7 6 5 4 3 2 1 0 Name SBRLL0[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xAC; SFR Page = 0x0F Bit Name Function 7:0 SBRLL0[7:0] Low Byte of Reload Value for UART0 Baud Rate Generator. This value is loaded into the low byte of the UART0 baud rate generator when the counter overflows from 0xFFFF to 0x0000. Rev. 1.2 251

C8051F50x/F51x 25. Enhanced Serial Peripheral Interface (SPI0) The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports mul- tiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can also be configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional gen- eral purpose port I/O pins can be used to select multiple slave devices in master mode. SFR Bus SPI0CKR SPI0CFG SPI0CN SCR7SCR6SCR5SCR4SCR3SCR2SCR1SCR0 SPIBSYMSTENCKPHACKPOLSLVSELNSSINSRMTRXBMT SPIFWCOLMODFRXOVRNNSSMD1NSSMD0TXBMTSPIEN Clock Divide SYSCLK Logic SPI CONTROL LOGIC SPI IRQ Data Path Pin Interface Control Control Tx Data MOSI C SPI0DAT R SCK Transmit Data Buffer O Pin S Control Port I/O S 7 6S5hift4 Re3gist2er1 0 Rx Data Logic MISO B A R Receive Data Buffer NSS Write Read SPI0DAT SPI0DAT SFR Bus Figure 25.1. SPI Block Diagram Rev. 1.2 252

C8051F50x/F51x 25.1. Signal Descriptions The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below. 25.1.1. Master Out, Slave In (MOSI) The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operat- ing as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire mode. 25.1.2. Master In, Slave Out (MISO) The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device. It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operat- ing as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is always driven by the MSB of the shift register. 25.1.3. Serial Clock (SCK) The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 gen- erates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is not selected (NSS = 1) in 4-wire slave mode. 25.1.4. Slave Select (NSS) The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0 bits in the SPI0CN register. There are three possible modes that can be selected with these bits: 1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode. Since no select signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This is intended for point-to- point communication between a master and one slave. 2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When operating as a master, a 1-to-0 transition of the NSS signal disables the master function of SPI0 so that multiple master devices can be used on the same SPI bus. 3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This configuration should only be used when operating SPI0 as a master device. See Figure 25.2, Figure 25.3, and Figure 25.4 for typical connection diagrams of the various operational modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or 3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will be mapped to a pin on the device. See Section “20. Port Input/Output” on page 177 for general purpose port I/O and crossbar information. 253 Rev. 1.2

C8051F50x/F51x 25.2. SPI0 Master Mode Operation A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic 1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by reading SPI0DAT. When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when NSS- MD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in this mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and a Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0 must be manually re-enabled in software under these circumstances. In multi-master systems, devices will typically default to being slave devices while they are not acting as the system master device. In multi-mas- ter mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins. Figure 25.2 shows a connection diagram between two master devices in multiple-master mode. 3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave devices that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 25.3 shows a connection diagram between a master device in 3-wire master mode and a slave device. 4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be addressed using general-purpose I/O pins. Figure 25.4 shows a connection diagram for a master device in 4-wire master mode and two slave devices. Rev. 1.2 254

C8051F50x/F51x NSS GPIO MISO MISO Master Master MOSI MOSI Device 1 Device 2 SCK SCK GPIO NSS Figure 25.2. Multiple-Master Mode Connection Diagram Master Slave Device MISO MISO Device MOSI MOSI SCK SCK Figure 25.3. 3-Wire Single Master and 3-Wire Single Slave Mode Connection Diagram Master MISO MISO Slave Device MOSI MOSI Device SCK SCK NSS NSS GPIO MISO Slave MOSI Device SCK NSS Figure 25.4. 4-Wire Single Master Mode and 4-Wire Slave Mode Connection Diagram 255 Rev. 1.2

C8051F50x/F51x 25.3. SPI0 Slave Mode Operation When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK sig- nal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted through the shift reg- ister, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are double- buffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit buffer will immediately be transferred into the shift register. When the shift register already contains data, the SPI will load the shift register with the transmit buffer’s contents after the last SCK edge of the next (or current) SPI transfer. When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0, and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS sig- nal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer. Figure 25.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master device. 3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not used in this mode, and is not mapped to an external port pin through the crossbar. Since there is no way of uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter that determines when a full byte has been received. The bit counter can only be reset by disabling and re- enabling SPI0 with the SPIEN bit. Figure 25.3 shows a connection diagram between a slave device in 3- wire slave mode and a master device. 25.4. SPI0 Interrupt Sources When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to logic 1: All of the following bits must be cleared by software. 1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This flag can occur in all SPI0 modes. 2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur in all SPI0 modes. 3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master, and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master device to access the bus. 4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave, and a transfer is completed and the receive buffer still holds an unread byte from a previous transfer. The new byte is not transferred to the receive buffer, allowing the previously received data byte to be read. The data byte which caused the overrun is lost. Rev. 1.2 256

C8051F50x/F51x 25.5. Serial Clock Phase and Polarity Four combinations of serial clock phase and polarity can be selected using the clock control bits in the SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases (edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low clock. Both master and slave devices must be configured to use the same clock phase and polarity. SPI0 should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The clock and data line relationships for master mode are shown in Figure 25.5. For slave mode, the clock and data relationships are shown in Figure 25.6 and Figure 25.7. CKPHA must be set to 0 on both the master and slave SPI when communicating between two of the following devices: C8051F04x, C8051F06x, C8051F12x, C8051F31x, C8051F32x, and C8051F33x. The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 25.3 controls the master mode serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured as a master, the maximum data transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz, whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4- wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec) must be less than 1/10 the system clock frequency. In the special case where the master only wants to transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency. This is provided that the master issues SCK, NSS, and the serial input data synchronously with the slave’s system clock. SCK (CKPOL=0, CKPHA=0) SCK (CKPOL=0, CKPHA=1) SCK (CKPOL=1, CKPHA=0) SCK (CKPOL=1, CKPHA=1) MISO/MOSI MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 NSS (Must Remain High in Multi-Master Mode) Figure 25.5. Master Mode Data/Clock Timing 257 Rev. 1.2

C8051F50x/F51x SCK (CKPOL=0, CKPHA=0) SCK (CKPOL=1, CKPHA=0) MOSI MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 MISO MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 NSS (4-Wire Mode) Figure 25.6. Slave Mode Data/Clock Timing (CKPHA = 0) SCK (CKPOL=0, CKPHA=1) SCK (CKPOL=1, CKPHA=1) MOSI MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 MISO MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 NSS (4-Wire Mode) Figure 25.7. Slave Mode Data/Clock Timing (CKPHA = 1) 25.6. SPI Special Function Registers SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate Register. The four special function registers related to the operation of the SPI0 Bus are described in the following figures. Rev. 1.2 258

C8051F50x/F51x SFR Definition 25.1. SPI0CFG: SPI0 Configuration Bit 7 6 5 4 3 2 1 0 Name SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT Type R R/W R/W R/W R R R R Reset 0 0 0 0 0 1 1 1 SFR Address = 0xA1; SFR Page = 0x00 Bit Name Function 7 SPIBSY SPI Busy. This bit is set to logic 1 when a SPI transfer is in progress (master or slave mode). 6 MSTEN Master Mode Enable. 0: Disable master mode. Operate in slave mode. 1: Enable master mode. Operate as a master. 5 CKPHA SPI0 Clock Phase. 0: Data centered on first edge of SCK period.* 1: Data centered on second edge of SCK period.* 4 CKPOL SPI0 Clock Polarity. 0: SCK line low in idle state. 1: SCK line high in idle state. 3 SLVSEL Slave Selected Flag. This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the instantaneous value at the NSS pin, but rather a de-glitched ver- sion of the pin input. 2 NSSIN NSS Instantaneous Pin Input. This bit mimics the instantaneous value that is present on the NSS port pin at the time that the register is read. This input is not de-glitched. 1 SRMT Shift Register Empty (valid in slave mode only). This bit will be set to logic 1 when all data has been transferred in/out of the shift register, and there is no new information available to read from the transmit buffer or write to the receive buffer. It returns to logic 0 when a data byte is transferred to the shift register from the transmit buffer or by a transition on SCK. SRMT = 1 when in Master Mode. 0 RXBMT Receive Buffer Empty (valid in slave mode only). This bit will be set to logic 1 when the receive buffer has been read and contains no new information. If there is new information available in the receive buffer that has not been read, this bit will return to logic 0. RXBMT = 1 when in Master Mode. Note: In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data on MISO is sampled one SYSCLK before the end of each data bit, to provide maximum settling time for the slave device. See Table 25.1 for timing parameters. 259 Rev. 1.2

C8051F50x/F51x SFR Definition 25.2. SPI0CN: SPI0 Control Bit 7 6 5 4 3 2 1 0 Name SPIF WCOL MODF RXOVRN NSSMD[1:0] TXBMT SPIEN Type R/W R/W R/W R/W R/W R R/W Reset 0 0 0 0 0 1 1 0 SFR Address = 0xF8; Bit-Addressable; SFR Page = 0x00 Bit Name Function 7 SPIF SPI0 Interrupt Flag. This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled, setting this bit causes the CPU to vector to the SPI0 interrupt service rou- tine. This bit is not automatically cleared by hardware. It must be cleared by soft- ware. 6 WCOL Write Collision Flag. This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) to indicate a write to the SPI0 data register was attempted while a data transfer was in progress. It must be cleared by software. 5 MODF Mode Fault Flag. This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a mas- ter mode collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not automatically cleared by hardware. It must be cleared by software. 4 RXOVRN Receive Overrun Flag (valid in slave mode only). This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive buffer still holds unread data from a previous transfer and the last bit of the current transfer is shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must be cleared by software. 3:2 NSSMD[1:0] Slave Select Mode. Selects between the following NSS operation modes: (See Section 25.2 and Section 25.3). 00: 3-Wire Slave or 3-Wire Master Mode. NSS signal is not routed to a port pin. 01: 4-Wire Slave or Multi-Master Mode (Default). NSS is an input to the device. 1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will assume the value of NSSMD0. 1 TXBMT Transmit Buffer Empty. This bit will be set to logic 0 when new data has been written to the transmit buffer. When data in the transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1, indicating that it is safe to write a new byte to the transmit buffer. 0 SPIEN SPI0 Enable. 0: SPI disabled. 1: SPI enabled. Rev. 1.2 260

C8051F50x/F51x SFR Definition 25.3. SPI0CKR: SPI0 Clock Rate Bit 7 6 5 4 3 2 1 0 Name SCR[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xA2; SFR Page = 0x00 Bit Name Function 7:0 SCR[7:0] SPI0 Clock Rate. These bits determine the frequency of the SCK output when the SPI0 module is configured for master mode operation. The SCK clock frequency is a divided ver- sion of the system clock, and is given in the following equation, where SYSCLK is the system clock frequency and SPI0CKR is the 8-bit value held in the SPI0CKR register. SYSCLK f = ---------------------------------------------------------------- SCK 2 x (SPI0CKR[7:0]+1) for 0 <= SPI0CKR <= 255 Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04, 2000000 f = ------------------------------ SCK 2 x (4+1) f = 200 kHz SCK SFR Definition 25.4. SPI0DAT: SPI0 Data Bit 7 6 5 4 3 2 1 0 Name SPI0DAT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xA3; SFR Page = 0x00 Bit Name Function 7:0 SPI0DAT[7:0] SPI0 Transmit and Receive Data. The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT places the data into the transmit buffer and initiates a transfer when in Master Mode. A read of SPI0DAT returns the contents of the receive buffer. 261 Rev. 1.2

C8051F50x/F51x SCK* T T MCKH MCKL T T MIS MIH MISO MOSI * SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1. Figure 25.8. SPI Master Timing (CKPHA = 0) SCK* T T MCKH MCKL T T MIS MIH MISO MOSI * SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1. Figure 25.9. SPI Master Timing (CKPHA = 1) Rev. 1.2 262

C8051F50x/F51x NSS T T T SE CKL SD SCK* T CKH T T SIS SIH MOSI T T T SEZ SOH SDZ MISO * SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1. Figure 25.10. SPI Slave Timing (CKPHA = 0) NSS T T T SE CKL SD SCK* T CKH T T SIS SIH MOSI T T T T SEZ SOH SLH SDZ MISO * SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1. Figure 25.11. SPI Slave Timing (CKPHA = 1) 263 Rev. 1.2

C8051F50x/F51x Table 25.1. SPI Slave Timing Parameters Parameter Description Min Max Units Master Mode Timing* (See Figure 25.8 and Figure 25.9) TMCKH SCK High Time 1 x TSYSCLK — ns TMCKL SCK Low Time 1 x TSYSCLK — ns TMIS MISO Valid to SCK Shift Edge 1 x TSYSCLK + 20 — ns T SCK Shift Edge to MISO Change 0 — ns MIH Slave Mode Timing* (See Figure 25.10 and Figure 25.11) TSE NSS Falling to First SCK Edge 2 x TSYSCLK — ns TSD Last SCK Edge to NSS Rising 2 x TSYSCLK — ns TSEZ NSS Falling to MISO Valid — 4 x TSYSCLK ns TSDZ NSS Rising to MISO High-Z — 4 x TSYSCLK ns TCKH SCK High Time 5 x TSYSCLK — ns TCKL SCK Low Time 5 x TSYSCLK — ns TSIS MOSI Valid to SCK Sample Edge 2 x TSYSCLK — ns TSIH SCK Sample Edge to MOSI Change 2 x TSYSCLK — ns TSOH SCK Shift Edge to MISO Change — 4 x TSYSCLK ns TSLH Last SCK Edge to MISO Change 6 x TSYSCLK 8 x TSYSCLK ns (CKPHA = 1 ONLY) *Note: T is equal to one period of the device system clock (SYSCLK). SYSCLK Rev. 1.2 264

C8051F50x/F51x 26. Timers Each MCU includes four counter/timers: two are 16-bit counter/timers compatible with those found in the standard 8051, and two are 16-bit auto-reload timer for use with the ADC, SMBus, or for general purpose use. These timers can be used to measure time intervals, count external events and generate periodic interrupt requests. Timer 0 and Timer 1 are nearly identical and have four primary modes of operation. Timer 2 and Timer 3 offer 16-bit and split 8-bit timer functionality with auto-reload. Timer 0 and Timer 1 Modes Timer 2 Modes Timer 3 Modes 13-bit counter/timer 16-bit timer with auto-reload 16-bit timer with auto-reload 16-bit counter/timer 8-bit counter/timer with Two 8-bit timers with auto-reload Two 8-bit timers with auto-reload auto-reload Two 8-bit counter/timers (Timer 0 only) Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits (T1M– T0M) and the Clock Scale bits (SCA1–SCA0). The Clock Scale bits define a pre-scaled clock from which Timer 0 and/or Timer 1 may be clocked (See SFR Definition 26.1 for pre-scaled clock selection).Timer 0/1 may then be configured to use this pre-scaled clock signal or the system clock. Timer 2 and Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator clock source divided by 8. Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer register is incremented on each high-to-low transition at the selected input pin (T0 or T1). Events with a fre- quency of up to one-fourth the system clock frequency can be counted. The input signal need not be peri- odic, but it should be held at a given level for at least two full system clock cycles to ensure the level is properly sampled. Rev. 1.2 265

C8051F50x/F51x SFR Definition 26.1. CKCON: Clock Control Bit 7 6 5 4 3 2 1 0 Name T3MH T3ML T2MH T2ML T1M T0M SCA[1:0] Type R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x8E; SFR Page = All Pages Bit Name Function 7 T3MH Timer 3 High Byte Clock Select. Selects the clock supplied to the Timer 3 high byte (split 8-bit timer mode only). 0: Timer 3 high byte uses the clock defined by the T3XCLK bit in TMR3CN. 1: Timer 3 high byte uses the system clock. 6 T3ML Timer 3 Low Byte Clock Select. Selects the clock supplied to Timer 3. Selects the clock supplied to the lower 8-bit timer in split 8-bit timer mode. 0: Timer 3 low byte uses the clock defined by the T3XCLK bit in TMR3CN. 1: Timer 3 low byte uses the system clock. 5 T2MH Timer 2 High Byte Clock Select. Selects the clock supplied to the Timer 2 high byte (split 8-bit timer mode only). 0: Timer 2 high byte uses the clock defined by the T2XCLK bit in TMR2CN. 1: Timer 2 high byte uses the system clock. 4 T2ML Timer 2 Low Byte Clock Select. Selects the clock supplied to Timer 2. If Timer 2 is configured in split 8-bit timer mode, this bit selects the clock supplied to the lower 8-bit timer. 0: Timer 2 low byte uses the clock defined by the T2XCLK bit in TMR2CN. 1: Timer 2 low byte uses the system clock. 3 T1 Timer 1 Clock Select. Selects the clock source supplied to Timer 1. Ignored when C/T1 is set to 1. 0: Timer 1 uses the clock defined by the prescale bits SCA[1:0]. 1: Timer 1 uses the system clock. 2 T0 Timer 0 Clock Select. Selects the clock source supplied to Timer 0. Ignored when C/T0 is set to 1. 0: Counter/Timer 0 uses the clock defined by the prescale bits SCA[1:0]. 1: Counter/Timer 0 uses the system clock. 1:0 SCA[1:0] Timer 0/1 Prescale Bits. These bits control the Timer 0/1 Clock Prescaler: 00: System clock divided by 12 01: System clock divided by 4 10: System clock divided by 48 11: External clock divided by 8 (synchronized with the system clock) 266 Rev. 1.2

C8051F50x/F51x 26.1. Timer 0 and Timer 1 Each timer is implemented as a 16-bit register accessed as two separate bytes: a low byte (TL0 or TL1) and a high byte (TH0 or TH1). The Counter/Timer Control register (TCON) is used to enable Timer 0 and Timer 1 as well as indicate status. Timer 0 interrupts can be enabled by setting the ET0 bit in the IE regis- ter (Section “14.2. Interrupt Register Descriptions” on page 120); Timer 1 interrupts can be enabled by set- ting the ET1 bit in the IE register (Section “14.2. Interrupt Register Descriptions” on page 120). Both counter/timers operate in one of four primary modes selected by setting the Mode Select bits T1M1–T0M0 in the Counter/Timer Mode register (TMOD). Each timer can be configured independently. Each operating mode is described below. 26.1.1. Mode 0: 13-bit Counter/Timer Timer 0 and Timer 1 operate as 13-bit counter/timers in Mode 0. The following describes the configuration and operation of Timer 0. However, both timers operate identically, and Timer 1 is configured in the same manner as described for Timer 0. The TH0 register holds the eight MSBs of the 13-bit counter/timer. TL0 holds the five LSBs in bit positions TL0.4–TL0.0. The three upper bits of TL0 (TL0.7–TL0.5) are indeterminate and should be masked out or ignored when reading. As the 13-bit timer register increments and overflows from 0x1FFF (all ones) to 0x0000, the timer overflow flag TF0 (TCON.5) is set and an interrupt will occur if Timer 0 interrupts are enabled. The C/T0 bit (TMOD.2) selects the counter/timer's clock source. When C/T0 is set to logic 1, high-to-low transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section “20.3. Priority Crossbar Decoder” on page 180 for information on selecting and configuring external I/O pins). Clearing C/T selects the clock defined by the T0M bit (CKCON.3). When T0M is set, Timer 0 is clocked by the system clock. When T0M is cleared, Timer 0 is clocked by the source selected by the Clock Scale bits in CKCON (see SFR Definition 26.1). Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal INT0 is active as defined by bit IN0PL in register IT01CF (see SFR Definition 14.7). Setting GATE0 to 1 allows the timer to be controlled by the external input signal INT0 (see Section “14.2. Interrupt Register Descriptions” on page 120), facilitating pulse width measurements. TR0 GATE0 INT0 Counter/Timer 0 X X Disabled 1 0 X Enabled 1 1 0 Disabled 1 1 1 Enabled Note: X = Don't Care Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial value before the timer is enabled. TL1 and TH1 form the 13-bit register for Timer 1 in the same manner as described above for TL0 and TH0. Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0. The input signal INT1 is used with Timer 1; the INT1 polarity is defined by bit IN1PL in register IT01CF (see SFR Definition 14.7). Rev. 1.2 267

C8051F50x/F51x CKCON TMOD IT01CF T T T T T T S S G C T T G C T T I I I I I I I I 3 3 2 2 1 0 CC A / 1 1 A / 0 0 N N N N N N N N MMMMMMA A T T MM T T MM 1 1 1 1 0 0 0 0 H L H L 1 0 E 1 1 0 E 0 1 0 P S S S P S S S 1 0 L L L L L L L L 2 1 0 2 1 0 Pre-scaled Clock 0 0 SYSCLK 1 1 TF1 T0 TR1 TCLK TL0 TH0 TF0 Interrupt TR0 TR0 (5 bits) (8 bits) N IE1 GATE0 O IT1 Crossbar TC IIET00 IN0PL /INT0 XOR Figure 26.1. T0 Mode 0 Block Diagram 26.1.2. Mode 1: 16-bit Counter/Timer Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The counter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0. 26.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload Mode 2 configures Timer 0 and Timer 1 to operate as 8-bit counter/timers with automatic reload of the start value. TL0 holds the count and TH0 holds the reload value. When the counter in TL0 overflows from all ones to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0. If Timer 0 interrupts are enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is not changed. TL0 must be initialized to the desired value before enabling the timer for the first count to be correct. When in Mode 2, Timer 1 operates identically to Timer 0. Both counter/timers are enabled and configured in Mode 2 in the same manner as Mode 0. Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or when the input signal INT0 is active as defined by bit IN0PL in register IT01CF (see Section “14.3. External Interrupts INT0 and INT1” on page 126 for details on the external input signals INT0 and INT1). 268 Rev. 1.2

C8051F50x/F51x CKCON TMOD IT01CF T T T T T TSS GC T T GC T T I I I I I I I I 3 3 2 2 1 0CC A / 1 1 A / 0 0 NNNNNNNN MMMMMMAA T TMMT TMM 1 1 1 1 0 0 0 0 H LHL 1 0 E 1 1 0 E 0 1 0 P S S S P S S S 1 0 L L L L L L L L 2 1 0 2 1 0 Pre-scaled Clock 0 0 SYSCLK 1 1 T0 TF1 TCLK TL0 TR1 TF0 Interrupt (8 bits) TR0 TR0 ON IIET11 Crossbar GATE0 TC IIET00 TH0 Reload (8 bits) IN0PL /INT0 XOR Figure 26.2. T0 Mode 2 Block Diagram 26.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only) In Mode 3, Timer 0 is configured as two separate 8-bit counter/timers held in TL0 and TH0. The counter/timer in TL0 is controlled using the Timer 0 control/status bits in TCON and TMOD: TR0, C/T0, GATE0 and TF0. TL0 can use either the system clock or an external input signal as its timebase. The TH0 register is restricted to a timer function sourced by the system clock or prescaled clock. TH0 is enabled using the Timer 1 run control bit TR1. TH0 sets the Timer 1 overflow flag TF1 on overflow and thus controls the Timer 1 interrupt. Timer 1 is inactive in Mode 3. When Timer 0 is operating in Mode 3, Timer 1 can be operated in Modes 0, 1 or 2, but cannot be clocked by external signals nor set the TF1 flag and generate an interrupt. However, the Timer 1 overflow can be used to generate baud rates for the SMBus and/or UART, and/or initiate ADC conversions. While Timer 0 is operating in Mode 3, Timer 1 run control is handled through its mode set- tings. To run Timer 1 while Timer 0 is in Mode 3, set the Timer 1 Mode as 0, 1, or 2. To disable Timer 1, configure it for Mode 3. Rev. 1.2 269

C8051F50x/F51x CKCON TMOD TTTTTTSS GCT TGCT T 3 3 2 2 1 0CC A / 1 1 A / 0 0 MMMMMMAA T TMMT TMM HLHL 1 0 E 1 1 0 E 0 1 0 1 0 Pre-scaled Clock 0 TR1 TH0 TF1 Interrupt (8 bits) TR1 TF0 Interrupt SYSCLK 1 TR0 0 N IE1 O IT1 C IE0 T IT0 1 T0 TL0 (8 bits) TR0 Crossbar GATE0 IN0PL /INT0 XOR Figure 26.3. T0 Mode 3 Block Diagram 270 Rev. 1.2

C8051F50x/F51x SFR Definition 26.2. TCON: Timer Control Bit 7 6 5 4 3 2 1 0 Name TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x88; Bit-Addressable; SFR Page = All Pages Bit Name Function 7 TF1 Timer 1 Overflow Flag. Set to 1 by hardware when Timer 1 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 1 interrupt service routine. 6 TR1 Timer 1 Run Control. Timer 1 is enabled by setting this bit to 1. 5 TF0 Timer 0 Overflow Flag. Set to 1 by hardware when Timer 0 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 0 interrupt service routine. 4 TR0 Timer 0 Run Control. Timer 0 is enabled by setting this bit to 1. 3 IE1 External Interrupt 1. This flag is set by hardware when an edge/level of type defined by IT1 is detected. It can be cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 1 service routine in edge-triggered mode. 2 IT1 Interrupt 1 Type Select. This bit selects whether the configured INT1 interrupt will be edge or level sensitive. INT1 is configured active low or high by the IN1PL bit in the IT01CF register (see SFR Definition 14.7). 0: INT1 is level triggered. 1: INT1 is edge triggered. 1 IE0 External Interrupt 0. This flag is set by hardware when an edge/level of type defined by IT1 is detected. It can be cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 0 service routine in edge-triggered mode. 0 IT0 Interrupt 0 Type Select. This bit selects whether the configured INT0 interrupt will be edge or level sensitive. INT0 is configured active low or high by the IN0PL bit in register IT01CF (see SFR Definition 14.7). 0: INT0 is level triggered. 1: INT0 is edge triggered. Rev. 1.2 271

C8051F50x/F51x SFR Definition 26.3. TMOD: Timer Mode Bit 7 6 5 4 3 2 1 0 Name GATE1 C/T1 T1M[1:0] GATE0 C/T0 T0M[1:0] Type R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x89; SFR Page = All Pages Bit Name Function 7 GATE1 Timer 1 Gate Control. 0: Timer 1 enabled when TR1 = 1 irrespective of INT1 logic level. 1: Timer 1 enabled only when TR1 = 1 AND INT1 is active as defined by bit IN1PL in register IT01CF (see SFR Definition 14.7). 6 C/T1 Counter/Timer 1 Select. 0: Timer: Timer 1 incremented by clock defined by T1M bit in register CKCON. 1: Counter: Timer 1 incremented by high-to-low transitions on external pin (T1). 5:4 T1M[1:0] Timer 1 Mode Select. These bits select the Timer 1 operation mode. 00: Mode 0, 13-bit Counter/Timer 01: Mode 1, 16-bit Counter/Timer 10: Mode 2, 8-bit Counter/Timer with Auto-Reload 11: Mode 3, Timer 1 Inactive 3 GATE0 Timer 0 Gate Control. 0: Timer 0 enabled when TR0 = 1 irrespective of INT0 logic level. 1: Timer 0 enabled only when TR0 = 1 AND INT0 is active as defined by bit IN0PL in register IT01CF (see SFR Definition 14.7). 2 C/T0 Counter/Timer 0 Select. 0: Timer: Timer 0 incremented by clock defined by T0M bit in register CKCON. 1: Counter: Timer 0 incremented by high-to-low transitions on external pin (T0). 1:0 T0M[1:0] Timer 0 Mode Select. These bits select the Timer 0 operation mode. 00: Mode 0, 13-bit Counter/Timer 01: Mode 1, 16-bit Counter/Timer 10: Mode 2, 8-bit Counter/Timer with Auto-Reload 11: Mode 3, Two 8-bit Counter/Timers 272 Rev. 1.2

C8051F50x/F51x SFR Definition 26.4. TL0: Timer 0 Low Byte Bit 7 6 5 4 3 2 1 0 Name TL0[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x8A; SFR Page = All Pages Bit Name Function 7:0 TL0[7:0] Timer 0 Low Byte. The TL0 register is the low byte of the 16-bit Timer 0. SFR Definition 26.5. TL1: Timer 1 Low Byte Bit 7 6 5 4 3 2 1 0 Name TL1[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x8B; SFR Page = All Pages Bit Name Function 7:0 TL1[7:0] Timer 1 Low Byte. The TL1 register is the low byte of the 16-bit Timer 1. Rev. 1.2 273

C8051F50x/F51x SFR Definition 26.6. TH0: Timer 0 High Byte Bit 7 6 5 4 3 2 1 0 Name TH0[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x8C; SFR Page = All Pages Bit Name Function 7:0 TH0[7:0] Timer 0 High Byte. The TH0 register is the high byte of the 16-bit Timer 0. SFR Definition 26.7. TH1: Timer 1 High Byte Bit 7 6 5 4 3 2 1 0 Name TH1[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x8D; SFR Page = All Pages Bit Name Function 7:0 TH1[7:0] Timer 1 High Byte. The TH1 register is the high byte of the 16-bit Timer 1. 274 Rev. 1.2

C8051F50x/F51x 26.2. Timer 2 Timer 2 is a 16-bit timer formed by two 8-bit SFRs: TMR2L (low byte) and TMR2H (high byte). Timer 2 may operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T2SPLIT bit (TMR2CN.3) defines the Timer 2 operation mode. Timer 2 may be clocked by the system clock, the system clock divided by 12, or the external oscillator source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the internal oscillator drives the system clock while Timer 2 (and/or the PCA) is clocked by an external preci- sion oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock. 26.2.1. 16-bit Timer with Auto-Reload When T2SPLIT (TMR2CN.3) is zero, Timer 2 operates as a 16-bit timer with auto-reload. Timer 2 can be clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the 16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 2 reload registers (TMR2RLH and TMR2RLL) is loaded into the Timer 2 register as shown in Figure 26.4, and the Timer 2 High Byte Overflow Flag (TMR2CN.7) is set. If Timer 2 interrupts are enabled (if IE.5 is set), an interrupt will be generated on each Timer 2 overflow. Additionally, if Timer 2 interrupts are enabled and the TF2LEN bit is set (TMR2CN.5), an interrupt will be generated each time the lower 8 bits (TMR2L) overflow from 0xFF to 0x00. CKCON TTTTTTSS 332210CC T2XCLK MMMMMMAA HLHL 10 To ADC, SYSCLK / 12 0 TL2 To SMBus SMBus Overflow 0 External Clock / 8 1 TR2 TCLK TMR2L TMR2H TTFF22HL Interrupt CN TF2LEN SYSCLK 1 2 TF2CEN R T2SPLIT M TR2 T T2XCLK TMR2RLL TMR2RLH Reload Figure 26.4. Timer 2 16-Bit Mode Block Diagram 26.2.2. 8-bit Timers with Auto-Reload When T2SPLIT is set, Timer 2 operates as two 8-bit timers (TMR2H and TMR2L). Both 8-bit timers oper- ate in auto-reload mode as shown in Figure 26.5. TMR2RLL holds the reload value for TMR2L; TMR2RLH holds the reload value for TMR2H. The TR2 bit in TMR2CN handles the run control for TMR2H. TMR2L is always running when configured for 8-bit Mode. Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. The Timer 2 Clock Select bits (T2MH and T2ML in CKCON) select either SYSCLK or the clock defined by the Timer 2 External Clock Select bit (T2XCLK in TMR2CN), as follows: Rev. 1.2 275

C8051F50x/F51x T2MH T2XCLK TMR2H Clock Source T2ML T2XCLK TMR2L Clock Source 0 0 SYSCLK/12 0 0 SYSCLK/12 0 1 External Clock/8 0 1 External Clock/8 1 X SYSCLK 1 X SYSCLK The TF2H bit is set when TMR2H overflows from 0xFF to 0x00; the TF2L bit is set when TMR2L overflows from 0xFF to 0x00. When Timer 2 interrupts are enabled (IE.5), an interrupt is generated each time TMR2H overflows. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an interrupt is gener- ated each time either TMR2L or TMR2H overflows. When TF2LEN is enabled, software must check the TF2H and TF2L flags to determine the source of the Timer 2 interrupt. The TF2H and TF2L interrupt flags are not cleared by hardware and must be manually cleared by software. CKCON TTTTTTSS T2XCLK 332210CC MMMMMMAA Reload HLHL 10 TMR2RLH To SMBus SYSCLK / 12 0 0 External Clock / 8 1 TCLK TR2 TMR2H TF2H Interrupt TF2L 1 TF2LEN N TF2CEN C T2SPLIT Reload R2 TR2 TMR2RLL M SYSCLK T T2XCLK 1 TCLK TMR2L To ADC, SMBus 0 Figure 26.5. Timer 2 8-Bit Mode Block Diagram 26.2.3. External Oscillator Capture Mode Capture Mode allows the external oscillator to be measured against the system clock. Timer 2 can be clocked from the system clock, or the system clock divided by 12, depending on the T2ML (CKCON.4), and T2XCLK bits. When a capture event is generated, the contents of Timer 2 (TMR2H:TMR2L) are loaded into the Timer 2 reload registers (TMR2RLH:TMR2RLL) and the TF2H flag is set. A capture event is generated by the falling edge of the clock source being measured, which is the external oscillator / 8. By recording the difference between two successive timer capture values, the external oscillator frequency can be determined with respect to the Timer 2 clock. The Timer 2 clock should be much faster than the capture clock to achieve an accurate reading. Timer 2 should be in 16-bit auto-reload mode when using Capture Mode. For example, if T2ML = 1b and TF2CEN = 1b, Timer 2 will clock every SYSCLK and capture every external clock divided by 8. If the SYSCLK is 24 MHz and the difference between two successive captures is 5984, then the external clock frequency is as follows: 24 MHz/(5984/8) = 0.032086 MHz or 32.086 kHz This mode allows software to determine the external oscillator frequency when an RC network or capacitor is used to generate the clock source. 276 Rev. 1.2

C8051F50x/F51x CKCON TTTTTTSS 3 3 2 2 1 0CC T2XCLK MMMMMMAA HLHL 1 0 SYSCLK / 12 0 0 TR2 TCLK TMR2L TMR2H External Clock / 8 1 SYSCLK 1 Capture External Clock / 8 TF2CEN TMR2RLL TMR2RLH TF2H Interrupt TF2L N TF2LEN C 2 TF2CEN R T2SPLIT M TR2 T T2XCLK Figure 26.6. Timer 2 External Oscillator Capture Mode Block Diagram Rev. 1.2 277

C8051F50x/F51x SFR Definition 26.8. TMR2CN: Timer 2 Control Bit 7 6 5 4 3 2 1 0 Name TF2H TF2L TF2LEN TF2CEN T2SPLIT TR2 T2XCLK Type R/W R/W R/W R/W R/W R/W R R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xC8; Bit-Addressable; SFR Page = 0x00 Bit Name Function 7 TF2H Timer 2 High Byte Overflow Flag. Set by hardware when the Timer 2 high byte overflows from 0xFF to 0x00. In 16 bit mode, this will occur when Timer 2 overflows from 0xFFFF to 0x0000. When the Timer 2 interrupt is enabled, setting this bit causes the CPU to vector to the Timer 2 interrupt service routine. This bit is not automatically cleared by hardware. 6 TF2L Timer 2 Low Byte Overflow Flag. Set by hardware when the Timer 2 low byte overflows from 0xFF to 0x00. TF2L will be set when the low byte overflows regardless of the Timer 2 mode. This bit is not automatically cleared by hardware. 5 TF2LEN Timer 2 Low Byte Interrupt Enable. When set to 1, this bit enables Timer 2 Low Byte interrupts. If Timer 2 interrupts are also enabled, an interrupt will be generated when the low byte of Timer 2 overflows. 4 TF2CEN Timer 2 Capture Mode Enable. 0: Timer 2 Capture Mode is disabled. 1: Timer 2 Capture Mode is enabled. 3 T2SPLIT Timer 2 Split Mode Enable. When this bit is set, Timer 2 operates as two 8-bit timers with auto-reload. 0: Timer 2 operates in 16-bit auto-reload mode. 1: Timer 2 operates as two 8-bit auto-reload timers. 2 TR2 Timer 2 Run Control. Timer 2 is enabled by setting this bit to 1. In 8-bit mode, this bit enables/disables TMR2H only; TMR2L is always enabled in split mode. 1 Unused Read = 0b; Write = Don’t Care 0 T2XCLK Timer 2 External Clock Select. This bit selects the external clock source for Timer 2. If Timer 2 is in 8-bit mode, this bit selects the external oscillator clock source for both timer bytes. However, the Timer 2 Clock Select bits (T2MH and T2ML in register CKCON) may still be used to select between the external clock and the system clock for either timer. 0: Timer 2 clock is the system clock divided by 12. 1: Timer 2 clock is the external clock divided by 8 (synchronized with SYSCLK). 278 Rev. 1.2

C8051F50x/F51x SFR Definition 26.9. TMR2RLL: Timer 2 Reload Register Low Byte Bit 7 6 5 4 3 2 1 0 Name TMR2RLL[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xCA; SFR Page = 0x00 Bit Name Function 7:0 TMR2RLL[7:0] Timer 2 Reload Register Low Byte. TMR2RLL holds the low byte of the reload value for Timer 2. SFR Definition 26.10. TMR2RLH: Timer 2 Reload Register High Byte Bit 7 6 5 4 3 2 1 0 Name TMR2RLH[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xCB; SFR Page = 0x00 Bit Name Function 7:0 TMR2RLH[7:0] Timer 2 Reload Register High Byte. TMR2RLH holds the high byte of the reload value for Timer 2. Rev. 1.2 279

C8051F50x/F51x SFR Definition 26.11. TMR2L: Timer 2 Low Byte Bit 7 6 5 4 3 2 1 0 Name TMR2L[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xCC; SFR Page = 0x00 Bit Name Function 7:0 TMR2L[7:0] Timer 2 Low Byte. In 16-bit mode, the TMR2L register contains the low byte of the 16-bit Timer 2. In 8- bit mode, TMR2L contains the 8-bit low byte timer value. SFR Definition 26.12. TMR2H Timer 2 High Byte Bit 7 6 5 4 3 2 1 0 Name TMR2H[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xCD; SFR Page = 0x00 Bit Name Function 7:0 TMR2H[7:0] Timer 2 High Byte. In 16-bit mode, the TMR2H register contains the high byte of the 16-bit Timer 2. In 8- bit mode, TMR2H contains the 8-bit high byte timer value. 280 Rev. 1.2

C8051F50x/F51x 26.3. Timer 3 Timer 3 is a 16-bit timer formed by two 8-bit SFRs: TMR3L (low byte) and TMR3H (high byte). Timer 3 may operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T3SPLIT bit (TMR3CN.3) defines the Timer 3 operation mode. Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the internal oscillator drives the system clock while Timer 3 (and/or the PCA) is clocked by an external preci- sion oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock. 26.3.1. 16-bit Timer with Auto-Reload When T3SPLIT (TMR3CN.3) is zero, Timer 3 operates as a 16-bit timer with auto-reload. Timer 3 can be clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the 16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 3 reload registers (TMR3RLH and TMR3RLL) is loaded into the Timer 3 register as shown in Figure 26.7, and the Timer 3 High Byte Overflow Flag (TMR3CN.7) is set. If Timer 3 interrupts are enabled, an interrupt will be generated on each Timer 3 overflow. Additionally, if Timer 3 interrupts are enabled and the TF3LEN bit is set (TMR3CN.5), an interrupt will be generated each time the lower 8 bits (TMR3L) overflow from 0xFF to 0x00. CKCON TTTTTTSS 332210CC T3XCLK MMMMMMAA HLHL 10 To ADC, SYSCLK / 12 0 TL3 To SMBus SMBus Overflow 0 External Clock / 8 1 TR3 TCLK TMR3L TMR3H TTFF33HL Interrupt CN TF3LEN SYSCLK 1 3 TF3CEN R T3SPLIT M TR3 T T3XCLK TMR3RLL TMR3RLH Reload Figure 26.7. Timer 3 16-Bit Mode Block Diagram 26.3.2. 8-bit Timers with Auto-Reload When T3SPLIT is set, Timer 3 operates as two 8-bit timers (TMR3H and TMR3L). Both 8-bit timers oper- ate in auto-reload mode as shown in Figure 26.8. TMR3RLL holds the reload value for TMR3L; TMR3RLH holds the reload value for TMR3H. The TR3 bit in TMR3CN handles the run control for TMR3H. TMR3L is always running when configured for 8-bit Mode. Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. The Timer 3 Clock Select bits (T3MH and T3ML in CKCON) select either SYSCLK or the clock defined by the Timer 3 External Clock Select bit (T3XCLK in TMR3CN), as follows: Rev. 1.2 281

C8051F50x/F51x T3MH T3XCLK TMR3H Clock Source T3ML T3XCLK TMR3L Clock Source 0 0 SYSCLK/12 0 0 SYSCLK/12 0 1 External Clock/8 0 1 External Clock/8 1 X SYSCLK 1 X SYSCLK The TF3H bit is set when TMR3H overflows from 0xFF to 0x00; the TF3L bit is set when TMR3L overflows from 0xFF to 0x00. When Timer 3 interrupts are enabled, an interrupt is generated each time TMR3H over- flows. If Timer 3 interrupts are enabled and TF3LEN (TMR3CN.5) is set, an interrupt is generated each time either TMR3L or TMR3H overflows. When TF3LEN is enabled, software must check the TF3H and TF3L flags to determine the source of the Timer 3 interrupt. The TF3H and TF3L interrupt flags are not cleared by hardware and must be manually cleared by software. CKCON TTTTTTSS T3XCLK 332210CC MMMMMMAA Reload HLHL 10 TMR3RLH To SMBus SYSCLK / 12 0 0 External Clock / 8 1 TCLK TR3 TMR3H TF3H Interrupt TF3L 1 TF3LEN N TF3CEN C T3SPLIT Reload R3 TR3 TMR3RLL M SYSCLK T T3XCLK 1 TCLK TMR3L To ADC, SMBus 0 Figure 26.8. Timer 3 8-Bit Mode Block Diagram 26.3.3. External Oscillator Capture Mode Capture Mode allows the external oscillator to be measured against the system clock. Timer 3 can be clocked from the system clock, or the system clock divided by 12, depending on the T3ML (CKCON.6), and T3XCLK bits. When a capture event is generated, the contents of Timer 3 (TMR3H:TMR3L) are loaded into the Timer 3 reload registers (TMR3RLH:TMR3RLL) and the TF3H flag is set. A capture event is generated by the falling edge of the clock source being measured, which is the external oscillator/8. By recording the difference between two successive timer capture values, the external oscillator frequency can be determined with respect to the Timer 3 clock. The Timer 3 clock should be much faster than the capture clock to achieve an accurate reading. Timer 3 should be in 16-bit auto-reload mode when using Capture Mode. If the SYSCLK is 24 MHz and the difference between two successive captures is 5861, then the external clock frequency is as follows: 24 MHz/(5861/8) = 0.032754 MHz or 32.754 kHz This mode allows software to determine the external oscillator frequency when an RC network or capacitor is used to generate the clock source. 282 Rev. 1.2

C8051F50x/F51x CKCON TTTTTTSS 3 3 2 2 1 0CC T3XCLK MMMMMMAA HLHL 1 0 SYSCLK / 12 0 0 TR3 TCLK TMR3L TMR3H External Clock / 8 1 SYSCLK 1 Capture External Clock / 8 TF3CEN TMR3RLL TMR3RLH TF3H Interrupt TF3L N TF3LEN C 3 TF3CEN R T3SPLIT M TR3 T T3XCLK Figure 26.9. Timer 3 External Oscillator Capture Mode Block Diagram Rev. 1.2 283

C8051F50x/F51x SFR Definition 26.13. TMR3CN: Timer 3 Control Bit 7 6 5 4 3 2 1 0 Name TF3H TF3L TF3LEN TF3CEN T3SPLIT TR3 T3XCLK Type R/W R/W R/W R/W R/W R/W R R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x91; SFR Page = 0x00 Bit Name Function 7 TF3H Timer 3 High Byte Overflow Flag. Set by hardware when the Timer 3 high byte overflows from 0xFF to 0x00. In 16 bit mode, this will occur when Timer 3 overflows from 0xFFFF to 0x0000. When the Timer 3 interrupt is enabled, setting this bit causes the CPU to vector to the Timer 3 interrupt service routine. This bit is not automatically cleared by hardware. 6 TF3L Timer 3 Low Byte Overflow Flag. Set by hardware when the Timer 3 low byte overflows from 0xFF to 0x00. TF3L will be set when the low byte overflows regardless of the Timer 3 mode. This bit is not automatically cleared by hardware. 5 TF3LEN Timer 3 Low Byte Interrupt Enable. When set to 1, this bit enables Timer 3 Low Byte interrupts. If Timer 3 interrupts are also enabled, an interrupt will be generated when the low byte of Timer 3 overflows. 4 TF3CEN Timer 3 Capture Mode Enable. 0: Timer 3 Capture Mode is disabled. 1: Timer 3 Capture Mode is enabled. 3 T3SPLIT Timer 3 Split Mode Enable. When this bit is set, Timer 3 operates as two 8-bit timers with auto-reload. 0: Timer 3 operates in 16-bit auto-reload mode. 1: Timer 3 operates as two 8-bit auto-reload timers. 2 TR3 Timer 3 Run Control. Timer 3 is enabled by setting this bit to 1. In 8-bit mode, this bit enables/disables TMR3H only; TMR3L is always enabled in split mode. 1 Unused Read = 0b; Write = Don’t Care 0 T3XCLK Timer 3 External Clock Select. This bit selects the external clock source for Timer 3. If Timer 3 is in 8-bit mode, this bit selects the external oscillator clock source for both timer bytes. However, the Timer 3 Clock Select bits (T3MH and T3ML in register CKCON) may still be used to select between the external clock and the system clock for either timer. 0: Timer 3 clock is the system clock divided by 12. 1: Timer 3 clock is the external clock divided by 8 (synchronized with SYSCLK). 284 Rev. 1.2

C8051F50x/F51x SFR Definition 26.14. TMR3RLL: Timer 3 Reload Register Low Byte Bit 7 6 5 4 3 2 1 0 Name TMR3RLL[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x92; SFR Page = 0x00 Bit Name Function 7:0 TMR3RLL[7:0] Timer 3 Reload Register Low Byte. TMR3RLL holds the low byte of the reload value for Timer 3. SFR Definition 26.15. TMR3RLH: Timer 3 Reload Register High Byte Bit 7 6 5 4 3 2 1 0 Name TMR3RLH[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x93; SFR Page = 0x00 Bit Name Function 7:0 TMR3RLH[7:0] Timer 3 Reload Register High Byte. TMR3RLH holds the high byte of the reload value for Timer 3. Rev. 1.2 285

C8051F50x/F51x SFR Definition 26.16. TMR3L: Timer 3 Low Byte Bit 7 6 5 4 3 2 1 0 Name TMR3L[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x94; SFR Page = 0x00 Bit Name Function 7:0 TMR3L[7:0] Timer 3 Low Byte. In 16-bit mode, the TMR3L register contains the low byte of the 16-bit Timer 3. In 8- bit mode, TMR3L contains the 8-bit low byte timer value. SFR Definition 26.17. TMR3H Timer 3 High Byte Bit 7 6 5 4 3 2 1 0 Name TMR3H[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0x95; SFR Page = 0x00 Bit Name Function 7:0 TMR3H[7:0] Timer 3 High Byte. In 16-bit mode, the TMR3H register contains the high byte of the 16-bit Timer 3. In 8- bit mode, TMR3H contains the 8-bit high byte timer value. 286 Rev. 1.2

C8051F50x/F51x 27. Programmable Counter Array The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU intervention than the standard 8051 counter/timers. The PCA consists of a dedicated 16-bit counter/timer and six 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line (CEXn) which is routed through the Crossbar to Port I/O when enabled. The counter/timer is driven by a programmable timebase that can select between six sources: system clock, system clock divided by four, system clock divided by twelve, the external oscillator clock source divided by 8, Timer 0 overflows, or an external clock signal on the ECI input pin. Each capture/compare module may be configured to operate independently in one of six modes: Edge-Triggered Capture, Software Timer, High-Speed Output, Fre- quency Output, 8 to 11-Bit PWM, or 16-Bit PWM (each mode is described in Section “27.3. Capture/Compare Modules” on page 289). The external oscillator clock option is ideal for real-time clock (RTC) functionality, allowing the PCA to be clocked by a precision external oscillator while the inter- nal oscillator drives the system clock. The PCA is configured and controlled through the system controller's Special Function Registers. The PCA block diagram is shown in Figure 27.1 Important Note: The PCA Module 5 may be used as a watchdog timer (WDT), and is enabled in this mode following a system reset. Access to certain PCA registers is restricted while WDT mode is enabled. See Section 27.4 for details. SYSCLK/12 SYSCLK/4 Timer 0 Overflow PCA 16-Bit Counter/Timer ECI CLOCK MUX SYSCLK External Clock/8 Capture/Compare Capture/Compare Capture/Compare Capture/Compare Capture/Compare Capture/Compare Module 0 Module 1 Module 2 Module 3 Module 4 Module 5 / WDT E C C C C C C C E E E E E E I X X X X X X 0 1 2 3 4 5 Crossbar Port I/O Figure 27.1. PCA Block Diagram Rev. 1.2 287

C8051F50x/F51x 27.1. PCA Counter/Timer The 16-bit PCA counter/timer consists of two 8-bit SFRs: PCA0L and PCA0H. PCA0H is the high byte (MSB) of the 16-bit counter/timer and PCA0L is the low byte (LSB). Reading PCA0L automatically latches the value of PCA0H into a “snapshot” register; the following PCA0H read accesses this “snapshot” register. Reading the PCA0L Register first guarantees an accurate reading of the entire 16-bit PCA0 counter. Reading PCA0H or PCA0L does not disturb the counter operation. The CPS[2:0] bits in the PCA0MD reg- ister select the timebase for the counter/timer as shown in Table 27.1. When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by soft- ware. Clearing the CIDL bit in the PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle mode. Table 27.1. PCA Timebase Input Options CPS2 CPS1 CPS0 Timebase 0 0 0 System clock divided by 12. 0 0 1 System clock divided by 4. 0 1 0 Timer 0 overflow. 0 1 1 High-to-low transitions on ECI (max rate = system clock divided by 4). 1 0 0 System clock. 1 0 1 External oscillator source divided by 8.* 1 1 x Reserved. *Note: External oscillator source divided by 8 is synchronized with the system clock. IDLE PCA0MD PCA0CN CWW CCCE CCCCCCCC I DD PPPC FRCCCCCC DT L SSSF FFFFFF L EC 21 0 54 3 21 0 To SFR Bus K PCA0L read Snapshot Register SYSCLK/12 000 SYSCLK/4 001 Timer 0 Overflow 010 0 PCA0H PCA0L Overflow To PCA Interrupt System ECI 011 1 SYSCLK CF 100 External Clock/8 101 To PCA Modules Figure 27.2. PCA Counter/Timer Block Diagram 288 Rev. 1.2

C8051F50x/F51x 27.2. PCA0 Interrupt Sources Figure 27.3 shows a diagram of the PCA interrupt tree. There are five independent event flags that can be used to generate a PCA0 interrupt. They are as follows: the main PCA counter overflow flag (CF), which is set upon a 16-bit overflow of the PCA0 counter, an intermediate overflow flag (COVF), which can be set on an overflow from the 8th, 9th, 10th, or 11th bit of the PCA0 counter, and the individual flags for each PCA channel (CCF0, CCF1, CCF2, CCF3, CCF4, and CCF5), which are set according to the operation mode of that module. These event flags are always set when the trigger condition occurs. Each of these flags can be individually selected to generate a PCA0 interrupt, using the corresponding interrupt enable flag (ECF for CF, ECOV for COVF, and ECCFn for each CCFn). PCA0 interrupts must be globally enabled before any individual interrupt sources are recognized by the processor. PCA0 interrupts are globally enabled by set- ting the EA bit and the EPCA0 bit to logic 1. (for n = 0 to 2) PCA0CPMn PCA0CN PCA0MD PCA0PWM PECCMTPE CCCCCCCC CWW CCCE ACE CC WCAAAOWC FRCCCCCC I DD PPPC ROC LL MOPPTGMC FFFFFF DTL SSSF SVO SS 1MPNnn nF 543210 LEC 210 EFV EE 6nnn n K L LL n 10 PCA Counter/Timer 8, 9, Set 8, 9, 10, or 11 bit Operation 10 or 11-bit Overflow PCA Counter/Timer 16- 0 0 bit Overflow 1 ECCF0 1 EPCA0 EA PCA Module 0 0 0 0 Interrupt Priority (CCF0) 1 1 1 Decoder ECCF1 PCA Module 1 0 (CCF1) 1 ECCF2 PCA Module 2 0 (CCF2) 1 ECCF3 PCA Module 3 0 (CCF3) 1 ECCF4 PCA Module 4 0 (CCF4) 1 ECCF5 PCA Module 5 0 (CCF5) 1 Figure 27.3. PCA Interrupt Block Diagram 27.3. Capture/Compare Modules Each module can be configured to operate independently in one of six operation modes: Edge-triggered Capture, Software Timer, High Speed Output, Frequency Output, 8 to 11-Bit Pulse Width Modulator, or 16- Bit Pulse Width Modulator. Each module has Special Function Registers (SFRs) associated with it in the CIP-51 system controller. These registers are used to exchange data with a module and configure the module's mode of operation. Table 27.2 summarizes the bit settings in the PCA0CPMn and PCA0PWM registers used to select the PCA capture/compare module’s operating mode. All modules set to use 8, 9, 10, or 11-bit PWM mode must use the same cycle length (8-11 bits). Setting the ECCFn bit in a PCA0CPMn register enables the module's CCFn interrupt. Rev. 1.2 289

C8051F50x/F51x Table 27.2. PCA0CPM and PCA0PWM Bit Settings for PCA Capture/Compare Modules Operational Mode PCA0CPMn PCA0PWM Bit Number 7 6 5 4 3 2 1 0 7 6 5 4–2 1–0 Capture triggered by positive edge on CEXn X X 1 0 0 0 0 A 0 X B XXX XX Capture triggered by negative edge on CEXn X X 0 1 0 0 0 A 0 X B XXX XX Capture triggered by any transition on CEXn X X 1 1 0 0 0 A 0 X B XXX XX Software Timer X C 0 0 1 0 0 A 0 X B XXX XX High Speed Output X C 0 0 1 1 0 A 0 X B XXX XX Frequency Output X C 0 0 0 1 1 A 0 X B XXX XX 8-Bit Pulse Width Modulator (Note 7) 0 C 0 0 E 0 1 A 0 X B XXX 00 9-Bit Pulse Width Modulator (Note 7) 0 C 0 0 E 0 1 A D X B XXX 01 10-Bit Pulse Width Modulator (Note 7) 0 C 0 0 E 0 1 A D X B XXX 10 11-Bit Pulse Width Modulator (Note 7) 0 C 0 0 E 0 1 A D X B XXX 11 16-Bit Pulse Width Modulator 1 C 0 0 E 0 1 A 0 X B XXX XX Notes: 1. X = Don’t Care (no functional difference for individual module if 1 or 0). 2. A = 1 to enable interrupts for this module (PCA interrupt triggered on CCFn set to 1). 3. B = 1 to enable 8th, 9th, 10th or 11th bit overflow interrupt (Depends on setting of CLSEL[1:0]). 4. C = When set to 0, the digital comparator is off. For high speed and frequency output modes, the associated pin will not toggle. In any of the PWM modes, this generates a 0% duty cycle (output = 0). 5. D = Selects whether the Capture/Compare register (0) or the Auto-Reload register (1) for the associated channel is accessed via addresses PCA0CPHn and PCA0CPLn. 6. E = When set to 1, a match event will cause the CCFn flag for the associated channel to be set. 7. All modules set to 8, 9, 10 or 11-bit PWM mode use the same cycle length setting. 27.3.1. Edge-triggered Capture Mode In this mode, a valid transition on the CEXn pin causes the PCA to capture the value of the PCA counter/timer and load it into the corresponding module's 16-bit capture/compare register (PCA0CPLn and PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn register are used to select the type of transi- tion that triggers the capture: low-to-high transition (positive edge), high-to-low transition (negative edge), or either transition (positive or negative edge). When a capture occurs, the Capture/Compare Flag (CCFn) in PCA0CN is set to logic 1. An interrupt request is generated if the CCFn interrupt for that module is enabled. The CCFn bit is not automatically cleared by hardware when the CPU vectors to the interrupt ser- vice routine, and must be cleared by software. If both CAPPn and CAPNn bits are set to logic 1, then the state of the Port pin associated with CEXn can be read directly to determine whether a rising-edge or fall- ing-edge caused the capture. 290 Rev. 1.2

C8051F50x/F51x PCA Interrupt PCA0CPMn PCA0CN PECCMTPE WCAAAOWC CCCCCCCC MOPPTGMC FRCCCCCC 1MPNn n n F FFFFFF 6 n n n n 5 4 3 2 1 0 n x x 0 0 0 x Fn) PCA0CPLn PCA0CPHn C C 0 o (t 1 CEXn Capture Port I/O Crossbar 0 1 PCA PCA0L PCA0H Timebase Figure 27.4. PCA Capture Mode Diagram Note: The CEXn input signal must remain high or low for at least 2 system clock cycles to be recognized by the hardware. 27.3.2. Software Timer (Compare) Mode In Software Timer mode, the PCA counter/timer value is compared to the module's 16-bit capture/compare register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in PCA0CN is set to logic 1. An interrupt request is generated if the CCFn interrupt for that module is enabled. The CCFn bit is not automatically cleared by hardware when the CPU vectors to the interrupt ser- vice routine, and must be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn regis- ter enables Software Timer mode. Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap- ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1. Rev. 1.2 291

C8051F50x/F51x Write to PCA0CPLn 0 Reset ENB Write to PCA0CPHn ENB PCA Interrupt 1 PCA0CPMn PECCMTPE PCA0CN WCAAAOWC CCCCCCCC MOPPTGMC PCA0CPLn PCA0CPHn FRCCCCCC 1MPNnn n F FFFFFF 6 nnn n 210210 n x 0 0 0 0 x 0 Enable 16-bit Comparator Match 1 PCA PCA0L PCA0H Timebase Figure 27.5. PCA Software Timer Mode Diagram 27.3.3. High-Speed Output Mode In High-Speed Output mode, a module’s associated CEXn pin is toggled each time a match occurs between the PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in PCA0CN is set to logic 1. An interrupt request is generated if the CCFn interrupt for that module is enabled. The CCFn bit is not auto- matically cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by software. Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the High- Speed Output mode. If ECOMn is cleared, the associated pin will retain its state, and not toggle on the next match event. Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap- ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1. 292 Rev. 1.2

C8051F50x/F51x Write to PCA0CPLn 0 ENB Reset PCA0CPMn Write to PCA0CPHn ENB PECCMTPE 1 WCAAAOWC MOPPTGMC 1MPNn n n F 6 n n n n n x 0 0 0 x PCA Interrupt PCA0CN CCCCCCCC PCA0CPLn PCA0CPHn FRCCCCCC FFFFFF 5 4 3 2 1 0 0 Enable Match 16-bit Comparator 1 TOGn Toggle 0 CEXn Crossbar Port I/O 1 PCA PCA0L PCA0H Timebase Figure 27.6. PCA High-Speed Output Mode Diagram 27.3.4. Frequency Output Mode Frequency Output Mode produces a programmable-frequency square wave on the module’s associated CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count before the out- put is toggled. The frequency of the square wave is then defined by Equation 27.1. F F = -------------------P---C----A----------------- CEXn 2×PCA0CPHn Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation. Equation 27.1. Square Wave Frequency Output Where F is the frequency of the clock selected by the CPS[2:0] bits in the PCA mode register, PCA PCA0MD. The lower byte of the capture/compare module is compared to the PCA counter low byte; on a match, CEXn is toggled and the offset held in the high byte is added to the matched value in PCA0CPLn. Frequency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn reg- ister. Note that the MATn bit should normally be set to 0 in this mode. If the MATn bit is set to 1, the CCFn flag for the channel will be set when the 16-bit PCA0 counter and the 16-bit capture/compare register for the channel are equal. Rev. 1.2 293

C8051F50x/F51x Write to PCA0CPLn 0 Reset ENB PCA0CPMn Write to PECCMTPE PCA0CPHn ENB WCAAAOWC PCA0CPLn 8-bit Adder PCA0CPHn 1 MOPPTGMC 1MPNnn nF Adder 6 nnn n Enable n TOGn x 0 0 0 x Toggle Enable 8-bit match 0 CEXn Crossbar Port I/O Comparator 1 PCA Timebase PCA0L Figure 27.7. PCA Frequency Output Mode 27.3.5. 8-bit, 9-bit, 10-bit and 11-bit Pulse Width Modulator Modes Each module can be used independently to generate a pulse width modulated (PWM) output on its associ- ated CEXn pin. The frequency of the output is dependent on the timebase for the PCA counter/timer, and the setting of the PWM cycle length (8, 9, 10 or 11-bits). For backwards-compatibility with the 8-bit PWM mode available on other devices, the 8-bit PWM mode operates slightly different than 9, 10 and 11-bit PWM modes. It is important to note that all channels configured for 8/9/10/11-bit PWM mode will use the same cycle length. It is not possible to configure one channel for 8-bit PWM mode and another for 11- bit mode (for example). However, other PCA channels can be configured to Pin Capture, High-Speed Out- put, Software Timer, Frequency Output, or 16-bit PWM mode independently. 27.3.5.1. 8-bit Pulse Width Modulator Mode The duty cycle of the PWM output signal in 8-bit PWM mode is varied using the module's PCA0CPLn cap- ture/compare register. When the value in the low byte of the PCA counter/timer (PCA0L) is equal to the value in PCA0CPLn, the output on the CEXn pin will be set. When the count value in PCA0L overflows, the CEXn output will be reset (see Figure 27.8). Also, when the counter/timer low byte (PCA0L) overflows from 0xFF to 0x00, PCA0CPLn is reloaded automatically with the value stored in the module’s capture/compare high byte (PCA0CPHn) without software intervention. Setting the ECOMn and PWMn bits in the PCA0CPMn register, and setting the CLSEL bits in register PCA0PWM to 00b enables 8-Bit Pulse Width Modulator mode. If the MATn bit is set to 1, the CCFn flag for the module will be set each time an 8-bit comparator match (rising edge) occurs. The COVF flag in PCA0PWM can be used to detect the overflow (falling edge), which will occur every 256 PCA clock cycles. The duty cycle for 8-Bit PWM Mode is given in Equation 27.2. Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap- ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1. (256–PCA0CPHn) Duty Cycle = ------------------------------------------------------- 256 Equation 27.2. 8-Bit PWM Duty Cycle Using Equation 27.2, the largest duty cycle is 100% (PCA0CPHn = 0), and the smallest duty cycle is 0.39% (PCA0CPHn = 0xFF). A 0% duty cycle may be generated by clearing the ECOMn bit to 0. 294 Rev. 1.2

C8051F50x/F51x Write to PCA0CPLn 0 Reset ENB PCA0CPHn Write to PCA0CPHn ENB 1 COVF PCA0PWM PCA0CPMn AEC CC PECCMTPE RCO L L WCAAAOWC PCA0CPLn SOV SS MOPPTGMC EVF EE 1MPNnn n F L L L 6 nnn n 1 0 n 0 x 0 0 0 0 0 x 0 x Enable 8-bit match S SET Q CEXn Crossbar Port I/O Comparator R CLR Q PCA Timebase PCA0L Overflow Figure 27.8. PCA 8-Bit PWM Mode Diagram 27.3.5.2. 9/10/11-bit Pulse Width Modulator Mode The duty cycle of the PWM output signal in 9/10/11-bit PWM mode should be varied by writing to an “Auto- Reload” Register, which is dual-mapped into the PCA0CPHn and PCA0CPLn register locations. The data written to define the duty cycle should be right-justified in the registers. The auto-reload registers are accessed (read or written) when the bit ARSEL in PCA0PWM is set to 1. The capture/compare registers are accessed when ARSEL is set to 0. When the least-significant N bits of the PCA0 counter match the value in the associated module’s cap- ture/compare register (PCA0CPn), the output on CEXn is asserted high. When the counter overflows from the Nth bit, CEXn is asserted low (see Figure 27.9). Upon an overflow from the Nth bit, the COVF flag is set, and the value stored in the module’s auto-reload register is loaded into the capture/compare register. The value of N is determined by the CLSEL bits in register PCA0PWM. The 9, 10 or 11-bit PWM mode is selected by setting the ECOMn and PWMn bits in the PCA0CPMn regis- ter, and setting the CLSEL bits in register PCA0PWM to the desired cycle length (other than 8-bits). If the MATn bit is set to 1, the CCFn flag for the module will be set each time a comparator match (rising edge) occurs. The COVF flag in PCA0PWM can be used to detect the overflow (falling edge), which will occur every 512 (9-bit), 1024 (10-bit) or 2048 (11-bit) PCA clock cycles. The duty cycle for 9/10/11-Bit PWM Mode is given in Equation 27.2, where N is the number of bits in the PWM cycle. Important Note About PCA0CPHn and PCA0CPLn Registers: When writing a 16-bit value to the PCA0CPn registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1. (2N–PCA0CPn) Duty Cycle = ------------------------------------------------ N 2 Equation 27.3. 9, 10, and 11-Bit PWM Duty Cycle A 0% duty cycle may be generated by clearing the ECOMn bit to 0. Rev. 1.2 295

C8051F50x/F51x Write to PCA0CPLn 0 R/W when Reset ENB ARSEL = 1 P(CAuAto0-CRePloHa:dL)n PCA0PWM AEC CC Write to (right-justified) RCO L L PCA0CPHn ENB SOV SS 1 EVF EE L L L PCA0CPMn 1 0 PECCMTPE R/W when x WCAAAOWC ARSEL = 0 (Capture/Compare) Set “N” bits: MOPPTGMC PCA0CPH:Ln 01 = 9 bits 1MPNnn nF (right-justified) 10 = 10 bits 6 nnn n 11 = 11 bits n 0 0 0 x 0 x Enable N-bit Comparator match S SET Q CEXn Crossbar Port I/O R CLR Q PCA Timebase PCA0H:L Overflow of Nth Bit Figure 27.9. PCA 9, 10 and 11-Bit PWM Mode Diagram 27.3.6. 16-Bit Pulse Width Modulator Mode A PCA module may also be operated in 16-Bit PWM mode. 16-bit PWM mode is independent of the other (8/9/10/11-bit) PWM modes. In this mode, the 16-bit capture/compare module defines the number of PCA clocks for the low time of the PWM signal. When the PCA counter matches the module contents, the out- put on CEXn is asserted high; when the 16-bit counter overflows, CEXn is asserted low. To output a vary- ing duty cycle, new value writes should be synchronized with PCA CCFn match interrupts. 16-Bit PWM Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn register. For a vary- ing duty cycle, match interrupts should be enabled (ECCFn = 1 AND MATn = 1) to help synchronize the capture/compare register writes. If the MATn bit is set to 1, the CCFn flag for the module will be set each time a 16-bit comparator match (rising edge) occurs. The CF flag in PCA0CN can be used to detect the overflow (falling edge). The duty cycle for 16-Bit PWM Mode is given by Equation 27.4. Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Cap- ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1. (65536–PCA0CPn) Duty Cycle = --------------------------------------------------------- 65536 Equation 27.4. 16-Bit PWM Duty Cycle Using Equation 27.4, the largest duty cycle is 100% (PCA0CPn = 0), and the smallest duty cycle is 0.0015% (PCA0CPn = 0xFFFF). A 0% duty cycle may be generated by clearing the ECOMn bit to 0. 296 Rev. 1.2

C8051F50x/F51x Write to PCA0CPLn 0 Reset ENB Write to PCA0CPHn ENB 1 PCA0CPMn PECCMTPE WCAAAOWC PCA0CPHn PCA0CPLn MOPPTGMC 1MPNnnnF 6nnn n n 1 00x0 x Enable 16-bit Comparator match S SET Q CEXn Crossbar Port I/O R CLR Q PCA Timebase PCA0H PCA0L Overflow Figure 27.10. PCA 16-Bit PWM Mode 27.4. Watchdog Timer Mode A programmable watchdog timer (WDT) function is available through the PCA Module 5. The WDT is used to generate a reset if the time between writes to the WDT update register (PCA0CPH5) exceed a specified limit. The WDT can be configured and enabled/disabled as needed by software. With the WDTE bit set in the PCA0MD register, Module 5 operates as a watchdog timer (WDT). The Mod- ule 5 high byte is compared to the PCA counter high byte; the Module 5 low byte holds the offset to be used when WDT updates are performed. The Watchdog Timer is enabled on reset. Writes to some PCA registers are restricted while the Watchdog Timer is enabled. The WDT will generate a reset shortly after code begins execution. To avoid this reset, the WDT should be explicitly disabled (and option- ally re-configured and re-enabled if it is used in the system). 27.4.1. Watchdog Timer Operation While the WDT is enabled:  PCA counter is forced on.  Writes to PCA0L and PCA0H are not allowed.  PCA clock source bits (CPS[2:0]) are frozen.  PCA Idle control bit (CIDL) is frozen.  Module 5 is forced into software timer mode.  Writes to the Module 5 mode register (PCA0CPM5) are disabled. While the WDT is enabled, writes to the CR bit will not change the PCA counter state; the counter will run until the WDT is disabled. The PCA counter run control bit (CR) will read zero if the WDT is enabled but user software has not enabled the PCA counter. If a match occurs between PCA0CPH5 and PCA0H while the WDT is enabled, a reset will be generated. To prevent a WDT reset, the WDT may be updated with a write of any value to PCA0CPH5. Upon a PCA0CPH5 write, PCA0H plus the offset held in PCA0CPL5 is loaded into PCA0CPH5 (See Figure 27.11). Rev. 1.2 297

C8051F50x/F51x PCA0MD CWW CCCE PCA0CPH5 I D D PPPC D T L SSSF L E C 2 1 0 K 8-bit Match Reset Comparator Enable PCA0L Overflow PCA0CPL5 8-bit Adder PCA0H Adder Enable Write to PCA0CPH2 Figure 27.11. PCA Module 2 with Watchdog Timer Enabled Note that the 8-bit offset held in PCA0CPH5 is compared to the upper byte of the 16-bit PCA counter. This offset value is the number of PCA0L overflows before a reset. Up to 256 PCA clocks may pass before the first PCA0L overflow occurs, depending on the value of the PCA0L when the update is performed. The total offset is then given (in PCA clocks) by Equation 27.5, where PCA0L is the value of the PCA0L register at the time of the update. Offset = (256 x PCA0CPL5)+(256–PCA0L) Equation 27.5. Watchdog Timer Offset in PCA Clocks The WDT reset is generated when PCA0L overflows while there is a match between PCA0CPH5 and PCA0H. Software may force a WDT reset by writing a 1 to the CCF5 flag (PCA0CN.5) while the WDT is enabled. 27.4.2. Watchdog Timer Usage To configure the WDT, perform the following tasks:  Disable the WDT by writing a 0 to the WDTE bit.  Select the desired PCA clock source (with the CPS[2:0] bits).  Load PCA0CPL5 with the desired WDT update offset value.  Configure the PCA Idle mode (set CIDL if the WDT should be suspended while the CPU is in Idle mode).  Enable the WDT by setting the WDTE bit to 1.  Reset the WDT timer by writing to PCA0CPH5. The PCA clock source and Idle mode select cannot be changed while the WDT is enabled. The watchdog timer is enabled by setting the WDTE or WDLCK bits in the PCA0MD register. When WDLCK is set, the WDT cannot be disabled until the next system reset. If WDLCK is not set, the WDT is disabled by clearing the WDTE bit. The WDT is enabled following any reset. The PCA0 counter clock defaults to the system clock divided by 12, PCA0L defaults to 0x00, and PCA0CPL5 defaults to 0x00. Using Equation 27.5, this results in a WDT timeout interval of 256 PCA clock cycles, or 3072 system clock cycles. Table 27.3 lists some example tim- eout intervals for typical system clocks. 298 Rev. 1.2

C8051F50x/F51x Table 27.3. Watchdog Timer Timeout Intervals1 System Clock (Hz) PCA0CPL5 Timeout Interval (ms) 24,000,000 255 32.8 24,000,000 128 16.5 24,000,000 32 4.2 3,000,000 255 262.1 3,000,000 128 132.1 3,000,000 32 33.8 187,5002 255 4194 187,5002 128 2114 187,5002 32 541 Notes: 1. Assumes SYSCLK/12 as the PCA clock source, and a PCA0L value of 0x00 at the update time. 2. Internal SYSCLK reset frequency = Internal Oscillator divided by 128. Rev. 1.2 299

C8051F50x/F51x 27.5. Register Descriptions for PCA0 Following are detailed descriptions of the special function registers related to the operation of the PCA. SFR Definition 27.1. PCA0CN: PCA Control Bit 7 6 5 4 3 2 1 0 Name CF CR CCF5 CCF4 CCF3 CCF2 CCF1 CCF0 Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD8; Bit-Addressable; SFR Page = 0x00 Bit Name Function 7 CF PCA Counter/Timer Overflow Flag. Set by hardware when the PCA Counter/Timer overflows from 0xFFFF to 0x0000. When the Counter/Timer Overflow (CF) interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This bit is not automatically cleared by hardware and must be cleared by software. 6 CR PCA Counter/Timer Run Control. This bit enables/disables the PCA Counter/Timer. 0: PCA Counter/Timer disabled. 1: PCA Counter/Timer enabled. 5 CCF5 PCA Module 5 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF5 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou- tine. This bit is not automatically cleared by hardware and must be cleared by software. 4 CCF4 PCA Module 4 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF4 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou- tine. This bit is not automatically cleared by hardware and must be cleared by software. 3 CCF3 PCA Module 3 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF3 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou- tine. This bit is not automatically cleared by hardware and must be cleared by software. 2 CCF2 PCA Module 2 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF2 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou- tine. This bit is not automatically cleared by hardware and must be cleared by software. 1 CCF1 PCA Module 1 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF1 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou- tine. This bit is not automatically cleared by hardware and must be cleared by software. 0 CCF0 PCA Module 0 Capture/Compare Flag. This bit is set by hardware when a match or capture occurs. When the CCF0 interrupt is enabled, setting this bit causes the CPU to vector to the PCA interrupt service rou- tine. This bit is not automatically cleared by hardware and must be cleared by software. 300 Rev. 1.2

C8051F50x/F51x SFR Definition 27.2. PCA0MD: PCA Mode Bit 7 6 5 4 3 2 1 0 Name CIDL WDTE WDLCK CPS[2:0] ECF Type R/W R/W R/W R R/W R/W R/W R/W Reset 0 1 0 0 0 0 0 0 SFR Address = 0xD9; SFR Page = 0x00 Bit Name Function 7 CIDL PCA Counter/Timer Idle Control. Specifies PCA behavior when CPU is in Idle Mode. 0: PCA continues to function normally while the system controller is in Idle Mode. 1: PCA operation is suspended while the system controller is in Idle Mode. 6 WDTE Watchdog Timer Enable If this bit is set, PCA Module 5 is used as the watchdog timer. 0: Watchdog Timer disabled. 1: PCA Module 5 enabled as Watchdog Timer. 5 WDLCK Watchdog Timer Lock This bit locks/unlocks the Watchdog Timer Enable. When WDLCK is set, the Watchdog Timer may not be disabled until the next system reset. 0: Watchdog Timer Enable unlocked. 1: Watchdog Timer Enable locked. 4 Unused Read = 0b, Write = Don't care. 3:1 CPS[2:0] PCA Counter/Timer Pulse Select. These bits select the timebase source for the PCA counter 000: System clock divided by 12 001: System clock divided by 4 010: Timer 0 overflow 011: High-to-low transitions on ECI (max rate = system clock divided by 4) 100: System clock 101: External clock divided by 8 (synchronized with the system clock) 11x: Reserved 0 ECF PCA Counter/Timer Overflow Interrupt Enable. This bit sets the masking of the PCA Counter/Timer Overflow (CF) interrupt. 0: Disable the CF interrupt. 1: Enable a PCA Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is set. Note: When the WDTE bit is set to 1, the other bits in the PCA0MD register cannot be modified. To change the contents of the PCA0MD register, the Watchdog Timer must first be disabled. Rev. 1.2 301

C8051F50x/F51x SFR Definition 27.3. PCA0PWM: PCA PWM Configuration Bit 7 6 5 4 3 2 1 0 Name ARSEL ECOV COVF CLSEL[1:0] Type R/W R/W R/W R R R R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xD9; SFR Page = 0x0F Bit Name Function 7 ARSEL Auto-Reload Register Select. This bit selects whether to read and write the normal PCA capture/compare registers (PCA0CPn), or the Auto-Reload registers at the same SFR addresses. This function is used to define the reload value for 9, 10, and 11-bit PWM modes. In all other modes, the Auto-Reload registers have no function. 0: Read/Write Capture/Compare Registers at PCA0CPHn and PCA0CPLn. 1: Read/Write Auto-Reload Registers at PCA0CPHn and PCA0CPLn. 6 ECOV Cycle Overflow Interrupt Enable. This bit sets the masking of the Cycle Overflow Flag (COVF) interrupt. 0: COVF will not generate PCA interrupts. 1: A PCA interrupt will be generated when COVF is set. 5 COVF Cycle Overflow Flag. This bit indicates an overflow of the 8th, 9th, 10th, or 11th bit of the main PCA counter (PCA0). The specific bit used for this flag depends on the setting of the Cycle Length Select bits. The bit can be set by hardware or software, but must be cleared by soft- ware. 0: No overflow has occurred since the last time this bit was cleared. 1: An overflow has occurred since the last time this bit was cleared. 4:2 Unused Read = 000b; Write = Don’t care. 1:0 CLSEL[1:0] Cycle Length Select. When 16-bit PWM mode is not selected, these bits select the length of the PWM cycle, between 8, 9, 10, or 11 bits. This affects all channels configured for PWM which are not using 16-bit PWM mode. These bits are ignored for individual channels config- ured to16-bit PWM mode. 00: 8 bits. 01: 9 bits. 10: 10 bits. 11: 11 bits. 302 Rev. 1.2

C8051F50x/F51x SFR Definition 27.4. PCA0CPMn: PCA Capture/Compare Mode Bit 7 6 5 4 3 2 1 0 Name PWM16n ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Addresses: PCA0CPM0 = 0xDA, PCA0CPM1 = 0xDB, PCA0CPM2 = 0xDC; PCA0CPM3 = 0xDD, PCA0CPM4 = 0xDE, PCA0CPM5 = 0xDF, SFR Page (all registers) = 0x00 Bit Name Function 7 PWM16n 16-bit Pulse Width Modulation Enable. This bit enables 16-bit mode when Pulse Width Modulation mode is enabled. 0: 8 to 11-bit PWM selected. 1: 16-bit PWM selected. 6 ECOMn Comparator Function Enable. This bit enables the comparator function for PCA module n when set to 1. 5 CAPPn Capture Positive Function Enable. This bit enables the positive edge capture for PCA module n when set to 1. 4 CAPNn Capture Negative Function Enable. This bit enables the negative edge capture for PCA module n when set to 1. 3 MATn Match Function Enable. This bit enables the match function for PCA module n when set to 1. When enabled, matches of the PCA counter with a module's capture/compare register cause the CCFn bit in PCA0MD register to be set to logic 1. 2 TOGn Toggle Function Enable. This bit enables the toggle function for PCA module n when set to 1. When enabled, matches of the PCA counter with a module's capture/compare register cause the logic level on the CEXn pin to toggle. If the PWMn bit is also set to logic 1, the module oper- ates in Frequency Output Mode. 1 PWMn Pulse Width Modulation Mode Enable. This bit enables the PWM function for PCA module n when set to 1. When enabled, a pulse width modulated signal is output on the CEXn pin. 8 to 11-bit PWM is used if PWM16n is cleared; 16-bit mode is used if PWM16n is set to logic 1. If the TOGn bit is also set, the module operates in Frequency Output Mode. 0 ECCFn Capture/Compare Flag Interrupt Enable. This bit sets the masking of the Capture/Compare Flag (CCFn) interrupt. 0: Disable CCFn interrupts. 1: Enable a Capture/Compare Flag interrupt request when CCFn is set. Note: When the WDTE bit is set to 1, the PCA0CPM5 register cannot be modified, and module 5 acts as the watchdog timer. To change the contents of the PCA0CPM5 register or the function of module 5, the Watchdog Timer must be disabled. Rev. 1.2 303

C8051F50x/F51x SFR Definition 27.5. PCA0L: PCA Counter/Timer Low Byte Bit 7 6 5 4 3 2 1 0 Name PCA0[7:0] Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xF9; SFR Page = 0x00 Bit Name Function 7:0 PCA0[7:0] PCA Counter/Timer Low Byte. The PCA0L register holds the low byte (LSB) of the 16-bit PCA Counter/Timer. Note: When the WDTE bit is set to 1, the PCA0L register cannot be modified by software. To change the contents of the PCA0L register, the Watchdog Timer must first be disabled. SFR Definition 27.6. PCA0H: PCA Counter/Timer High Byte Bit 7 6 5 4 3 2 1 0 Name PCA0[15:8] Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Address = 0xFA; SFR Page = 0x00 Bit Name Function 7:0 PCA0[15:8] PCA Counter/Timer High Byte. The PCA0H register holds the high byte (MSB) of the 16-bit PCA Counter/Timer. Reads of this register will read the contents of a “snapshot” register, whose contents are updated only when the contents of PCA0L are read (see Section 27.1). Note: When the WDTE bit is set to 1, the PCA0H register cannot be modified by software. To change the contents of the PCA0H register, the Watchdog Timer must first be disabled. 304 Rev. 1.2

C8051F50x/F51x SFR Definition 27.7. PCA0CPLn: PCA Capture Module Low Byte Bit 7 6 5 4 3 2 1 0 Name PCA0CPn[7:0] Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Addresses: PCA0CPL0 = 0xFB, PCA0CPL1 = 0xE9, PCA0CPL2 = 0xEB, PCA0CPL3 = 0xED, PCA0CPL4 = 0xFD, PCA0CPL5 = 0xCE; SFR Page (all registers) = 0x00 Bit Name Function 7:0 PCA0CPn[7:0] PCA Capture Module Low Byte. The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n. This register address also allows access to the low byte of the corresponding PCA channel’s auto-reload value for 9, 10, or 11-bit PWM mode. The ARSEL bit in register PCA0PWM controls which register is accessed. Note: A write to this register will clear the module’s ECOMn bit to a 0. SFR Definition 27.8. PCA0CPHn: PCA Capture Module High Byte Bit 7 6 5 4 3 2 1 0 Name PCA0CPn[15:8] Type R/W R/W R/W R/W R/W R/W R/W R/W Reset 0 0 0 0 0 0 0 0 SFR Addresses: PCA0CPH0 = 0xFC, PCA0CPH1 = 0xEA, PCA0CPH2 = 0xEC, PCA0CPH3 = 0xEE, PCA0CPH4 = 0xFE, PCA0CPH5 = 0xCF; SFR Page (all registers) = 0x00 Bit Name Function 7:0 PCA0CPn[15:8] PCA Capture Module High Byte. The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n. This register address also allows access to the high byte of the corresponding PCA channel’s auto-reload value for 9, 10, or 11-bit PWM mode. The ARSEL bit in register PCA0PWM controls which register is accessed. Note: A write to this register will set the module’s ECOMn bit to a 1. Rev. 1.2 305

C8051F50x/F51x 28. C2 Interface C8051F50x/F51x devices include an on-chip Silicon Labs 2-Wire (C2) debug interface to allow Flash pro- gramming and in-system debugging with the production part installed in the end application. The C2 inter- face uses a clock signal (C2CK) and a bi-directional C2 data signal (C2D) to transfer information between the device and a host system. See the C2 Interface Specification for details on the C2 protocol. 28.1. C2 Interface Registers The following describes the C2 registers necessary to perform Flash programming through the C2 inter- face. All C2 registers are accessed through the C2 interface as described in the C2 Interface Specification. C2 Register Definition 28.1. C2ADD: C2 Address Bit 7 6 5 4 3 2 1 0 Name C2ADD[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 Bit Name Function 7:0 C2ADD[7:0] C2 Address. The C2ADD register is accessed via the C2 interface to select the target Data register for C2 Data Read and Data Write commands. Address Description 0x00 Selects the Device ID register for Data Read instructions 0x01 Selects the Revision ID register for Data Read instructions 0x02 Selects the C2 Flash Programming Control register for Data Read/Write instructions 0xB4 Selects the C2 Flash Programming Data register for Data Read/Write instructions Rev. 1.2 306

C8051F50x/F51x C2 Register Definition 28.2. DEVICEID: C2 Device ID Bit 7 6 5 4 3 2 1 0 Name DEVICEID[7:0] Type R/W Reset 0 0 0 1 0 1 0 0 C2 Address: 0xFD; SFR Address = 0xFD; SFR Page = 0x0F Bit Name Function 7:0 DEVICEID[7:0] Device ID. This read-only register returns the 8-bit device ID: 0x1C (C8051F50x/F51x). C2 Register Definition 28.3. REVID: C2 Revision ID Bit 7 6 5 4 3 2 1 0 Name REVID[7:0] Type R/W Reset Varies Varies Varies Varies Varies Varies Varies Varies C2 Address: 0xFE; SFR Address = 0xFE; SFR Page = 0x0F Bit Name Function 7:0 REVID[7:0] Revision ID. This read-only register returns the 8-bit revision ID. For example: 0x00 = Revision A. 307 Rev. 1.2

C8051F50x/F51x C2 Register Definition 28.4. FPCTL: C2 Flash Programming Control Bit 7 6 5 4 3 2 1 0 Name FPCTL[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 C2 Address: 0x02 Bit Name Function 7:0 FPCTL[7:0] Flash Programming Control Register. This register is used to enable Flash programming via the C2 interface. To enable C2 Flash programming, the following codes must be written in order: 0x02, 0x01. Note that once C2 Flash programming is enabled, a system reset must be issued to resume normal operation. C2 Register Definition 28.5. FPDAT: C2 Flash Programming Data Bit 7 6 5 4 3 2 1 0 Name FPDAT[7:0] Type R/W Reset 0 0 0 0 0 0 0 0 C2 Address: 0xB4 Bit Name Function 7:0 FPDAT[7:0] C2 Flash Programming Data Register. This register is used to pass Flash commands, addresses, and data during C2 Flash accesses. Valid commands are listed below. Code Command 0x06 Flash Block Read 0x07 Flash Block Write 0x08 Flash Page Erase 0x03 Device Erase Rev. 1.2 308

C8051F50x/F51x 28.2. C2 Pin Sharing The C2 protocol allows the C2 pins to be shared with user functions so that in-system debugging and Flash programming may be performed. This is possible because C2 communication is typically performed when the device is in the halt state, where all on-chip peripherals and user software are stalled. In this halted state, the C2 interface can safely ‘borrow’ the C2CK (RST) and C2D pins. In most applications, external resistors are required to isolate C2 interface traffic from the user application. A typical isolation configuration is shown in Figure 28.1. C8051Fxxx RST (a) C2CK Input (b) C2D Output (c) C2 Interface Master Figure 28.1. Typical C2 Pin Sharing The configuration in Figure 28.1 assumes the following: 1. The user input (b) cannot change state while the target device is halted. 2. The RST pin on the target device is used as an input only. Additional resistors may be necessary depending on the specific application. 309 Rev. 1.2

C8051F50x/F51x DOCUMENT CHANGE LIST Revision 0.2 to Revision 1.0  Added documentation for 40-pin QFN devices in all relevant chapters.  Change oscillator specification for devices initially specified to have ±1.0% oscillators. All devices are now rated for ±0.5% across operating voltage and temperature.  Removed all content from “1. System Overview”after block diagrams.  Updated “5. Electrical Characteristics”—Updated various specifications and filled in all TBD values for all specifications.  Updated “Table 5.11. Voltage Reference Electrical Characteristics”—Changed Minimum external reference input voltage from 0 V to 1 V.  Updated “9. Comparators”—Fixed incorrect references to SFR Definitions 7.x.  Updated “Table 13.1”—Added SFRs SN0, SN1, SN2, and SN3 to SFR map.  Updated “SFR Definition 19.2” (OSCICN) - Removed errant row for Bit 6. Also, Bit 3 defintion changed to a Reserved bit from an Unused bit.  Updated “20. Port Input/Output”—Added Port 4 to the crossbar diagrams and documentation.  Updated “27.4. Watchdog Timer Mode”—Fixed incorrect references from Module 2 as the watchdog module to Module 5. Revision 1.0 to Revision 1.1  Updated “Ordering Information” on page 20 and Table 2.1, “Product Selection Guide,” on page 21 to include -A (Automotive) devices and automotive qualification information.  Updated supply current related specifications throughout “5. Electrical Characteristics”.  Updated SFR Definition 8.1 to change VREF high setting to 2.20 V from 2.25 V.  Updated Table 5.12 on page 51 and Figure 9.1 on page 75 to indicate that Comparators are powered from V and not V . IO DDA  Updated Table 5.12 on page 51 to fix Comparator Supply Current Typical values for Modes 2 and 3.  Updated the Gain Table in “6.3.1. Calculating the Gain Value” to fix the ADC0GNH Value in the last row.  Updated Table 11.1 on page 89 with correct timing for all branch instructions, MOVC, and CPL A.  Updated “15.1. Programming the Flash Memory” to clarify behavior of 8-bit MOVX instructions and when writing/erasing Flash.  Updated SFR Definition 15.3 to include FLEWT bit definition. This bit must be set before writing or erasing Flash. Also updated Table 5.5 to reflect new Flash Write and Erase timing.  Updated “17.7. Flash Error Reset” with an additional cause of a Flash Error reset.  Updated “20.1.3. Interfacing Port I/O in a Multi-Voltage System” to remove note regarding interfacing to voltages above VIO.  Updated “23. SMBus”to remove all hardware ACK features, including SMB0ADM and SMB0ADR SFRs.  Updated “24.3.2. Data Reception” to clarify UART receive FIFO behavior.  Updated SFR Definition 24.1 for SCON0 to correct SFR Page to 0x00 from All Pages. Note: All items from the C8051F50x-F51x Errata dated July 1, 2009 are incorporated into this data sheet. Rev. 1.2 310

C8051F50x/F51x Revision 1.1 to Revision 1.2  Updated “1. System Overview” with a voltage range specification for the internal oscillator.  Updated Table 5.6 on page 47 with new conditions for the internal oscillator accuracy. The internal oscillator accuracy is dependent on the operating voltage range.  Updated “5. Electrical Characteristics” to remove the internal oscillator curve across temperature diagram.  Updated SFR Definition 10.1 (REG0CN) with a new definition for Bit 6. The bit 6 reset value is 1b and must be written to 1b.  Updated “21. Local Interconnect Network (LIN)” with a voltage range specification for the internal oscillator.  Updated “22. Controller Area Network (CAN0)” with a voltage range specification for the internal oscillator.  Updated SFR Definition 8.1 (REF0CN) with oscillator suspend requirement for ZTCEN.  Updated "16.3 Suspend Mode" with note regarding ZTCEN.  Updated Figure 6.4 with new timing diagram when using CNVSTR pin.  Added Port 2 Event and Port 3 Events to wake-up sources in Section 19.2.1.  Updated LIN Register Definitions 21.9 and 21.10 with correct reset values.  Updated C2 Register Definitions 28.2 and 28.3 with correct C2 and SFR addresses. 311 Rev. 1.2

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