cchhiippKKIITT™™ BBaassiicc II//OO SShhiieelldd BBooaarrdd RReeffeerreennccee MMaannuuaall Revision: July 16, 2011 1300 NE Henley Court, Suite 3 Pullman, WA 99163 (509) 334 6306 Voice | (509) 334 6300 Fax Overview The chipKIT Basic I/O Shield is a input/output expansion board designed for use with chipKIT microcontroller boards such as the Uno32™ and the Max32™. The Basic I/O Shield is designed to provide a range of input/output devices suitable for beginners learning about microcontrollers and various types of I/O devices, or for use by more advanced user to provide inputs or outputs for their own projects. The Basic I/O Shield provides simple digital input devices such as switches and buttons, and digital output devices such as discrete LEDs and high current open FET drivers. It provides more advanced devices such as an I2C EEPROM, an I2C temperature sensor, and organic LED graphic display. A potentiometer is also provided for use as an analog input device. The Basic I/O Shield is designed to the same form factor as the Uno32 board, but is also useable with the Max32 board. Features: 128x32 pixel OLED graphic display I2C temperature sensor 256Kbit I2C EEPROM I2C daisy chain connector 4 push buttons 4 slide switches 8 discrete LEDs 4 open drain FET drivers Analog potentiometer Doc: 502-216 page 1 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual chipKIT Basic I/O Shield Hardware Overview The Basic I/O Shield has the following hardware features: 1) Push Buttons Four push buttons provide momentary contact discrete digital inputs. These can be accessed using the digitalRead function. 2) Slide switches Four slide switches that provide discrete digital inputs. These can be accessed using the digitalRead function. 3) J2 – Shield Power Connector This connector powers the board, receiving power from the chipKIT microcontroller board. www.digilentinc.com page 2 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual 4) J3 – Analog Signal Connector Pin 1 (analog signal A0) is connected to a potentiometer. Pins 5 and 6 (labeled as A4 and A5) provide access to the I2C signals SDA and SCL for the I2C bus. The I2C bus is used to access the temperature sensor and the EEPROM and for the I2C daisy chain connector. Note: On the Uno32 it is necessary to set jumpers JP6 & JP7 to the correct position for accessing the I2C signals on that board. On the Max32 board, it is necessary to use jumper wires to bring the I2C signals onto the board, as the connector providing the I2C bus on the Max32 board doesn’t contact the Basic I/O Shield. 5) Discrete LEDs Eight LEDs that provide discrete digital outputs. These can be accessed individually using the digitalWrite function. The LEDs are connected to the low eight bits of microcontroller PORTE and all eight can be written at the same time by writing to PORTE. 6) IC2 – Temperature Sensor This is a Microchip TCN75A digital temperature sensor. It is accessed via the I2C bus. 7) JP2/JP3 – I2C Pull-up Resistor Enable Jumpers These jumpers are used to enable or disable the presence of the I2C pull-up resistors on the I2C bus. Having the shorting blocks installed enables the resistors. Removing the shorting blocks disables them. 8) J11 – I2C Daisy Chain Connector This is a 2x4 pin header connector that provides access to the I2C signals SDA and SCL as well as power from the 3.3V power bus and ground. This can be used to extend the I2C bus off of the board and to power external I2C device. Digilent has cables and a selection of I2C peripheral modules that can be accessed using this connector. 9) Potentiometer This is a 10K ohm potentiometer connected across VCC3V3 and ground. It provides an analog input voltage to analog input A0. 10) J1 and J2 – Digital Signal Connectors These connectors bring digital signals from the chipKIT microcontroller board onto the Basic I/O Shield board. 11) Organic LED Graphic Display This is a 128x32 pixel monochrome OLED graphic display panel. This display panel is accessed using the SPI interface. 12) J9 & J10 – Digital I/O Signal Connectors These are screw terminal connectors that provide access to digital I/O signals 3, 5, 6, and 9. These are four of the PWM signals from the chipKIT microcontroller board. 13) J6 – Open Drain FET Power Connector This provides access to the power connections for the open drain FETs. 14) , J7, & J8 – Open Drain FET Output These provide access to the outputs of the open drain FETs. www.digilentinc.com page 3 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual chipKIT Basic I/O Shield Hardware Description Introduction Power off sequence: Send Display Off command The following gives a basic description of the Power off VBAT input/output hardware contained in the Basic Delay 100ms I/O Shield and how to use it. Refer to Appendix Power off VDD A for a table showing pin definitions, and Appendix B for example code to use the OLED The display has a D/C pin (display or graphic display. command select) that is used to determine whether bytes sent to the display are OLED Graphic Display interpreted as commands or as display data. The D/C pin is set HIGH for display buffer The Basic I/O board provides a 128x32 pixel, access and LOW for command access. Organic LED (OLED), graphic display panel. The graphic display panel used is the The RES pin is used to reset the SG1306 WiseChip/Univision UG-23832HSWEG04. This display controller. The RES pin is driven LOW display uses the Soloman Systech SSD1306 for reset and driven HIGH for normal operation. display controller. The low going reset pulse must be a minimum of 3us (microseconds) for the display controller The UG2832 has a power on/power off to reset correctly. sequence that should be followed. Failure to follow the power on/power off sequence can The UG2832 is a serial device that is accessed shorten the life of the display. The Basic I/O using SPI. It is however, a write-only device. It provides two FETs for software control of the is not possible to read back either the display two power supplies for the display. The buffer contents or any kind of status from the VDD_EN control is used to turn on/off the panel. The maximum SPI clock frequency power to the logic of the display. The supported by the UG2832 is 10Mhz. Due to pin VBAT_EN control is used to turn on/off power limitations between the Basic I/O and the to the OLED display itself. These two pins Uno32 board, the select pin (SS) is wired low have pull-up resistors to turn off their on the Basic I/O board and the display is respective power supplies when not being always enabled to receive data over the SPI driven. The pin is made an output and driven interface. low to turn on the power supply. Digilent has a library for use with the Basic I/O Power on sequence: that provides functions for initializing the Apply power to VDD display and rendering simple text and graphics Send Display Off command onto the display. This library can be used as-is Initialize display to desired operating mode or as a starting point for a more sophisticated Clear screen graphics library. This library is available on the Apply power to VBAT Digilent web site and in the third part libraries Delay 100ms repository on github. Send Display On command Appendix B provides example code that shows initializing the display and writing to it. www.digilentinc.com page 4 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual Discrete Digital I/O Devices closure to ground. These can be used to switch external loads, such as relay coils, The Basic I/O Shield provides various discrete solenoids, stepper motors, and so on. digital I/O devices. These can be accessed using the digitalRead and digitalWrite The FETs used are the NTHD4508N. These FETs are rated for a maximum V (voltage functions. The pinMode function is used to set DS from drain to source) of 20V. They are rated for the pin to input or output. a maximum continuous current of 3.0A at 25ºC and 2.2A at 85ºC. For more detailed When the buttons and switches on the Basic specifications for the FETs refer to the data I/O are not being used, the pins are available sheet available from the On Semiconductor on the pass-through shield connectors for use web site. by other shields in the stack. The pins used by the LEDs are also available, however the The FETs are labeled Q1A (pin 9), Q1B (pin presence of the LEDs on the lines will load 6), Q2A (pin 5), and Q2B (pin 3). These four them down, possibly causing some devices to pins are also four of the PWM outputs not work. It is safe to use any of these pins as supported by the chipKIT boards and the FETs either inputs or outputs. can be switched using pulse width modulation (PWM) using the analogWrite function. Push Buttons: There are four push buttons switches labeled BTN1 (pin 4), BTN2 (pin 34), An FET is switched on by driving its gate high. BTN3 (pin 36), and BTN4 (pin 37). The When the FET is on, it provides a low digitalRead function will return LOW if the impedance path to ground (similar to a closed button is not pressed and HIGH when the switch to ground). When the FET is switched button is pressed. off by driving its gate low, it becomes a high impedance path to ground (similar to an open Slide Switches: There are four slide switches switch to ground). Pull-down resistors are labeled SW1 (pin 2), SW2 (pin 7), SW3 (pin 8) connected to the gate of each FET to ensure and SW4 (pin 35). The digitalRead function will that it is off unless being actively driven high by return LOW when the switch is down (toward the microcontroller on the chipKIT board. the push buttons) and HIGH when the switch is up (toward the OLED display). The FET outputs are accessed via the screw terminal connectors J7 and J8 on the left side LEDs: There are eight LEDs, labeled LD1 – of the board. The digital signals used to switch LD8 accessed as digital pins 33 – 26. An LED the FETs on and off are also available on will be illuminated when the corresponding pin screw terminal connectors J9 and J10 at the is set to the HIGH state using the digitalWrite left side of the upper edge of the board. function and off when set to the LOW state. A FET is used to switch an external load, such as a relay coil, on and off. The load is wired The LEDs are attached to the low eight bits of between the positive side of an external power PORTE, with LD1 connected to PORTE bit 0, supply and the output of the FET. When the and LD8 connected to PORTE bit 7. An 8-bit FET is switched on, current will flow from the value written to PORTE (or LATE) will display external power supply through the load and the the corresponding binary value on the LEDs. FET to ground. Open Drain FET Outputs FETs are often used to switch highly inductive loads, such as relay coils, solenoids, and The Basic I/O provides four open drain FET motors. When the current through an inductive outputs. These are low-side N-channel devices load is switched off, a voltage spike will occur and can be used to provide a digital switch www.digilentinc.com page 5 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual that can damage the FET. The Basic I/O pull-up resistors if a different value is needed provides clamp diodes (also called snubber or or some other device on the bus is providing flyback diodes) to clamp the voltage spike and the pull-ups. The on-board pull-up resistors are feed the current back to the external supply. enabled by install shorting blocks on JP2 and JP3. Removing the shorting blocks disables Screw terminal connector J6 is used to provide the pull-up resistors. the power and ground connections back to the external power supply. The negative (-) pin of Digilent has several small I/O modules J6 connects the external supply ground with available that can be connected using the I2C the Basic I/O ground, and the positive (+) connector. These include a 3-axis terminal connects the Basic I/O to the external accelerometer, 4-channel, 12-bit A/D supply voltage. converter, serial character LCD panel, 3-axis gyroscope, real-time clock/calendar, and I/O The unloaded two pin header JP1 can be used expander. to connect the board VCC5V0 power supply bus to the external power supply bus so that EEPROM: A 256Kbit (32Kbyte), I2C EEPROM the board 5V supply can be used instead of an is provided using a Microchip 24LC256. This external supply. In this case, J6 is used to EEPROM, IC1, is located on the bottom left of connect the board supply to the external loads. the board, just below the chipKIT logo. If this is done, the total current consumed by all external loads must not exceed 2A or the The seven bit I2C device address for the current rating of the board power supply EEPROM is ‘1010000’. (whichever is less). Digilent provides a library for accessing this I2C Bus EEPROM. The library is available on the Digilent web site and in the third party libraries The I2C bus from the chipKIT microcontroller repository on github. board is brought onto the Basic I/O Shield. There are two I2C devices on the board and a For complete technical documentation on the connector for taking the I2C bus off of the 24LC256, refer to the data sheet available on board to connect to additional external I2C the Microchip web site. devices. Temperature Sensor: A digital temperature I2C Connector: Connector J11 can be used to sensor is provided using a Microchip TCN75A extend the I2C bus off of the board to connect 2-Wire Serial Temperature Sensor. The to additional external I2C devices. J11 is a temperature sensor, IC2, is an I2C device, and standard 2x4 pin header connector with 0.100” is located in the lower right corner of the board. spaced pins. It provides access to the I2C signals, SCL and SDA, plus VCC3V3 and The TCN75A is rated for an accuracy of +/-1ºC ground. The VCC3V3 can be used to power and has selectable resolution from 0.5ºC down external I2C devices. to 0.0625ºC. The seven bit device address is ‘1001000’. The I2C bus uses open collector drivers to allow multiple devices to drive the bus signals. Digilent provides a library for accessing the This means that pull-up resistors must be temperature sensor. This library is available on provided to supply the logic high state for the the Digilent web site and in the third party signals. The Basic I/O provides 2.2Kohm pull- library repository on github. up resistors. Generally, only one set of pull-up resistors are used on the bus. Jumpers JP2 The TCN75A provides an alert output that can and JP3 can be used to disable the on-board be programmed for various functions. This www.digilentinc.com page 6 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual output can be accessed using JP4, which is adjacent to IC2. For complete technical documentation on the TCN75A, refer to the data sheet available on the Microchip web site. Potentiometer A potentiometer (pot) is provided on the board to be used as an analog signal source or analog control input. The pot is a 10Kohm trimmer pot connected between the VCC3V3 supply and ground. The wiper of the pot is connected to analog input A0. The pot is read using the analogRead function. www.digilentinc.com page 7 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual Appendix A: chipKIT Basic I/O Shield Pinout Table Uno32 Max32 Function Description Notes pin # pin # 10 10 RES OLED reset JP4 on Uno32 39 83 DC OLED data/command select 13 13 SCLK OLED serial clock 11 11 SDIN OLED serial data in JP7 on Uno32/JP4 on Max32 40 84 VBAT_EN OLED VBAT enable 38 82 VDD_EN OLED VDD enable 33 77 LD1 User LED 32 76 LD2 User LED 31 75 LD3 User LED 30 74 LD4 User LED 29 73 LD5 User LED 28 72 LD6 User LED 27 71 LD7 User LED 26 70 LD8 User LED 4 4 BTN1 Push button 34 78 BTN2 Push button 36 79 BTN3 Push button 37 80 BTN4 Push button 2 2 SW1 Slide switch 7 7 SW2 Slide switch 8 8 SW3 Slide switch 35 79 SW4 Slide switch 3 3 OC1 Open drain/PWM output 5 5 OC2 Open drain/PWM output 6 6 OC3 Open drain/PWM output 9 9 OC4 Open drain/PWM output 19 59 SCL I2C clock JP8 on Uno32/jumper wire on Max32 18 58 SDA I2c data JP6 on Uno32/jumper wire on Max32 14 54 A0 Potentiometer www.digilentinc.com page 8 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual Appendix B: Example Driver Code The following gives an example of code to initialize the display controller and write the contents of a memory buffer into the display. This example is written for the chipKIT Uno32 board. Symbol and Variable Declarations /* ------------------------------------------------------------ */ /* Pin definitions for access to OLED control signals on chipKIT Uno32 */ #define prtVddCtrl IOPORT_F #define prtVbatCtrl IOPORT_F #define prtDataCmd IOPORT_F #define prtReset IOPORT_G #define bitVddCtrl BIT_6 #define bitVbatCtrl BIT_5 #define bitDataCmd BIT_4 #define bitReset BIT_9 /* ------------------------------------------------------------ */ /* Symbols describing the geometry of the display. #define cbOledDispMax 512 //max number of bytes in display buffer #define ccolOledMax 128 //number of display columns #define crowOledMax 32 //number of display rows #define cpagOledMax 4 //number of display memory pages /* ------------------------------------------------------------ */ /* This array is the off-screen frame buffer used for rendering. ** It isn't possible to read back from the OLED display device, ** so display data is rendered into this off-screen buffer and then ** copied to the display. */ BYTE rgbOledBmp[cbOledDispMax]; www.digilentinc.com page 9 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual PIC32 Hardware Initialization The following function initializes the PIC32 hardware for talking to the display. It initializes the SPI controller and sets the control pins to be outputs. /* ------------------------------------------------------------ */ /*** OledHostInit ** ** Parameters: ** none ** ** Return Value: ** none ** ** Errors: ** none ** ** Description: ** Perform PIC32 device initialization to prepare for use ** of the OLED display. ** This example is hard coded for the chipKIT Uno32 and ** SPI2. */ void OledHostInit() { unsigned int tcfg; /* Initialize SPI port 2. */ SPI2CON = 0; SPI2BRG = 15; //8Mhz, with 80Mhz PB clock SPI2STATbits.SPIROV = 0; SPI2CONbits.CKP = 1; SPI2CONbits.MSTEN = 1; SPI2CONbits.ON = 1; /* Make pins RF4, RF5, and RF6 be outputs. */ PORTSetBits(IOPORT_F, bitVddCtrl|bitVbatCtrl|bitDataCmd); PORTSetPinsDigitalOut(prtDataCmd, bitDataCmd); //Data/Command# select PORTSetPinsDigitalOut(prtVddCtrl, bitVddCtrl); //VDD power control (1=off) PORTSetPinsDigitalOut(prtVbatCtrl, bitVbatCtrl); //VBAT power control (1=off) /* Make the RG9 pin be an output. On the Basic I/O Shield, this pin ** is tied to reset. */ PORTSetBits(prtReset, bitReset); PORTSetPinsDigitalOut(prtReset, bitReset); } www.digilentinc.com page 10 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual Display Controller Initialization The following function performs initialization of the display controller on the display panel. This performs the power up sequence on the display and initializes it for a non-interleaved display buffer with the origin in the upper left corner. /* ------------------------------------------------------------ */ /*** OledDspInit ** ** Parameters: ** none ** ** Return Value: ** none ** ** Errors: ** none ** ** Description: ** Initialize the OLED display controller and turn the display on. */ void OledDspInit() { /* We're going to be sending commands, so clear the Data/Cmd bit */ PORTClearBits(prtDataCmd, bitDataCmd); /* Start by turning VDD on and wait a while for the power to come up. */ PORTClearBits(prtVddCtrl, bitVddCtrl); DelayMs(1); /* Display off command */ Spi2PutByte(0xAE); /* Bring Reset low and then high */ PORTClearBits(prtReset, bitReset); DelayMs(1); PORTSetBits(prtReset, bitReset); /* Send the Set Charge Pump and Set Pre-Charge Period commands */ Spi2PutByte(0x8D); Spi2PutByte(0x14); Spi2PutByte(0xD9); Spi2PutByte(0xF1); /* Turn on VCC and wait 100ms */ PORTClearBits(prtVbatCtrl, bitVbatCtrl); DelayMs(100); /* Send the commands to invert the display. This puts the display origin ** in the upper left corner. */ www.digilentinc.com page 11 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual Spi2PutByte(0xA1); //remap columns Spi2PutByte(0xC8); //remap the rows /* Send the commands to select sequential COM configuration. This makes the ** display memory non-interleaved. */ Spi2PutByte(0xDA); //set COM configuration command Spi2PutByte(0x20); //sequential COM, left/right remap enabled /* Send Display On command */ Spi2PutByte(0xAF); } www.digilentinc.com page 12 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual Display Memory Update This function copies the contents of a 512 byte buffer from PIC32 memory to the display. The display memory is organized as four pages of 128 bytes each. Each memory page corresponds to an eight pixel high stripe across the display. Each byte in the memory page corresponds to an eight pixel high column on the display. The least significant bit in a display byte is the top most pixel, and the most significant bit the bottom most pixel. The first byte in the page corresponds to the left most pixels on the display and the last byte the right most pixels. This function assumes that the display buffer to be copied is the global variable rgbOledBmp /* ------------------------------------------------------------ */ /*** OledUpdate ** ** Parameters: ** none ** ** Return Value: ** none ** ** Errors: ** none ** ** Description: ** Update the OLED display with the contents of the memory buffer */ void OledUpdate() { int ipag; int icol; BYTE * pb; pb = rgbOledBmp; for (ipag = 0; ipag < cpagOledMax; ipag++) { PORTClearBits(prtDataCmd, bitDataCmd); /* Set the page address */ Spi2PutByte(0x22); //Set page command Spi2PutByte(ipag); //page number /* Start at the left column */ Spi2PutByte(0x00); //set low nybble of column Spi2PutByte(0x10); //set high nybble of column PORTSetBits(prtDataCmd, bitDataCmd); /* Copy this memory page of display data. */ OledPutBuffer(ccolOledMax, pb); pb += ccolOledMax; } } www.digilentinc.com page 13 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual Low Level SPI Functions The following functions are used to write data to the display panel using the SPI controller. /* ------------------------------------------------------------ */ /*** OledPutBuffer ** ** Parameters: ** cb - number of bytes to send/receive ** rgbTx - pointer to the buffer to send ** ** Return Value: ** none ** ** Errors: ** none ** ** Description: ** Send the bytes specified in rgbTx to the slave. */ void OledPutBuffer(int cb, BYTE * rgbTx) { int ib; BYTE bTmp; /* Write/Read the data */ for (ib = 0; ib < cb; ib++) { /* Wait for transmitter to be ready */ while (SPI2STATbits.SPITBE == 0); /* Write the next transmit byte. */ SPI2BUF = *rgbTx++; /* Wait for receive byte. */ while (SPI2STATbits.SPIRBF == 0); bTmp = SPI2BUF; } } /* ------------------------------------------------------------ */ /*** Spi2PutByte ** ** Parameters: ** bVal - byte value to write ** ** Return Value: ** Returns byte read ** ** Errors: ** none ** ** Description: ** Write/Read a byte on SPI port 2 www.digilentinc.com page 14 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

chipKIT Basic I/O Shield Reference Manual */ BYTE Spi2PutByte(BYTE bVal) { BYTE bRx; /* Wait for transmitter to be ready */ while (SPI2STATbits.SPITBE == 0); /* Write the next transmit byte. */ SPI2BUF = bVal; /* Wait for receive byte. */ while (SPI2STATbits.SPIRBF == 0); /* Put the received byte in the buffer. */ bRx = SPI2BUF; return bRx; } www.digilentinc.com page 15 of 15 Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.