55 lines
2.0 KiB
Arduino
55 lines
2.0 KiB
Arduino
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/* this works with volt meter (MCP23S17 on 3.3v does not output enough power for LEDs)
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LED lights w/o resistor, not light with 56 ohm resistor
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blink LED on MCP23S17 port A pin
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from Example 41.1 - Microchip MCP23017 with Arduino
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http://tronixstuff.com/tutorials > chapter 41
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http://tronixstuff.com/2011/08/26/tutorial-maximising-your-arduinos-io-ports/
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John Boxall | CC by-sa-nc
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from http://69.5.26.215/forum/?id=10945&page=3 #35
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modified to test MCP23S17 (SPI) using syntax from
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http://arduino.stackexchange.com/questions/16348/how-do-you-use-spi-on-an-arduino
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>
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SPISettings from http://arduino.stackexchange.com/questions/14191/mcp23s17-programming-iodirx-register-works-in-loop-but-not-in-setup
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*/
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#include <SPI.h>
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const uint8_t ADDR = 0x20; //MCP23S17 address, all ADDR pins are grounded
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const uint8_t OPCODE_WRITE = (ADDR << 1); //MCP23S17 opcode write has LSB clear
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const uint8_t IODIRA = 0x00; //LEDs are on port A
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const uint8_t GPIOA = 0x12;
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uint8_t LED_state = 0; //bit wise
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void IOEWrite(const uint8_t registerAddr, const uint8_t data)
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{
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SPI.beginTransaction(SPISettings (SPI_CLOCK_DIV8, MSBFIRST, SPI_MODE0)); //slower clock
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digitalWrite(SS, LOW); //enable Slave Select
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SPI.transfer(OPCODE_WRITE); //write command
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SPI.transfer(registerAddr); //register address to write data to
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SPI.transfer(data); //data
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digitalWrite(SS, HIGH); //disable Slave Select
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SPI.endTransaction(); //release the SPI bus
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}
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void setup()
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{
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Serial.begin(9600);
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pinMode(SS, OUTPUT); //configure controller's Slave Select pin to output
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digitalWrite(SS, HIGH); //disable Slave Select
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SPI.begin();
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IOEWrite(IODIRA, 0x00); //configure IODIRA register to output
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}
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void loop()
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{
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IOEWrite(GPIOA, LED_state); //set all GPIOA pins
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delay(2000);
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//Serial.println(LED_state, BIN); //prints alternating 0 and 11111111
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LED_state = ~LED_state; //toggle LED on/off
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}
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