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keybrd/unit_tests/MCP23S17_write/MCP23S17_write.ino
2016-08-31 20:29:59 -06:00

55 lines
2.0 KiB
C++

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