使用Mega2560的I2C通訊協定與MCP23018 IO extander chip溝通控制RGB LED－魚的方舟圖形語言的世界 - LabVIEW & Arduino & Python工作室 - 新網站https://labview-tech.blogspot.com/

這一個範例是說明如何使用Mega2560與MCP23018作I2C通訊，

MCP23018為一個16通道的IO擴充IC，可以一口氣增加16個Digtal input 與 output，

在使用Arduino的通訊協定時，我們會用到Wire的函式庫，所以一開始要將Wire.h include進來，

我參考了一些網站來撰寫這個範例:

1. https://github.com/maniacbug/Arduino/blob/master/Double_Seven_LED_Test/Double_Seven_LED_Test.pde

2. http://byterule.com/2013/8/21/i2c-arduino-to-mcp-23018.aspx

3. http://www.arduino.cc/en/reference/wire

基本的接腳為:

MCP23018/Arduino

Addr -> gnd (gets mcpaddr for wire of 0x20)

Reset-> V+

VSS -> gnd

Vdd -> v+

SDA-> 20 W/pullup resistor 1.5K+

SCL -> 21 W/pullup resistor 1.5K+

GPB0--> LED G

GPB1--> LED B

GPB2--> LED R

Arduino code為:

#include <Wire.h>

const uint8_t I2C_MCP23018 = B0100000;

// MCP23018 registers

const uint8_t IODIRA = 0x0;
const uint8_t IODIRB = 0x1;
const uint8_t IOCON = 0xA;
const uint8_t IOCON_SEQOP[] = { IOCON, 5 };
const uint8_t GPPUA = 0x0C;
const uint8_t GPPUB = 0x0D;
const uint8_t GPIOA = 0x12;
const uint8_t GPIOB = 0x13;
const uint8_t OLATA = 0x14;
const uint8_t OLATB = 0x15;

void setup()
{
Serial.begin(9600); //start serial for debug purpose

delay(2000); //wait for the pc to be able to connect to serial this is due to some issues with serial communications and my pc I think due to the number of devices connected oh well

Wire.begin();

// Set all pins to outputs
Wire.beginTransmission(I2C_MCP23018);
Wire.write(IODIRA);
Wire.write(0x00);
Wire.write(0x00);
Wire.endTransmission();
}

void loop()
{
Wire.beginTransmission(I2C_MCP23018);
Wire.write(GPIOA);
Wire.write(0xff);
Wire.write(B00000001); //set PGPB0 1/high
Wire.endTransmission();
delay(1000);
Wire.beginTransmission(I2C_MCP23018);
Wire.write(GPIOA);
Wire.write(0xff);
Wire.write(B00000010); //set PGPB1 1/high
Wire.endTransmission();
delay(1000);
Wire.beginTransmission(I2C_MCP23018);
Wire.write(GPIOA);
Wire.write(0xff);
Wire.write(B00000100); //set PGPB2 1/high
Wire.endTransmission();
delay(1000);
}