Arduino中使用I2C通信可直接调用Wire.h库, 这个库允许Arduino链接其他I2C设备, 链接线有两条, 分别是SDA(数据行)和SCI(时钟线). 各型号Arduino的I2C对应引脚:

Arduino Board：I2C / TWI pins

Arduino Uno/Ethernet：A4 (SDA), A5 (SCL)

Arduino Mega2560：20 (SDA), 21 (SCL)

Arduino Leonardo：2 (SDA), 3 (SCL)

Arduino Due：20 (SDA), 21 (SCL), SDA1, SCL1

一般购买到的是分开的两个组件, 需要按下图这样将PCF8574T焊接到1602LCD上

PCF8574T模块4pin(Gnd, Vcc, SDA i2c数据, SCL i2c时钟)和Arduino接口的对应关系: Gnd -> Gnd, Vcc -> Vcc, SDA -> A4, SDL -> A5

获取I2C地址

#include

voidsetup() {

Serial.begin (115200); //Leonardo: wait for serial port to connect

while (!Serial) { }

Serial.println ();

Serial.println ("I2C scanner. Scanning ...");byte count = 0;

Wire.begin();for (byte i = 8; i < 120; i++) {

Wire.beginTransmission (i);if (Wire.endTransmission () == 0) {

Serial.print ("Found address:");

Serial.print (i, DEC); Serial.print ("(0x");

Serial.print (i, HEX); Serial.println (")");

count++; delay (1); //maybe unneeded?

} //end of good response

} //end of for loop

Serial.println ("Done.");

Serial.print ("Found");

Serial.print (count, DEC);

Serial.println ("device(s).");

}//end of setup

void loop() {}

运行时, 打开Serial Monitor, 将波特率设为115200, 看到的输出就是I2C地址

自带LiquidCrystal_I2C显示测试

在运行显示测试前检查是否已经安装了library: LiquidCrystal, LiquidCrystal_I2C

#include #include

//I2C地址, 一般为0x3F, 0x20或0x27

LiquidCrystal_I2C lcd(0x27,16,2);voidsetup() {

lcd.init();

lcd.backlight();//打开背光

}voidloop() {

lcd.setCursor(0,0);

lcd.print("LCD1602 iic Test");

lcd.setCursor(0,1);

lcd.print("0123456789ABCDEF");

delay(1000);

}

如果屏幕亮但是无显示, 可以调节背后的电位器让字符显示到合适的对比度.

第三方New LiquidCrystal显示测试

#include #include#includeLiquidCrystal_I2C lcd(0x27,2,1,0,4,5,6,7); //0x27 is the I2C bus address for an unmodified backpack

void setup() { //activate LCD module

lcd.begin (16,2); //for 16 x 2 LCD module

lcd.setBacklightPin(3,POSITIVE);

lcd.setBacklight(HIGH);

}voidloop() {

lcd.home ();//set cursor to 0,0

lcd.print("HELLO WORLD....");

lcd.setCursor (0,1); //go to start of 2nd line

lcd.print(millis());

delay(1000);

lcd.setBacklight(LOW);//Backlight off

delay(1000);

lcd.setBacklight(HIGH);//Backlight on

}

供电和耗电测试

硬件是Arduino NANO + 扩展板 + PCF8574T + 1602LCD, 使用输入电压12V. 扩展板本身不带IC, 只有一个电源LED, 功耗可以忽略. 在使用自带的LiquidCrystal_I2C库跑上面的测试代码时, 测得的功耗仅为0.95W左右.