PCF8574T test

// test for PCF8574T board, used for LCD interface
// runs each line high in sequence, then all on and off a couple times
// I use the same basic routine to figure out shift register outputs
// feel free to take the guts from this for your code.


#include <Wire.h>

byte i2caddr=0x27;

void setup() {

  Wire.begin();
}

void loop() {

// run one bit high, from 0b00000001 to 0b10000000
// for mine, 0b00001000 is the backlight control
// bits 0b00010000 to 0b10000000 are the data bus bits 4 to 7.
for (byte b=0;b<8;b++){
 bwrite(1<<b);
  delay (500);
}

// flash all pins on and off 3 times
for (byte b=0;b<3;b++){
  bwrite(0xff);
  delay (300);
  bwrite(0x00);
  delay (300);
}
delay(500);
}

void bwrite(byte data){

  Wire.beginTransmission (i2caddr);
  Wire.write (data);
  Wire.endTransmission ();
}