Switching power with the Arduino over a I2C connected PCF8574

1 Goal

This little project wants do demonstrate how it is possible to switch a great number of lines with one single Arduino controller. It uses the PCF8574P chip. It is actually a reimplementation of this project:

• http://circuitsforbeginners.blogspot.com/2009/11/project-rolling-dice-expanding-arduino.html

2 References

• http://www.arduino.cc/en/Reference/Wire The WIRING "Wire" library
• http://www.neufeld.newton.ks.us/electronics/?p=241 A project in which the workings of the I2C protocol are well described
• www.nxp.com/documents/data_sheet/PCF8574.pdf The Datasheet for the PCF8574

3 The Scheme

4 The Code

#define CARD_ADR (0x4 << 3 | 0x0) // address 0100000

#include <Wire.h>

void setup()
{
  Wire.begin(); // join i2c bus (address optional for master)
}

void loop()
{
  /* switch on P0 */
  Wire.beginTransmission(CARD_ADR);
  Wire.send(B00000001);
  Wire.endTransmission();
  delay(1000);
 
  /* switch off all pins */
  Wire.beginTransmission(CARD_ADR);
  Wire.send(B00000000);
  Wire.endTransmission();
  delay(1000);   

  /* switch on P1 */
  Wire.beginTransmission(CARD_ADR);
  Wire.send(B00000010);
  Wire.endTransmission();
  delay(1000);
 
  /* switch off all pins */
  Wire.beginTransmission(CARD_ADR);
  Wire.send(B00000000);
  Wire.endTransmission();
  delay(1000);   
 
}

5 The Movie

You can watch the movie which explains this subproject on my Youtube channel.