Arduino/hardware/libraries/Wire/examples/digital_potentiometer/digital_potentiometer.pde

// I2C Digital Potentiometer
// by Nicholas Zambetti <http://www.zambetti.com>
// and Shawn Bonkowski <http://people.interaction-ivrea.it/s.bonkowski/>

// Demonstrates use of the Wire library
// Controls AD5171 digital potentiometer via I2C/TWI

// Created 31 March 2006

#include <Wire.h>

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

byte val = 0;

void loop()
{
  Wire.beginTransmission(44); // transmit to device #44 (0x2c)
                              // device address is specified in datasheet
  Wire.send(0x00);            // sends instruction byte  
  Wire.send(val);             // sends potentiometer value byte  
  Wire.endTransmission();     // stop transmitting

  val++;        // increment value
  if(val == 64) // if reached 64th position (max)
  {
    val = 0;    // start over from lowest value
  }
  delay(500);
}