/*
 Arduino MCP23016 IO Expander Programming
 https://www.bristolwatch.com/arduino/arduino_mcp23016.htm
 by Lewis Loflin lewis@bvu.net
*/


/*

  The address for the MCP23016 is 0x20.
  There are eight resistor/LED indicators on pins 21 - 28.
  This demo produces a binary count of 0 to 255
  on Port0 on the MCP23016.

*/

#include <Wire.h> // specify use of Wire.h library.
int i = 0;

void setup()   {
  Wire.begin();
  Wire.beginTransmission(0x20);  // setup out direction registers
  Wire.write(0x06);  // pointer
  Wire.write(0x00);  // DDR Port0 all output
  Wire.write(0xFF);  // DDR Port1 all input
  Wire.endTransmission();
}

void loop() {

  i++;
  Wire.beginTransmission(0x20);  
  // set mcp23016 for all output
  Wire.write(0x00); // begin here
  Wire.write(i);
  Wire.endTransmission();
  if (i > 255) i = 0;
  delay(1000); // }

} // end loop