I2C example from arduino with modifications for LightBlue(TM) testing

i2ctest.c

#include <Wire.h>

byte val = 0;
void setup() {
  Wire.begin(8);                // join i2c bus with address #8
  Wire.onRequest(requestEvent); // register event
}

void loop() {
  delay(1000);
  val ^= 1 << 0;
  
}

// function that executes whenever data is requested by master
// this function is registered as an event, see setup()
void requestEvent() {
  Wire.write(val); // respond with message of 1 bytes
  // as expected by master
}