Arduino I2C setup

I2C_Master_Reader.pde

// Running on an Arduino Mega2560 R.3
// #20 - SDA
// #21 - SCL

#include <Wire.h>

void setup() {
  pinMode(13, OUTPUT);
  Wire.begin();
  Serial.begin(9600);
}

void loop() {
  Wire.requestFrom(2, 6); // request 6 bytes from slave #2

  while(Wire.available()) {
    char c = Wire.receive();
    Serial.print(c);
    
    // blink #13 to show communication
    digitalWrite(13, HIGH);
    delay(100);
    digitalWrite(13, LOW);
  }
  delay(500);
}

I2C_Slave_Writer.pde

// Running on an Arduino Diecimila
// #4 - SDA
// #5 - SCL

#include <Wire.h>

void setup() {
  pinMode(13, OUTPUT);
  Wire.begin(2);
  Wire.onRequest(requestEvent);
}

void loop() {
  delay(100);
}

void requestEvent() {
  Wire.send("hello ");
  
  // blink #13 to show communication
  digitalWrite(13, HIGH);
  delay(100);
  digitalWrite(13, LOW);
}