#include <TwoWire.h> 
 
void setup() 
{ 
  Wire.begin();        // join i2c bus (address optional for master) 
  Serial.begin(9600);  // start serial for output 
} 
 
void loop() 
{ 
  Wire.requestFrom(2, 6);    // request 6 bytes from slave device #2 
 
  while(Wire.available())    // slave may send less than requested 
  { 
    char c = Wire.receive(); // receive a byte as character 
    Serial.print(c);         // print the character 
  } 
 
  delay(500); 
} 

#include <TwoWire.h> 
 
void setup() 
{ 
  Wire.begin(4);                // join i2c bus with address #4 
  Wire.onReceive(receiveEvent); // register event 
  Serial.begin(9600);           // start serial for output 
} 
 
void loop() 
{ 
  delay(100); 
} 
 
// function that executes whenever data is received from master 
// this function is registered as an event, see setup() 
void receiveEvent(int howMany) 
{ 
  while(1 < Wire.available()) // loop through all but the last 
  { 
    char c = Wire.receive(); // receive byte as a character 
    Serial.print(c);         // print the character 
  } 
  int x = Wire.receive();    // receive byte as an integer 
  Serial.println(x);         // print the integer 
}