#include <Wire.h>

void setup()
{
  Wire.begin(); // join i2c bus (address optional for master)
  pinMode (12, INPUT);
}

byte x = 0;

void loop()
{
  int sensorvalue = digitalRead (12);
  
   if (sensorvalue == 1)                                    
  {
  Wire.beginTransmission(4); // transmit to device #4
  x=1;
  Wire.write(x);              // sends one byte  
  Wire.endTransmission();    // stop transmitting

  }

  else{
      Wire.beginTransmission(4); // transmit to device #4
  x=0;
  Wire.write(x);              // sends one byte  
  Wire.endTransmission();    // stop transmitting
  }

  
}