// Include Arduino Wire library for I2C
#include <Wire.h>
 
// Define Slave I2C Address
#define SLAVE_ADDR 9
 
// Define LED Pin
int LED = 13;
 
// Variable for received data
int rd;
 
// Variable for ldr status
int ldrStatus;
 
void setup() {
 
  pinMode(LED, OUTPUT);
  
  // Initialize I2C communications as Slave
  Wire.begin(SLAVE_ADDR);
   
  // Function to run when data received from master
  Wire.onReceive(receiveEvent);
  
  // Setup Serial Monitor 
  Serial.begin(9600);
}
 
 
void receiveEvent() {
  // read one character from the I2C
  rd = Wire.read();
    
}
void loop() {
   delay(50);
 
  // Calculate ldr value
  ldrStatus = map(rd, 1, 255, 0, 1023);

 if (ldrStatus >=300) {                // if the value is higher than 300,  LEDs is off
    digitalWrite (LED, LOW);
    Serial.println("it's bright");
  }

  else {           // if the value is lower than 300, both LEDs is on
      digitalWrite (LED, HIGH);
      Serial.println("it's dark");
      }
      Serial.println(ldrStatus);
 
}