#define LdrPin A0
#define RelayPin 2
int lumen = 0;

void setup() {
  pinMode (LdrPin,INPUT);
  pinMode (RelayPin, OUTPUT);
  digitalWrite(RelayPin, LOW);
  Serial.begin(9600);
}

void loop() {
  lumen = analogRead(LdrPin);
  if (lumen <= 511) {
    digitalWrite(RelayPin, LOW);
  } else if (lumen >= 512 ) {
    digitalWrite(RelayPin, HIGH);
  }
  Serial.println(lumen);

}