const int PIRsensor = 2;
const int LED = 3;

void setup() {
  pinMode (PIRsensor, INPUT);
  pinMode (LED, OUTPUT);
  digitalWrite (LED, LOW);
}

void loop() {
  int value = digitalRead (PIRsensor);
  if (value == HIGH){
    digitalWrite (LED, HIGH);
    delay (500);
  }
  else{
    digitalWrite (LED, LOW);
  }
}