int RELE =3;
int PIR=2;
int ESTADO=0;

void setup() {
  // put your setup code here, to run once:
  pinMode(PIR, INPUT);
  pinMode(RELE, OUTPUT);
  delay(20000);
}

void loop() {
  // put your main code here, to run repeatedly:
  ESTADO = digitalRead(PIR);
  if(ESTADO == HIGH){
    digitalWrite(RELE,LOW);
    delay(4000);
  }else{
    digitalWrite(RELE,HIGH);
  }  
}