volatile bool motionDetected=false;


void setup() {
  pinMode(13, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(2), detectMotion,RISING);
  Serial.begin(9600);
}

void loop() { 
  // put your main code here, to run repeatedly:
  if(motionDetected) {
    digitalWrite(13,HIGH);
    delay(5000);
    digitalWrite(13, LOW);
    motionDetected = false;
  }
}

void detectMotion() {
  motionDetected=true;
}