const int buzzer = 13;
const int pir = 11;
const int led = 12;
int motion;

void blink() {
  digitalWrite(led, HIGH);
  delay(300);
  digitalWrite(led, LOW);
  delay(300);
}

void setup() {
  pinMode(buzzer, OUTPUT);
  pinMode(pir, INPUT);
  pinMode(led, OUTPUT);
}

void loop() {
  motion = digitalRead(pir);
  if (motion == HIGH) {
    tone(buzzer, 262);
    blink();
  } else {
    noTone(buzzer);
    digitalWrite(led, LOW);
  }
}