PIR Sensor HC-SR501

// PIR Sensor HC-SR501 - canonical beginner example
// Reads the sensor output on D2 and prints motion status to Serial Monitor.

const int pirPin = 2;

void setup() {
  pinMode(pirPin, INPUT);
  Serial.begin(9600);
  while (!Serial) {
    ;
  }
  Serial.println("PIR sensor warming up... give it about 30-60 seconds.");
}

void loop() {
  int motion = digitalRead(pirPin);

  if (motion == HIGH) {
    Serial.println("Motion detected!");
  } else {
    Serial.println("No motion.");
  }

  delay(500);
}