const int PIR_SENSOR_PIN = 12;  // PIR sensor input pin
const int RELAY_PIN = 13;       // Relay output pin

void setup() {
  pinMode(PIR_SENSOR_PIN, INPUT);  // Initialize PIR sensor as input
  pinMode(RELAY_PIN, OUTPUT);      // Initialize relay as output
  digitalWrite(RELAY_PIN, LOW);    // Start with relay off
}

void loop() {
  int pirValue = digitalRead(PIR_SENSOR_PIN);  // Read PIR sensor value
  
  if (pirValue == HIGH) {  // If motion is detected
    digitalWrite(RELAY_PIN, HIGH);  // Turn on relay
  } else {  // If no motion is detected
    digitalWrite(RELAY_PIN, LOW);  // Turn off relay
  }

  delay(100);  // Small delay to avoid bouncing
}