#define trigPin 13
#define echoPin 12
const int buzzer = 11;
const int ledPin = 10;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  long duration, distance;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration / 2) / 29.1; // Calculate distance in centimeters
  delay(500);

  if (distance >= 40) {
    digitalWrite(buzzer, HIGH);
    digitalWrite(ledPin, HIGH); // Alarm if an object is detected within 40 cm
  } else {
    digitalWrite(buzzer, LOW);
    digitalWrite(ledPin, LOW); // No intruder detected
  }
}