#define TRIG_PIN 17  // Trig pin of the ultrasonic sensor
#define ECHO_PIN 16  // Echo pin of the ultrasonic sensor
#define BUZZER_PIN 18 // Pin for the buzzer

void setup() {
  // Start serial communication for debugging
  Serial.begin(115200);
  
  // Set pin modes for the ultrasonic sensor
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  
  // Set pin mode for the buzzer
  pinMode(BUZZER_PIN, OUTPUT);
}

void loop() {
  long duration, distance;
  
  // Trigger the ultrasonic sensor
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Read the echo pulse duration
  duration = pulseIn(ECHO_PIN, HIGH);
  
  // Calculate distance in cm
  distance = duration * 0.034 / 2;
  
  // Print the distance (for debugging)
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  
  // If the distance is less than or equal to 12 cm, activate the buzzer
  if (distance <= 12 && distance > 0) {
    tone(BUZZER_PIN, 1000); // 1000 Hz tone
  } else {
    noTone(BUZZER_PIN); // Turn off the buzzer
  }

  // Wait for a short period before the next measurement
  delay(500);
}