// Define pins for the ultrasonic sensor
const int trigPin = 3;  // Trigger pin
const int echoPin = 2;  // Echo pin

// Define pin for the buzzer
const int buzzerPin = 7;

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
}

void loop() {
  // Clear the trigger pin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Send a 10 microsecond pulse to the trigger pin
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the duration of the pulse on the echo pin
  long duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in centimeters
  int distance = duration / 58.2;

  // Check if an object is within a certain range (e.g., 20 centimeters)
  if (distance < 200) {
    // If an object is detected within the specified range, sound the buzzer
    digitalWrite(buzzerPin, HIGH);
    delay(1000);  // Sound the buzzer for 1 second
    digitalWrite(buzzerPin, LOW);
  }

  // Print the distance to the serial monitor for monitoring
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Delay for a moment before taking the next reading
  delay(100);
}