const int trigPin = 9; // Trigger pin of the ultrasonic sensor
const int echoPin = 10; // Echo pin of the ultrasonic sensor
const int ledPin = 7; // LED pin
const int buzzerPin = 11; // Buzzer pin

void setup() 
{
  Serial.begin(9600); // Initialize serial communication
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
}

void loop() 
{
  long duration, distance;
  
  // Send ultrasonic pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the pulse duration on echo pin
  duration = pulseIn(echoPin, HIGH);

  // Calculate distance in cm
  distance = duration * 0.034 / 2;

  // Output distance to serial monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Check if the distance is below a threshold (adjust as needed)
  if (distance < 20) {
    // Turn on LED and buzzer
    digitalWrite(ledPin, HIGH);
    tone(buzzerPin, 1000); // You can adjust the frequency
  } else {
    // Turn off LED and buzzer
    digitalWrite(ledPin, LOW);
    noTone(buzzerPin);
  }

  delay(1000); // Adjust delay as needed for your application
}