void setup() {
  // Initialize pins
  pinMode(2, INPUT);  // Set echoPin as an output
  pinMode(5, OUTPUT);   // Set echoPin as an input
  pinMode(7, OUTPUT);  // Set ledPin as an output

  Serial.begin(9600);  //Start serial communication for debugging
}

void loop() {
  // Generate a 10 microsecond pulse to start the measurement
  digitalWrite(5, LOW);
  delayMicroseconds(2);
  digitalWrite(5, HIGH);
  delayMicroseconds(10);
  digitalWrite(5, LOW);

  long duration = pulseIn(2, HIGH);     // Measure the duration of the pulse on the echoPin
  long distance = duration * 0.034 / 2; // Calculate the distance in cm
  Serial.print("Distance: ");           // Print the distance to the serial monitor
  Serial.print(distance);
  Serial.println(" cm");

  if (distance <= 20) {     // Check if the distance is less than 20 cm
    digitalWrite(7, HIGH);  // Turn on the LED
  } else {
    digitalWrite(7, LOW);   // Turn off the LED
  }
  delay(100); // Wait for a short period before taking the next measurement
}