// Define pins for Ultrasonic Sensor
const int trigPin = 9;   // Trigger pin of the ultrasonic sensor
const int echoPin = 10;  // Echo pin of the ultrasonic sensor
const int ledPin = 13;   // Pin for the LED (optional for object detection)

void setup() {
  // Initialize the trigger and echo pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  
  // Initialize the LED pin (optional)
  pinMode(ledPin, OUTPUT);
  
  // Start serial communication for debugging
  Serial.begin(9600);
}

void loop() {
  // Send a 10us pulse to the trigger pin to start the measurement
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the time duration between sending and receiving the signal
  long duration = pulseIn(echoPin, HIGH);

  // Calculate the distance (Speed of sound is ~343 m/s)
  // Distance in cm = duration / 58.2
  float distance = duration / 58.2;

  // Print the distance in the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Optional: Light up the LED if the object is within 10 cm
  if (distance <= 10) {
    digitalWrite(ledPin, HIGH);  // Turn on LED if object is close
    Serial.println("Object detected within 10 cm!");
  } else {
    digitalWrite(ledPin, LOW);   // Turn off LED if object is far
  }

  // Small delay before the next measurement
  delay(500);
}