// Define pin numbers
#define TRIG_PIN 9  // Trigger pin (connected to digital pin 9)
#define ECHO_PIN 10 // Echo pin (connected to digital pin 10)

long duration;  // Duration of the pulse in microseconds
int distance;   // Distance to the object in centimeters

void setup() {
  // Initialize the serial communication
  Serial.begin(9600);

  // Set the TRIG pin as an OUTPUT and ECHO pin as INPUT
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}

void loop() {
  // Send a 10 microsecond pulse to the TRIG pin to initiate measurement
  digitalWrite(TRIG_PIN, LOW);  // Ensure the trigger is LOW initially
  delayMicroseconds(2);  // Wait for 2 microseconds
  digitalWrite(TRIG_PIN, HIGH); // Send a HIGH signal to start the pulse
  delayMicroseconds(10); // Pulse width is 10 microseconds
  digitalWrite(TRIG_PIN, LOW);  // Set the TRIG pin LOW again

  // Measure the time it takes for the pulse to return
  duration = pulseIn(ECHO_PIN, HIGH);  // Measure the duration of the pulse on the ECHO pin

  // Calculate the distance in centimeters
  distance = (duration / 2) / 29.1; // Distance = (time / 2) * speed of sound (in cm/us)

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

  // Delay before taking another measurement
  delay(500);
}