// Define the pins connected to the HC-SR04 sensor
const int trigPin = 27; // Trigger pin connected to Arduino digital pin 9
const int echoPin = 26; // Echo pin connected to Arduino digital pin 10

// Define variables for duration and distance
long duration; // Variable to store the duration of the sound wave travel
int distanceCm; // Variable to store the calculated distance in centimeters

void setup() {
  // Initialize serial communication at 9600 baud rate
  Serial.begin(9600);

  // Set the trigger pin as an output
  pinMode(trigPin, OUTPUT);

  // Set the echo pin as an input
  pinMode(echoPin, INPUT);
}

void loop() {
  // Clear the trigger pin by setting it low for a short period
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Set the trigger pin high for 10 microseconds to send out a pulse
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

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

  // Calculate the distance in centimeters
  // Speed of sound is approximately 0.034 cm/microsecond.
  // We divide by 2 because the sound travels to the object and back.
  distanceCm = duration * 0.0341 / 2;

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

  // Add a small delay between measurements
  delay(1000);
}