const int trigPin = 9;  // Trig pin of the ultrasonic sensor
const int echoPin = 10; // Echo pin of the ultrasonic sensor

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  
  // Set the trigPin as an OUTPUT
  pinMode(trigPin, OUTPUT);
  
  // Set the echoPin as an INPUT
  pinMode(echoPin, INPUT);
}

void loop() {
  // Clear the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  
  // Set the trigPin HIGH for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  // Read the echoPin, return the sound wave travel time in microseconds
  long duration = pulseIn(echoPin, HIGH);
  
  // Calculate the distance in cm
  // Speed of sound wave divided by 2 (go and back) is 34300 cm/s
  // (duration * 0.0343) / 2 gives the distance in cm
  float distance = (duration * 0.0343) / 2;
  
  // Print the distance on the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  
  // Wait for a short period before the next measurement
  delay(1000);
}