const int trigPin = D4;   // Define the trigger pin (D4, GPIO 4)
const int echoPin = D5;   // Define the echo pin (D5, GPIO 5)

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

void loop() {
  long duration, distance_cm;

  // Send a short pulse to trigger the sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

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

  // Calculate distance from the pulse duration (in cm)
  distance_cm = duration / 58.0;

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

  delay(100);  // Wait for stability
}