Ultrasonic Sensor Module (HC-SR04)

#define TRIG_PIN 9 // Trigger pin connected to digital pin 9
#define ECHO_PIN 10 // Echo pin connected to digital pin 10

void setup() {
	Serial.begin(9600);
	pinMode(TRIG_PIN, OUTPUT);
	pinMode(ECHO_PIN, INPUT);
}

void loop() {
	long duration, distance;

	// Send a 10-microsecond pulse to trigger the sensor
	digitalWrite(TRIG_PIN, LOW);
	delayMicroseconds(2);
	digitalWrite(TRIG_PIN, HIGH);
	delayMicroseconds(10);
	digitalWrite(TRIG_PIN, LOW);

	// Read the echo pulse duration
	duration = pulseIn(ECHO_PIN, HIGH);

	// Calculate the distance in cm
	distance = (duration / 2) / 29.1;

	// Display the distance
	Serial.print("Distance: ");
	Serial.print(distance);
	Serial.println(" cm");

	delay(1000); // Wait for a second before the next reading
}