1. Required Components

• 1 x Arduino Board (e.g., Arduino Uno)
• 1 x HC-SR04 Ultrasonic Sensor
• Jumper wires
• Breadboard (optional)
• USB cable to connect Arduino to PC

2. Wiring Instructions

Follow these steps to connect the HC-SR04 sensor to your Arduino:

• VCC: Connect to 5V on the Arduino.
• GND: Connect to GND on the Arduino.
• TRIG: Connect to digital pin 9.
• ECHO: Connect to digital pin 10.

3. How It Works

The HC-SR04 sensor emits ultrasonic waves through the TRIG pin and measures the time taken for the waves to reflect back to the ECHO pin. Using the speed of sound (343 m/s), the distance is calculated.

• digitalWrite(): Sends a signal to the TRIG pin to emit a pulse.
• pulseIn(): Measures the duration of the returning signal on the ECHO pin.
• Distance Formula: Distance in cm is calculated as (duration * 0.034 / 2), where 0.034 is the speed of sound in cm/µs.

4. Arduino Code

Copy and paste this code into the Arduino IDE:

// HC-SR04 Ultrasonic Sensor Pins
const int trigPin = 9;
const int echoPin = 10;

// Variables for storing the distance and pulse duration
long duration;
int distance;

void setup() {
  // Set up TRIG as output and ECHO as input
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  
  // Initialize Serial Monitor
  Serial.begin(9600);
}

void loop() {
  // Clear the TRIG pin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  
  // Send a 10-microsecond pulse
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the ECHO response time
  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in cm
  distance = duration * 0.034 / 2;

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

  // Wait before the next measurement
  delay(500);
}
            

5. Upload and Test

1. Connect your Arduino to your PC using the USB cable.
2. Open the Arduino IDE and paste the code above into a new sketch.
3. Select the correct board and port in the IDE.
4. Upload the code to your Arduino.
5. Open the Serial Monitor to view real-time distance measurements in centimeters.

6. Additional Tips

• Fine-Tune Sensitivity: Test in different environments to adjust for temperature or other factors affecting sound speed.
• Expand the Project: Integrate the sensor with an LCD display or control devices based on distance readings.
• Debugging: Use the Serial Monitor to verify the distance readings and troubleshoot wiring or code issues.

7. Conclusion

Congratulations! You’ve successfully created an ultrasonic distance measurement tool using the HC-SR04 and Arduino. This versatile sensor is a gateway to exciting projects in robotics, home automation, and obstacle detection systems.