Arduino Ultrasonic Distance Measurement Using HC-SR04

Introduction

This project demonstrates how to interface an HC-SR04 ultrasonic sensor with an Arduino Uno to measure distance accurately. Ultrasonic sensors are widely used in robotics, obstacle avoidance, parking systems, and IoT applications. The setup is simple, low-cost, and ideal for beginners.

Components Required

• Arduino Uno
• HC-SR04 Ultrasonic Sensor
• Breadboard
• Jumper Wires
• USB Cable (for Arduino programming)

How It Works (Simple Explanation)

• The Arduino sends a short pulse to the Trig pin of the ultrasonic sensor.
• The sensor emits ultrasonic waves.
• These waves bounce back after hitting an object.
• The Echo pin sends the time taken back to the Arduino.
• Arduino calculates distance using the speed of sound.

Arduino Code

#define trigPin 9
#define echoPin 10

long duration;
int distance;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  distance = duration * 0.034 / 2;

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

  delay(500);
}

Output

• Open Serial Monitor (9600 baud rate).
• Distance from the object will be displayed in centimeter.
• Move an object closer or farther to see real-time changes.

Applications

• Obstacle detection robots
• Smart parking systems
• Distance-based alarms
• IoT sensing projects

Conclusion

This project shows a clean and practical way to measure distance using Arduino and an ultrasonic sensor. It forms a strong foundation for robotics and automation-based projects on Hackster.