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HC-SR04 Ultrasonic Sensor with Arduino UNO

HC-SR04 Ultrasonic Sensor with Arduino UNO
Atribot team

Written by

Atribot team

Last updated

June 18, 2026

Introduction

The HC-SR04 Ultrasonic Sensor is one of the most popular distance-measuring sensors used in Arduino projects. It works by transmitting ultrasonic sound waves and measuring the time taken for the echo to return after hitting an object.

In this tutorial, you will learn how to connect the HC-SR04 Ultrasonic Sensor to an Arduino UNO, upload the required code, and measure distances in centimeters using the Serial Monitor. This project is ideal for beginners interested in robotics, automation, and obstacle detection systems.

Components Required

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Item NameQtyAction
Arduino UNO
1
HC-SR04 Ultrasonic Sensor
1
USB Cable
1
Breadboardit is optional
1
Jumper Wires
4

Tools Required

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Item NameAction
Soldering Iron
Screwdriver

Software Required

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Item NameAction
Arduio IDE

Circuit Diagram

HC-SR04 Ultrasonic Sensor with Arduino UNO
HC-SR04 Ultrasonic Sensor with Arduino UNO

Source Code

HC-SR04_with_Arduino_UNO.inocpp
const int trigPin = 12;
const int echoPin = 11;

long duration;
float 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);
}

Step by Step Instructions

Step 1: Connect the Sensor

Make the following connections:

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HC-SR04

Arduino UNO

VCC

5V

GND

GND

TRIG

D12

ECHO

D11

Step 2: Open Arduino IDE

  1. Launch Arduino IDE.

  2. Connect Arduino UNO using USB.

  3. Select:

    • Board → Arduino UNO

    • Port → Correct COM Port

Step 3: Create a New Sketch

Create a new Arduino sketch and paste the provided code.

Step 4: Verify the Code

Click the Verify button to check for syntax errors.

Step 5: Upload the Code

Click Upload and wait until the upload process completes successfully.

Step 6: Open Serial Monitor

  1. Open Serial Monitor.

  2. Set baud rate to 9600.

  3. Place an object in front of the sensor.

You will see the measured distance displayed continuously.