This post is all about the Ultrasonic Sensor HC – SR04 mostly known as Sonar Sensor. I’ll explain how it works. Finally show how can you easily measure distance using this sensor.


The HC-SR04 ultrasonic sensor uses sonar to determine distance to an object like bats do. It offers excellent non-contact range detection with high accuracy and stable readings in an easy-to-use package. From 2cm to 400 cm or 1” to 13 feet. It’s operation is not affected by sunlight or black material like Sharp rangefinders are (although acoustically soft materials like cloth can be difficult to detect). It comes complete with ultrasonic transmitter and receiver module.

Sensor Features
Power Supply :+5V DC
Quiescent Current : <2mA
Working Current: 15mA
Effectual Angle: 15°
Ranging Distance : 2cm – 400cm or 1″ – 13ft
Resolution : 0.3 cm
Measuring Angle: 30 degree
Dimension: 45mm x 20mm x 15mm

Sensor Photo

Trig : Trigger (INPUT)
Echo: Echo (OUTPUT)

Connection Schematics:

Sensor | Arduino
VCC > 5V
Trig > D11
Echo > D12

I am assuming everyone is pretty much fimilar with Arduino Programming IDE. So, I am going to coding part directly.

int trigPin = 11;
int echoPin = 12;
int sound = 250;
void setup() 
 Serial.begin (9600);
 pinMode(trigPin, OUTPUT);
 pinMode(echoPin, INPUT);
void loop() 
 long duration, distance;
 digitalWrite(trigPin, LOW);
 digitalWrite(trigPin, HIGH);
 digitalWrite(trigPin, LOW);
 duration = pulseIn(echoPin, HIGH);
 distance = (duration/2) / 29.1;
 Serial.println(" cm");

Leave a Reply

Your email address will not be published. Required fields are marked *