Ultrasonic Sensor (HC-SR04)

Overview

The HC-SR04 ultrasonic sensor measures distance by emitting ultrasonic sound waves and calculating the time taken for the echo to return. It is widely used in obstacle detection, robotics, and level monitoring applications due to its reliability, accuracy, and ease of interfacing.

Technical Specifications

Operating Voltage: 5 V DC

Operating Current: 15 mA

Frequency: 40 kHz

Range: 2 cm – 400 cm

Accuracy: ±3 mm

Measuring Angle: 15°

Trigger Pulse: 10 µs TTL pulse

Echo Pulse: 150 µs – 25 ms

Key Features

Non-contact distance measurement
High accuracy and stable performance
Wide detection range up to 4 m
Simple digital trigger and echo interface
Low power consumption
Compact and lightweight module
No moving parts for long life
Unaffected by ambient lighting

Wiring Diagram

Basic Connection (Arduino Uno)

HC-SR04 Pin → Arduino Pin

VCC → 5V

GND → GND

Trig → Digital Pin 9

Echo → Digital Pin 10

Common Applications

Robot Navigation

Obstacle detection and autonomous movement

Distance Measurement

Non-contact object distance sensing

Security Systems

Motion and proximity detection

Level Monitoring

Water tank and liquid level sensing

Quick Info

Difficulty: Beginner

Price Range: ₹70–200

Interface: Digital (Trigger / Echo)

Compatible Boards

Sample Code

#define trigPin 9
#define echoPin 10

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

void loop() {
  long duration;
  int distance;

  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);
}