HC-SR04 Ultrasonic Distance Sensor Module ( 2cm to 400cm )

The HC-SR04 Ultrasonic Distance Sensor uses sound waves to measure the distance between the module and a nearby object. Therefore, it provides a practical solution for robots, obstacle detection, level monitoring, and automation projects.

The module includes an ultrasonic transmitter, receiver, and control circuit. Moreover, its four-pin interface makes it easy to connect to Arduino and other development boards.

Key Features

• Measures distance without physical contact
• Offers a measurement range from 2cm to 400cm
• Provides accuracy up to 3mm under suitable conditions
• Uses 40kHz ultrasonic signals
• Includes separate Trigger and Echo pins
• Works with Arduino and many microcontrollers
• Offers fast and repeatable distance readings
• Requires only one digital input and one digital output
• Compact and lightweight design

Technical Specifications

• Model: HC-SR04
• Sensor Type: Ultrasonic Distance Sensor
• Operating Voltage: 5V DC
• Operating Current: Approximately 15mA
• Measurement Range: 2–400cm
• Ranging Accuracy: Up to 3mm
• Ultrasonic Frequency: 40kHz
• Detection Angle: Approximately 15°
• Trigger Signal: HIGH pulse of at least 10µs
• Output Signal: TTL Echo pulse
• Dimensions: Approximately 45 × 20 × 15mm

Pin Configuration

• VCC: Connect to a regulated 5V supply
• TRIG: Receives the measurement trigger pulse
• ECHO: Outputs a pulse proportional to the measured distance
• GND: Connects to the circuit ground

How It Works

First, the controller sends a HIGH pulse of at least 10µs to the TRIG pin. The module then transmits eight ultrasonic pulses at 40kHz.

Next, the receiver waits for the reflected sound. The ECHO pin remains HIGH for the time required by the sound to travel to the object and return.

Calculate the distance with this formula:

Distance = Echo Time × Speed of Sound ÷ 2

For a simple centimetre calculation at room temperature:

Distance in cm ≈ Echo Time in µs ÷ 58

Applications

The HC-SR04 suits many electronics projects, including:

• Robot obstacle detection
• Distance-measuring devices
• Automatic parking prototypes
• Tank and container level monitoring
• Security and proximity systems
• Smart bins and automatic doors
• Arduino and STEM projects
• Industrial automation prototypes

Important Notes

• Power the standard HC-SR04 module with 5V.
• The ECHO pin can output 5V logic.
• Use a voltage divider or level shifter with 3.3V controllers.
• Connect all devices to a common ground.
• Soft, narrow, curved, or angled objects may reduce measurement reliability.
• Temperature and air conditions can affect the speed of sound.
• This standard module is not waterproof.
• Allow enough time between measurements to prevent false echoes.

Package Includes

• 1× HC-SR04 Ultrasonic Distance Sensor Module