Ultrasonic Distance Sensor HC-SR04

The HC-SR04 is one of the most popular and affordable ultrasonic distance sensors for robotics and electronics projects. It uses sound waves to measure distance, making it perfect for obstacle avoidance, proximity detection, and level sensing applications.

Simply send a trigger pulse and measure the echo return time to calculate distance. Works with Arduino, Raspberry Pi, micro:bit, and virtually any microcontroller.

Key Features

• 2cm to 500cm Range – Wide detection range for most applications
• 1cm Resolution – Accurate distance measurements
• Low Power – Under 2mA quiescent current
• Simple Interface – Just trigger and echo pins
• 5V Operation – Standard logic level

Specifications

• Power Supply – 5V DC
• Quiescent Current – <2mA
• Detection Range – 2cm to 500cm
• Resolution – 1cm
• Effective Angle – <15°
• Ultrasonic Frequency – 40kHz
• Trigger Pulse – 10µs minimum
• Cycle Period – 50ms minimum recommended

How It Works

Send a 10µs trigger pulse to initiate measurement. The sensor transmits eight 40kHz ultrasonic pulses and listens for the echo. The echo pulse width is proportional to the measured distance. If no obstacle is detected, the echo pin goes high for 38ms.

Ideal For

• Robot obstacle avoidance
• Proximity and presence detection
• Liquid level sensing
• Parking sensors
• Drone altitude sensing