Little Bird
Ultrasonic Distance Sensor HC-SR04
The HC-SR04 is a widely used ultrasonic distance sensor that measures distances from 2cm to 500cm (approximately 5 metres) with 1cm resolution. It works by e...
The HC-SR04 is a widely used ultrasonic distance sensor that measures distances from 2cm to 500cm (approximately 5 metres) with 1cm resolution. It works by emitting a 40kHz ultrasonic pulse, then measuring the time it takes for the echo to return — making it ideal for obstacle detection, range finding, and proximity sensing.
Send a 10μs trigger pulse and the module emits eight 40kHz ultrasonic bursts, then outputs a pulse proportional to the measured distance. If no object is detected, the output pin goes high for 38ms. A minimum cycle period of 50ms is recommended between measurements for accurate readings.
Specifications
- Power Supply: 5V DC
- Idle Current: <2mA
- Measurement Range: 2cm – 500cm
- Resolution: 1cm
- Effective Angle: <15°
- Ultrasonic Frequency: 40kHz
- Trigger Pulse: 10μs minimum
- Recommended Cycle Period: ≥50ms
Key Features
- Non-Contact Measurement – Ultrasonic ranging without physical contact
- Simple Interface – Single trigger pin and echo output; works with any microcontroller
- Wide Range – Detects objects from 2cm to 5 metres away
- Low Power – Under 2mA idle current
Ideal For
- Robot obstacle avoidance and navigation
- Drone low-altitude sensing
- Proximity detection and distance measurement projects
- Arduino and Raspberry Pi sensor projects
Jargon buster
Plain-language definitions for the technical terms used above.
- microcontroller
- A microcontroller is a small computer on a chip that runs your program and controls connected inputs and outputs. For this product, it is the part that reads buttons and sensors, drives the display and speaker, and communicates over Bluetooth.
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