HC-SR04 Ultrasonic Distance Sensor

The HC-SR04 sends a 40 kHz ultrasonic pulse and times its echo to measure distance with about 3 mm resolution. Two digital pins (TRIG and ECHO) are all it needs, and libraries such as NewPing make it a five-line sketch on Arduino. It is the standard sensor for obstacle-avoiding robots, smart dustbins, parking sensors and contactless tank-level measurement.

Key features

• Range 2 cm – 400 cm with ≈ 3 mm resolution
• Simple TRIG/ECHO interface, works with any microcontroller
• 15° measuring angle
• 5 V supply, low current

Specifications

What's in the box

• 1 × HC-SR04 module

Ideal for

• Obstacle-avoiding robots
• Water tank level monitors
• Parking and proximity alarms

Good to know

• With 3.3 V boards (ESP32, ESP8266) use a voltage divider on the ECHO pin.