Ultrasonic Sensor, HC-SR04, Distance Measurement up to 3 m

The HC-SR04 ultrasonic distance module has a high precision of up to 3 mm and can easily be accessed by common microcontrollers and Arduino.

The board has two power lines (VCC, GND) and two lines for initiating a meaurement and reading the distance. A HIGH signal or single pulse on the "Trig" pin triggers a measurement and the module sends a 40 kHz pulse. The returning signal is detected and the output line "Echo" is set to HIGH for the time t. The distance is proportional to the time t and can be calculated with this formula:

distance in m = t in s * speed of sound (ca. 340 m/s) / 2

Specification: