Seeed Studio Studio Grove Ultrasonic Ranger - 40kHz PWM Distance Sensor Module

The module outputs a PWM signal on its single SIG pin. The pulse width (high time) of the echo signal is proportional to the measured distance. You can calculate the distance using the formula: Distance (cm) = (Pulse Width in microseconds * 0.034) / 2. Most code libraries handle this calculation automatically.

Yes. Unlike the HC-SR04, the Grove Ultrasonic Ranger is fully compatible with 3.3V logic levels. It operates from 3.2V to 5.2V, so you can connect its SIG pin directly to a Raspberry Pi GPIO pin without any voltage level shifters or additional circuitry.

The integrated microcontroller uses Time Division Multiplexing (TDM). You send a trigger pulse (>10µS) to the SIG pin. The module then takes control of the pin, emits the ultrasonic burst, listens for the echo, and outputs the resulting PWM distance measurement on the same pin. This design saves a microcontroller I/O pin.

For reliable detection, the target object's surface area should be at least 0.5 square meters and should be relatively smooth to effectively reflect the 40kHz sound waves. Highly absorbent or very small targets may not return a detectable echo.