The ultrasonic ranging module, HC-SR04, provides 2 cm - 400 cm of non-contact measurement function and the ranging accuracy can reach up to 3 mm. The modules includes ultrasonic transmitters, receiver and control circuit. The basic principles:
- Using IO trigger for at least 10 μs high level signal
- The module automatically sends eight 40 kHz and detects whether there is a pulse signal back
- If the signal back is of a high level, the time of high output IO duration is the time from sending ultrasonic to returning.
Intro visual source: about ultrasonic transducer.
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