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HC-SR04 ultrasonic level range finder

Ultrasonic ranging module HC - SR04 provides 2cm - 400cm non-contact measurement function, the ranging accuracy can reach to 3mm. The modules includes ultrasonic transmitters, receiver and control circuit. The basic principle of work:

  1. Using IO trigger for at least 10us high level signal
  2. The Module automatically sends eight 40 kHz and detect whether there is apulse signal back.
  3. IF the signal back, through high level , time of high output IO duration is the time from ending ultrasonic to returning.

Test distance = (high level time×velocity of sound (340M/S) / 2,

Frequency meter Frequency meter

Frequency meter

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Frequency Meter Code