User manual

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Chapter19 Distance sensor
Product features:
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:
 Using IO trigger for at least 10us high level signal,
 The Module automatically sends eight 40 kHz and detect whether there is a pulse signal
back.
 IF the signal back, through high level , time of high output IO duration is the time from
sending ultrasonic to returning. Test distance = (high level time×velocity of sound
(340M/S) /2
Wire connecting direct as following:
 5V Supply
 Trigger Pulse Input
 Echo Pulse Output