Tech Support: services@elecfreaks.com Ultrasonic Ranging Module HC - SR04Product 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: (1) Using IO trigger for at least 10us high level signal, (2) The Module automatically sends eight 40 kHz and detect whether there is a pulse signal back. (3) 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 0V Ground Electric ParameterWorking VoltageDC 5 VWorking Current15mAWorking Frequency40HzMax Range4mMin Range2cmMeasuringAngle15 degreeTrigger Input Signal10uS TTL pulseEcho Output SignalInput TTL lever signal and the range inproportionDimension45*20*15mm