Ultrasonic Ranging Module HC-SR04 provides 2cm-300cm non-contact distance sensing capabilities, Ranging accuracy up to 3mm; module comprises an ultrasonic transmitter, a receiver, and a control circuit.
Basic operating principle:
1. IO port TRIG trigger ranging to at least 10us high-level signal
2. The module automatically sends eight 40khz square wave, automatically detects whether a signal return
3. A signal to return to a high output through the IO port ECHO high duration of the ultrasound wave from the transmitter to the time of the return. Test distance = (high level time * sound velocity (340M / S)) / 2;
Reliable, high performance, high accuracy, blind area within 2cm.
www.micropik.com/PDF/HCSR04.pdf










