Technical Specification
Power Supply :+5V DC
Quiescent Current :3mA
Working Current: Effectual Angle: Ranging Distance :2cm - 450 cm
Resolution :0.3 cm
Measuring Angle:30 degree
Note: The module should be inserted Fortunately, the circuit board re-energized, and avoid the high malfunction, if they have re-energized before they solve.

HC-SR04 Themodule works
IO trigger ranging to at least 10us high signal;
Module automatically sends eight 40kHz square wave, automatically detect whether a signal return;
The signal to return, a high IO output, high duration of
Test distance = ((Duration of high level)*(Sonic :340m/s))/2