/members-area/personalblogs/b/blog/posts/measure-distance-using-ultrasonic-sensor-pi4j-java-raspberry-piwww.youtube.com/watch 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 princip...en-USTelligent Community 12