The set-up process is very simple, and best understood by referring the wiring diagram. If everything goes right,you should see the burning eye of the red LED when there is no object in the safe-zone ...

40-KHz ultrasonic transmitter and receiver pair (40T/R-B/W) Schematic of the HC-SR04 module . Get to the point. In truth, my intent is not to provide a new translation of some well-worn “Arduino & ...