Instead, it relies on an ultrasonic distance sensor to detect a hand (or foot) waved in front of the door. An Arduino Leonardo runs the show, sounding a buzzer when the ultrasonic sensor is triggered.

This ultrasonic radar project is from [mircemk] who uses a small ultrasonic distance sensor attached to a rotating platform. A motor rotates it around a 180-degree field-of-view and an Arduino ...

By simply choosing a wireless sensor gateway for one’s favorite development platform (Arduino, Raspberry Pi or BeagleBone Black) and any of over 20 different types of wireless sensors, the ...