Historically, we’ve used IR and ultrasonic sensors but [Makers Mashup] decided to use an ESP32-Cam as a motion ... s a 3D-printed enclosure to make the hardware assembly easy.

It’s based on a SparkFun ESP32 Thing, a very compact way ... an APDS-9930 proximity sensor, as well as four CNY70 IR proximity sensors on the bottom, used for line-following.

Would you believe it, the ESP32 popular Wi-Fi and Bluetooth chip has a built-in Hall effect sensor. Espressif Systems makes the chip, and its ESP32 data sheet has nearly no mention of the Hall sensor ...