Looking to improve on this simplistic interface, [Sören Beye] tacked an ESP8266 to the board so it can broadcast sensor readings out over MQTT. Just three wires link the ESP8266 to the PCB.

You have an ESP8266 board like the Wemos D1 ... From there, you have examples on using deep sleep, do pushbutton or sensor-driven wakeup, manage WiFi, and even read the battery voltage ...

At its core, it is just an ESP8266, a cheap simple Wi-Fi chip that is in tons of tech. If you have Wi-Fi light bulbs, you probably have several of these chips in your home right now. Devices like ...