2021-12-11: Wall switch control module

Recently, I was requested to design and build a small series of modules for wall switch control. They are going to be integrated into the switch junction boxes to make them “inteligent”. The control is carried out over a CAN bus and they are able to drive 4 individual LEDs for backlight, drive one WS281x programmable LED string and read 4 igital inputs and two NTC thermistors.

Requirements were given, the main challenge was to fit all the required components onto a board smaller than 40x40 mm and still manage to include reasonable input/output protections, maintain high power supply efficiency and low idle power consumption and make the thing easy to manufacture and use.

The control module is built around the STM32G431 microcontroller on a 4 layer board. Prototypes were submitted for manufacturing at Aisler on 2021-12-10. Some pictures of the layout and 3D render: