After I’ve used my Lou1:e PCBs a while and I had some ideas for a PCB that was more suited for experimenting with crazy designs I started thinking about creating a new version. After talking to the user 4pplet on the Mechanical Keyboard Sweden discord I decided that STM32 had just what I wanted, a lot of extra IO pins and a somewhat beefy processor. I ended up using the STM32F072 since it requires very few external components, it even has a built-in oscillator.

Version 1.0 of the PCB

With all those extra IO ports, and using a four layer PCB it was fun to design. The result have one extra column of keys to the left and all unused IO ports are routed to the edge of the board for future use.

Admitted, version 1.0 is not perfect and I’ve already a version 1.1 halfway designed, but it had everything that I wanted just maybe not in the right place. It also had a misplaced capacitor that made it impossible to change boot mode without cutting a trace, but what is a PCB without botch-wires?