At the beginning of my keyboard journey I was sure to make a standard 100% layout, now, as I got more into that topic, I figured out that I don't want that any more and maybe people who are more into mechanical keyboard can understand.

So ultimately, I decided to go for a split keyboard with 36 keys plus one encoder on one side. That is about the maximum I can operate with a RP2040 without the need of a port extender.

As I already made my first steps in KiCad with the PolyKB Atom, I felt confident enough that this works out.

Maybe I should have done some more studies on ergonomics, but we all have to start somewhere, so this how the left side of my keyboard will look like:

As you might be able to see, the RP Pico board can be soldered to the PCB on the backside (unfortunately it only has a Micro USB as we know :/ ) and I decided to use an RJ12 jack to connect the two boards.

I know a TRRS jack would be sufficient, but it feels a bit... "strange" to power the second board with that, as the power "pins" would be totally unprotected when disconnecting in operation. Also, I was not sure if I need another pin for bi-directional communication (maybe not, but we will see)

For the keyboard plate I'm using aluminium as I can order it together with the PCB from JLCPCB (as they are making aluminium PCBs as well) and I can design it in KiCad as well, no need for anything else.

Since it is possible to add a silk screen to the aluminium plate I wanted to have an appropriate design for my project: True to my goal to make a keyboard that speaks multiple languages I found the perfect fit, the oldest piece of multilingual history - the Rosetta Stone.

As I wanted to have the shiny side on top, I designed the plate with the silk screen directly on the front aluminium and the solder mask on the back (where you could apply another silk screen).

JLCPCB doesn't make guarantees about the quality of the silk screen on that side but I will find out :)