5x5 STM32F1

narm · 22 Jan 2016, 14:45

https://github.com/dijkstrw/5x5

This is my first custom keyboard, a 5x5 cherry mx matrix based on the STM32F1 with libopencm3. During development I was mostly lurking here (Alternative controller experiments FTW), so it seems fitting to show it to you guys.

The project contains firmware, schematics and a board layout in kicad. The firmware supports

usb keyboard scancodes
bios boot and nkro
system / consumer codes
generation of mouse events
usb serial interface

It is intended as a personal development platform and stepping stone for a dual 6x6 or maybe 7x7. Currently the board can only be programmed by using a 6-pin TagConnect wired to a STM Discovery SWD/STLink programming port. The firmware is barebones but works great as a daily additional keyboard for me. (bank of fixed keys for virtual screen selection and media control)

: front.jpg (453.29 KiB) Viewed 3002 times

Any love for gojira?

flabbergast · 22 Jan 2016, 15:09

Awesome!

Daniel · 22 Jan 2016, 23:50

Nice project

I didn't know that it's possible to make transparent PCBs until now. What material is it?

nickw · 23 Jan 2016, 05:35

that's not transparent, he's just got no mask on it, the picture is in the tinning of the board. mirrorish.

Ordinary FR4 pcb does let a lot of light through when there's no copper on either side though.

narm · 23 Jan 2016, 11:36

Daniel wrote: Nice project I didn't know that it's possible to make transparent PCBs until now. What material is it?

Ha -- After looking again at the picture I can see how you would think that. nickw has the right of it though, this is FR4 with red soldermask and HASL finish.

nickw wrote: Ordinary FR4 pcb does let a lot of light through when there's no copper on either side though.

The area near the usb connector on top has no top/bottom fills, and the 2nd Gojira glyph removes the soldermask as well there, so that gives an idea of what the base FR4 looks like from pcbway.

narm · 23 Jan 2016, 13:02

Daniel wrote: I didn't know that it's possible to make transparent PCBs until now. What material is it?

So thanks for that -- you got me wondering too if transparent was possible. It seems that there a couple of boardhouses that do transparent soldermask. All the cheap and cheerfull boardhouses do not seem to support it though.

aaron · 24 Jan 2016, 00:49

Nice Board!
Can you post some more pictures?

narm · 26 Jan 2016, 21:47

aaron wrote: Can you post some more pictures?

Sure. Backside of the board:

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Quick shots of the stuff on my bench now. I've started using one as an extra keyboard, so I need a new set of two for my board-to-board experiments. That is the purpose of the two footprints on the back to the sides.These have been wired up for I2C, and although I foobarred the firewire footprint, it will fit with some budgery.

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