The ish, yet another Corne-ish keyboard
Well, gotta learn kicad somehow and the Corne is one of my favorite boards. Like all keyboard people though, I have capital-T Thoughts about the Corne so why not learn kicad by tweaking the Corne.
To be clear before we get started, this is a Choc only build that is specifically designed for the nice!nano and ZMK (Technically you can slot an Elite-C or something into the PCB but the battery and lack of connectivity between the halves makes that a silly thing to do.)
Also to be clear, this is built with me, sungo, in mind. I will be super thrilled if other folks like it but this board is to make me happy and serve as a learning experience.
The first build is back from the manufacturers and I have thoughts. See the build notes for more info. But tl;dr: the v0.0.1 tag is perfectly serviceable but the battery hookup is slightly obnoxious. But it all works fine. I do suggest the corne v2 key switch plate, entirely because it’s built for Choc. The v3 plates work but are super tight getting the switches in.
A v0.1.0 design is underway.
AKA arbitrary rules I made up for myself
I put a bunch of text and links on the panelization. The board itself has a version number real small on the back under the MCU. The panelization text lets me convey the who and what and the version lets you know which board version you're holding in case it matters for the build guide. Otherwise, there are no brand markers on the finished board and there is no text visible on the top of the board once the MCU is in place.
There are very few traces on the top, just a few I needed to jump over traces that can't be moved. There is one trace on the top of left hand board that is the least complicated route for the reset line. I'd like to find another route for that but the other options are crazy complicated.
There are a lot of traces on the ish, by necessity, and keeping them all to the back led to a very crowded board. I did my best to limit the risk of crapping up traces on the back during the build but the area around the MCU is so tight that things aren't perfect.
There are no solder points on the top of the board. All the holes are masked off as well to keep anyone from getting a funny idea.
Keeping solder points and pads away from the edge led to a complication discussed below, needing the switches to be in different orientations on the separate halves.
All diodes do in fact go the same direction on each half.
Battery placement, plain and simple. If the nice!nano is chips-up, a 100mah battery fits perfectly under the MCU with a 4mm header easily obtained from Amazon. If the nice!nano is chips down, it does not.
This is the result of a few of the design principles. The Corne v2 and the Corne v3 end up putting diodes and solder pads on the edge of the board on one half because there's no where else for them to go. On the other side, one direction conflicts with the standoff annular ring placement. So, if I want to keep the diodes and pads away from the board edge and I don't want to move the annular rings, one half of the board must have switches that go the other direction. If I toss my rule against breaking v3 plate compatibility, I'll revisit this.
The original Corne is licensed under the MIT license so the ish is as well.
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Corne v3, kbd library © 2019-2022 foostan
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