I just finished building a Corne and Sofle split keyboards recently and during my research into what microcontrollers to use I found there was so much more out there now than when I first got into this hobby.
A few years ago the choice for a microcontroller (which I’ll refer to as an ‘MCU’ for the rest of this post) was between a Teensy or a Pro Micro or a clone of some sort. Now there are a ton of options to choose from.
Since I live in Canada my choices for sourcing an MCU is rather limited compared to living in the USA. The usual avenue for buying MCUs is Amazon, Digi-Key, Mouser or a Canadian vendor of keyboards/keyboard parts off of Alex Otos’ vendor list. Of course the cheapest route is to buy at least a few from AliExpress and wait a few weeks to a month or more for it to arrive.
The older Pro Micro MCUs and clones were notorious for breaking at the Micro USB ports after just a handful of times of plugging and unplugging the cable.
I didn’t want to worry about this especially since I’ll be doing a lot of plugging/unplugging in the beginning while I sort out my keymap. So I went to AliExpress and ordered Pro Micro clones with a USB C port.
When ordering from AliExpress I like to pay through PayPal while using my credit card as a funding source so I have two avenues of recourse in case of any issues first through PayPal and second through my bank/credit card issuer. Thankfully I didn’t need to worry about that this time around.
When sourcing MCUs from AliExpress and building a keyboard that normally requires a Pro Micro, you’ll want to make sure the a) pinouts are the same and b) the physical dimensions are close to or the same as the original Pro Micro otherwise you run the risk of the MCUs you ordered not working for your specific build. This applies only to keyboards that were designed to run off Pro Micros though–if you’re hand wiring a keyboard or designing your own from scratch obviously this won’t affect you but you’ll still want to take it into consideration.
There’s a great list of the most common microcontrollers over on the Golem project run by Tamas Dovenyi of kbd.news.
If you’re even slightly interested in keyboards you owe it to yourself to subscribe to his monthly Keyboard Builder’s Digest. It’s really great content for keyboards nerds and hobbyists. I’m not affiliated with him in any way but he’s an awesome guy and he puts out great content and I love the work.
I’m waiting on some wireless MCUs to arrive this week so I can build and try out a super low-profile Corne build with Choc switches.
Stay tuned for that build which I’ll share here and over on /rmk and the /r/ergomechkeyboards subreddits.