Keyboard Builders' Digest / Tips & Tricks
Partycrasher Micro & Xiao
Semickolon shared some updates to the FAK firmware, along with Partycrasher Micro, a Pro Micro drop-in replacement.
Published March 25, 2024
FAK, a keyboard firmware developed by semickolon aka mikoi14 for the cheap CH55x series MCUs, is now drop-in compatible with Pro Micro designs thanks to the newly implemented CH559L support.
Previously, FAK only supported CH552 chips (14 GPIOs at most), not enough for a Pro Micro replacement. Now, support has been added for CH559L which has over 40 GPIOs, way more than enough for a Pro Micro.
As a proof of concept and as a reference design, the author made Partycrasher Micro, a development board sporting the CH559L/CH558L with a footprint of a Pro Micro.
Compared to the Pro Micro, CH559L has a very minimal circuit that only requires TWO caps. No crystals, resistors, LDOs. This is amazing because this means diodeless 40% keyboards with integrated chip and very minimal circuit should now be possible with FAK! – semickolon.
True to the original concept of making keyboards as cheap as possible, the CH559L goes for $1.6 while the CH558L (virtually identical to CH559L except for flash size) goes for $1 on LCSC. You will likely find better deals elsewhere like on Aliexpress.
Other updates:
- Duplex matrix support has been added. This makes it possible to have up to 98 keys with just the 14 GPIOs on a CH552T.
- Rotary encoder support is also now implemented.
- There's repeat key, sticky layers, analogue to ZMK's macro_pause_for_release, and transparent layer exit. Check out the GitHub readme for more info!
Lastly, if you also wanna take a look at the Seeed Studio Xiao drop-in replacement for FAK, here's the Partycrasher Xiao.
Due to how minimal the circuits are for these hand-solderable dev boards, it feels oddly satisfying to just make one on my own pretty quickly then slap it on a keyboard. I never expected I'd make my own dev boards and firmware when I got into this hobby, but, yep – mikoi14.
Resources
Published on Mon 25th Mar 2024. Featured in KBD #159 (source).
Related
Micro Keyboard V3
Thomas Combe writes about his keyboard built for a 8-bit computer. Without a microcontroller.
USB-C Pro Micro size comparison
Fantastic-Onion4292 posted some photos of the new USB-C Pro Micro compared to the classic one.
Controller boards for CircuitPython
Controller boards for CircuitPython with Pro Micro footprint by SouthPawEngineer.
Arduino UNO Mini
The UNO is not your typical keyboard controller, but the anniversary edition is actually only 34.2mm x 26.7mm. Hmmm.
Rune controller
The Rune is a modular controller by Ziptyze (pics).