Keyboard Builders' Digest / Projects
Pica40 v2
Evgenii Vilkov's Pica40 v2 is a wired/wireless split with splay and XIAO MCUs.
Published November 9, 2022
After the failure of V1, Evgenii Vilkov aka zzeneg came out with Pica40 v2, a split keyboard with slightly splayed pinky columns, added support for ChocV2 switches, and sporting Seeed's XIAO devboards.
So after my first attempt in designing a split keyboard failed a bit, I wanted to build an updated version. Lucky for me, around that time SeeedStudio announced a mechanical keyboard contest with two free PCBA boards. XIAO nRF52840 MCUs were already supported by ZMK so it was my chance to build a wireless keyboard. QMK almost released RP2040 support as well, so I wanted to keep wired compatibility too – zzeneg.
The name Pica is derived from Pica pica (European (common) magpie) which motif also appears on the PCB's silk screen.
According to the author, XIAO's MCUs have only 11 IO pins (theoretically you can use additional NFC pins on nRF52840) which is enough for the Pica's 5x4 matrix.
The wireless version has 2 free pins that are used for a rotary encoder. The wired version is left only with 1 free pin and it's also used for rotary encoder (only one and only on left side though).
It kinda was a stupid idea to connect two legs of a rotary encoder to different MCUs but in the end I made it work with custom QMK code – zzeneg.
Resources
All files are available on GitHub.
Published on Wed 9th Nov 2022. Featured in KBD #102 (source).
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