Pica40 v2

Split keyboard with 40 keys using XIAO controllers.

Pica pica - european (common) magpie

Features

40 keys - regular MX switches with hotswap sockets or soldered low-profile ChocV2 (with MX stem)
wired/wireless versions
aggressive stagger
slightly splayed for pinky columns

Wired version

XIAO RP 2040 controller
QMK firmware
USB-C connection between splits
rotary encoder on left side only (without click)
one status LED

Wireless version

XIAO BLE controller
ZMK firmware
on/off toggle
battery connectors

⚠️ Known issues

wired version is not fully compatible with low profile ChocV2 switches, 1.5U keycap cannot be bottomed out because of USB-C connector - to be fixed in new revision

Photos

wired version with 3d printed case

wired/wireless versions with Choc V2

Pica40 family - ChocV2 with low profile keycaps, ChocV2 with MT3 keycaps, Pica40 v1 with MT3 keycaps, regular switches and hotswap sockets

Firmware

QMK - available in main repository, also check my fork for most recent updates. Compiled file.
Vial - my fork. Compiled file.
ZMK - Source code, compiled left, compiled right, reset

Gerber files

PCB
Bottom plate
Top plate - reversible or full (for aluminum 1-layer plate)
Cover with hole - PCB cover over MCU and rotary encoder (recommended for wireless version)

Case files (STL - 3d printed)

Wired - Left with encoder hole, Right
Wireless - Left with encoder hole, Right with encoder hole
Universal (all holes - wired, wireless, encoders) - Left, Right
[Experimental] Bottom plate with cutouts for all components, replaces regular bottom plate to reduce overall height. Not compatible with 3d printed case (it's too tall). MX version - left, right, Choc V2 - left, right

Case files (DXF - for metal/acrylic)

Bottom, Bottom with tenting holes
Top
Cover - cover over MCU and rotary encoder space (for a half without an encoder), cover with hole - over MCU and rotary encoder (for a half with an encoder). Dark semi-transparent acrylic is recommended for those.

Bill of materials

PCBs
FR4/Metal/acrylic bottom plates
2 XIAO MCUs - RP2040 for wired version, nRF52840 for wireless
40 SMD SOD-123 1N4148 diodes
1 or 2 EC11/12 rotary encoder with knob
[Hotswap version] FR4/Metal top plates (and optionally covers) or 3d printed case
[Hotswap version] 40 hotswap sockets
[Hotswap version] 7mm M2 standoffs, 4-5mm M2 screws
[Soldered version] 6mm M2 screws, M2 nuts and washers
[Wired only] 2x USB-C 16pin connector
[Wireless only] 2x on/off toggle MSK-12C02
[Wireless only] 2x Li-Ion 3.7V battery

Build log

TODO

Changelog

V2.1 -⚠️ untested, located in a separate branch

added TRRS support
wired version supports rotary encoder on any side

V2

reworked to true split with two XIAO MCUs controllers
added splay to pinky columns
all case/pcb files are not compatible with V1

V1

split with single Pro Micro based MCU and handwired connection

AlGepe/pica40