Suutari20 (DIY modular macro keyboard)

A modular macro keyboard built around a Raspberry Pi Pico (or any pin-compatible RP2040 clone): a main board runs open-source firmware, and separate key/encoder modules plug into it over ordinary 3.5 mm audio jacks, from a plain mono (TS) plug up to a full four-conductor TRRS. MIT licensed, 18 stars / 0 forks at ingest, by GitHub user Squalius-cephalus — a handle with no other identifying information surfaced, so this page treats the project as the entity rather than paging a person behind it.

What it is made of

Main board: custom PCB (Gerber and KiCad files in the repo) plus a Pico/RP2040 clone
Case: 3D-printed, source files included
Fasteners: four M2×L3×OD3 heat-set inserts, four M2 bolts
Connectors: eight PJ-320A 3.5 mm audio sockets
A splitter module (its own small PCB and case) fans one TRRS port out to three mono jacks, for modules — footswitches, single buttons — that only need one conductor
Firmware: QMK with Vial layered on top, so key layouts are remapped from a graphical tool rather than by recompiling and reflashing

Module variety shown in the repo's photos includes a single-key module, a three-key module, and a module built around an EC11 rotary encoder — the modularity is in the connector, not in a fixed module catalog.

Reuse instead of a from-scratch design

The PCB does not draw its own key-switch and jack footprints. The README credits two other open-hardware keyboard projects for them: ScottoKeebs and the kbd library (foostan/kbd). Suutari20 is built by importing parts of two other people's published designs, the hardware equivalent of pulling in a software library rather than writing the routine again. See open-hardware for why this is a distinct pattern from the three motivations already on that page.

An honest, unfinished source

The README's own TODO list is "add images" and "add more module info," and it says outright that a YouTube video ("Modular Macro Keyboard - Suutari20") currently holds more information than the written documentation. The project's GitHub wiki has seven pages (Home, Getting started, Build Guide, Designing your own module, Firmware upload, MX Module, TRRS Splitter); five of them are one-revision placeholders whose only content is a photo and the sentence "more information coming soon." No pinout, no TRRS conductor assignment, and no module design rules are published anywhere in text at the time of this ingest — a reader who wants either has to watch the video. This is recorded as a property of the source, not a defect to paper over: a small, active, single-maintainer hobby project that is still being written down.

Tier

T1. Under this spoke's standing rule (../QUALITY.md → tier by the claim, not the URL), a project repository is primary for its own artifact facts — here, the bill of materials, the connector choice, the firmware stack and the licence — and none of that is a performance or capability claim needing independent checking. The same reasoning tiered the-open-book-ereader and flopperziro T1 despite both being unreviewed hobby projects; popularity (18 stars against FlopperZiro's 1.8k) does not enter the tier. What the grade does not cover is completeness: most of the design is not written down yet (see above), which is a gap-relevance note, not a tier demotion.

Cross-spoke context

The firmware angle — QMK with Vial for graphical remapping — also touches ../foss-applications-wiki (open-source keyboard/firmware tooling). The dominant substance of this source is the physical, modular, open-hardware device, which is this spoke's domain, so the ingest lands entirely here; the firmware-tooling facet is recorded as cross-spoke context only, not ingested there.

open-hardware · raspberry-pi-pico · microcontroller · embedded-systems · the-open-book-ereader · flopperziro · synthesis