keebs-nix

Self-contained Nix flake that builds ZMK firmware for my keyboards. Every keyboard's complete ZMK config is vendored into this repo under keyboards/, so the flake has no dependency on any external config repo and reproduces identical firmware to the upstream sources.

Keyboards — each links to its own README (keymap diagram, board/shield details, build & flash notes) and vendored config/:

• Ergonaut One — column-stagger split
• HolySwitch TK44 — unibody monosplit
• Mriya46 — column-stagger split
• Dao — 42-key column-stagger split (+ ZMK Studio)
• Charybdis Mini — 34-key column-stagger split

Built on top of zmk-nix.

Layout

keyboards/
  ergonaut-one/     config/ (+ build.yaml)   # board+shield split
  tk44/             config/ (+ build.yaml)   # single custom board
  mriya46/          config/ (+ build.yaml)   # split as two custom boards
  dao/              config/ (+ build.yaml)   # split as two custom boards (+ studio)
  charybdis-mini/   config/ (+ build.yaml)   # board+shield split
flake.nix

Each keyboards/<kb>/config/ is the keyboard's ZMK config dir (west.yml, boards/, keymaps, *.conf) copied verbatim from upstream.

Build

nix build               # all firmware → ./result (combined .uf2 dir)
nix build .#ergonaut-one
nix build .#ergonaut-one-reset
nix build .#tk44
nix build .#mriya46
nix build .#mriya46-reset
nix build .#dao
nix build .#dao-studio        # left half built with ZMK Studio enabled
nix build .#dao-reset
nix build .#charybdis-mini
nix build .#charybdis-mini-reset

nix build produces a result/ with stable names:

ergonaut_one_left.uf2
ergonaut_one_right.uf2
ergonaut_one_settings_reset.uf2
tk44.uf2
mriya46_left.uf2
mriya46_right.uf2
mriya46_settings_reset.uf2
dao_left.uf2
dao_right.uf2
dao_studio_left.uf2
dao_studio_right.uf2
dao_settings_reset.uf2
charybdis_mini_left.uf2
charybdis_mini_right.uf2
charybdis_mini_settings_reset.uf2

Flash

Double-tap reset on the keyboard, then:

nix run .#flash-ergonaut-one          # prompts for left, then right
nix run .#flash-ergonaut-one-reset
nix run .#flash-tk44
nix run .#flash-mriya46               # prompts for left, then right
nix run .#flash-mriya46-reset
nix run .#flash-dao                   # prompts for left, then right
nix run .#flash-dao-studio            # left half with ZMK Studio
nix run .#flash-dao-reset
nix run .#flash-charybdis-mini        # prompts for left, then right
nix run .#flash-charybdis-mini-reset

Dev shell

nix develop   # west + Zephyr ARM toolchain for manual `west build`

Editing keymaps / configs

Everything lives here now — edit the files under keyboards/<kb>/config/ directly (e.g. keyboards/tk44/config/tk44.keymap) and rebuild. No external repos are involved.

Keymap diagrams

Each keyboard's README.md embeds a layout diagram rendered by keymap-drawer into keyboards/<kb>/keymap-drawer/<kb>.svg. Regenerate them all after editing a keymap:

nix run .#draw-keymaps

It parses each config/<kb>.keymap and draws it against that keyboard's local physical-layout JSON (config/*.json), using the shared keymap-drawer/config.yaml.

ZMK version

Upstream the configs track revision: main, but ZMK main has migrated to Zephyr's Hardware Model v2, which renamed the boards these (HWMv1) configs use (seeeduino_xiao_ble → xiao_ble, nice_nano_v2 → nice_nano) and would not build them. So the vendored west.ymls pin ZMK to v0.3-branch (acfd8e5e…) + Zephyr 3.5 (dacab487…) — the same known-good, pre-HWMv2 revision zmk-nix's template uses. This keeps the HWMv1 board names and legacy custom-board definitions valid, avoids the huge hal_renesas module (added in later Zephyr), and is fully reproducible. To move to a newer ZMK you'd migrate the boards to HWMv2 and bump the pin.

Updating West deps

All four vendored configs ship a byte-identical west.yml, so a single zephyrDepsHash in flake.nix covers every keyboard (one West fetch is shared by all). Dao uses ZMK Studio and physical layouts, both already present on the pinned v0.3-branch, so it needs no separate fetch.

To refresh (after editing a west.yml, or to pull a newer ZMK):

1. set zephyrDepsHash to nixpkgs.lib.fakeHash in flake.nix,
2. run nix build .#tk44.westDeps (or any target),
3. copy the reported got: hash back into zephyrDepsHash.

The bundled nix run .#update from zmk-nix assumes a single west.yml at the repo root, which doesn't match this layout, so refresh manually as above.

Notes

• Self-contained: no flake inputs other than nixpkgs and zmk-nix. The keyboard configs are vendored, not referenced.
• The src suffix filter adds .c and .yaml on top of the upstream zmk-nix template list because the custom boards ship those (e.g. tk44.c, <board>.yaml) and they'd otherwise be dropped from the build source. It also keeps a board-level Kconfig (no suffix), which the Dao board ships for its DCDC option.
• Dao vendors its board from ergonautkb/ergonautkb-zmk-module (boards/arm/dao → keyboards/dao/config/boards/arm/dao) so the config is self-contained like the others, rather than pulling the module via west.yml.
• The shared West-deps fetch forces git to HTTP/1.1 (via GIT_CONFIG_* env) to survive GitHub's flaky HTTP/2 stream resets during the large Zephyr clone. Env vars don't affect a fixed-output derivation's hash, so this stays reproducible.
• To re-vendor a config after upstream changes, recopy keyboards/<kb>/config/ from the source repo/branch (the Mriya46 and TK44 configs come from different branches of the holyswitch repo).