zmk-config

This is my personal ZMK firmware configuration. It is ported from my QMK configuration, which in turn is heavily inspired by Manna Harbour's Miryoku layout.

Key features

• simple macro-implementation of combos and keymap to fit different physical keyboards¹
• home-row mods on base layer, sticky mods on Nav and Num layers
• most symbols can be accessed from the base layer via combos
• sticky shift on right thumb, double-tap activates caps-word
• backspace morphs into delete when shifted
• full numpad-layer with arithmetic operators (= via combo) and Esc, Enter, Tab on left hand (can be numlocked via W + P combo, ideal for data entry and right-handed mouse)
• unicode-layer with Greek letters for mathematical typesetting (implemented via preprocessor macros²)

A few thoughts on the combo setup

The combo layout is guided by two goals: (1) put all combos in easy-to-access locations, and (2) make them easy to remember. Specifically:

• the top vertical-combo row is almost equivalent to the symbols on standard number rows, making them easy to remember
• the bottom vertical-combo row is set up symmetrically to facilitate memorization (subscript _ aligns with superscript ^; minus - aligns with +; division / aligns with multiplication *; logical-or | aligns with logical-and &; backslash \ aligns horizontally with forward slash /)
• parenthesis, braces and brackets in symmetric positions
• ! and ? are on home-row position for prime access
• a numlock shortcut (on W + P) for one-handed data entry
• shortcuts for cut (on X + D), copy, and paste on the left-hand side for right-handed mouse usage

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1. I use a 36-key layout per default. Additional thumb keys can be configured with the EXTRA_BOT_L and EXTRA_BOT_R macros. Additional "middle-keys" can be configured with the EXTRA_MID macro (see planck_rev6.keymap for an example).

   In order to consitently configure combos and positional hold-taps across keyboards with different physical key specifications, I use a set of "virtual location" macros which map key-positions in the layout to physical locations on the shield. These macros follow a common naming convention, starting with LT0 for the first key on the Left Top-row and ranging to RB4 for the last key on the Right Bottom-row. They need to be defined in the shield-specific keymap-file before sourcing the common base.keymap. ↩︎

2. This is my attempt at a simple user-space solution until unicode is natively supported. Check out unicode.dtsi for details and read my write up here for a few more pointers and some caveats. ↩︎