150 lines
8.1 KiB
Markdown
150 lines
8.1 KiB
Markdown
# urob's zmk-config
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This is my personal [ZMK firmware](https://github.com/zmkfirmware/zmk/) configuration.
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It is ported from my QMK configuration, which in turn is heavily inspired by Manna Harbour's
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[Miryoku layout](https://github.com/manna-harbour/miryoku).
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## Key features
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- clean keymap + unicode setup using helper macros from
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[zmk-nodefree-config](https://github.com/urob/zmk-nodefree-config)
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- keymap and combo setup portable across different physical layouts
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- ["timeless" homerow mods](#timeless-homerow-mods) on the base layer;
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sticky mods on other layers
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- combos replacing the symbol layer
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- sticky shift on right thumb, double-tap activates caps-word
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- shift + space morphs into dot + space + sticky-shift
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- shift + backspace morphs into delete
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- "Greek" layer for mathematical typesetting
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## Timeless homerow mods
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Homerow mods [are great](https://precondition.github.io/home-row-mods). But they can
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require some finicky timing: In its most naive implementation, in order to produce a "mod",
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they must be held *longer* than `tapping-term-ms`. In order to produce
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a "tap", they must be held *less* than `tapping-term-ms`. This requires very consistent
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typing speeds that, alas, I do not possess. Hence my quest for a "timeless" HRM
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setup.[^1]
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Here's what I have ended up with: A "timeless" HRM setup with virtually no misfires and
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yet a fluent typing experience with mostly no delays.
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Let's suppose for a moment we set `tapping-term-ms` to something ridiculously large, say
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5 seconds. This makes the configuration "timeless". But it also creates two
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problems: (1) In order to get a "mod" we now have to hold the HRM keys for
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what feels like eternity. (2) In normal typing, when tapping keys, there can be
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long delays between the press of a key and the time it appears on the screen. Enter my
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two favorite configuration options:
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* To address the first problem, I use ZMK's `balanced` flavor, which produces
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a "hold" if another key is both pressed and released within the tapping-term. Because
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that is exactly what I normally do with HRMs, there is virtually never a need to wait
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past my long tapping term (see below for two exceptions).
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* To address the typing delay, I use ZMK's `global-quick-tap` property, which
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immediately resolves a HRM as "tap" when it is pressed shortly *after* another key
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has been tapped.[^2] This all but completely eliminates the delay when typing.
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This is almost perfect, but there's still a few rough edges:
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* When rolling keys, I sometimes unintentionally end up with "nested" key
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sequences: `key 1` down, `key 2` down and up, `key 1` up. Given the `balanced` flavor,
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this would falsely register `key 1` as a mod. To prevent this, I use ZMK's "positional
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hold-tap" feature to force HRMs to always resolve as "tap" when the *next* key is on
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the same side of the keyboard. Problem solved.
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* ... or at least almost. The official ZMK version for positional-hold-taps performs the
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positional check when the next key is *pressed*. This is not ideal, because it
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prevents combining multiple modifiers on the same hand. To fix this, I use a small
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patch that delays the positional-hold-tap decision until the next key's *release* ([PR
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#1423](https://github.com/zmkfirmware/zmk/pull/1423)). With the patch, multiple mods
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can be combined when held, while I still get the benefit from positional-hold-taps
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when keys are tapped.
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* So far, nothing of the configuration depends on the duration of `tapping-term-ms`. In
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practice, there are two reasons why I don't set it to infinity:
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1. Sometimes, in rare circumstances, I want to combine a mod with a alpha-key *on
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the same hand* (e.g., when using the mouse with the other hand). My positional
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hold-tap configuration prevents this *within* the tapping term. By setting the
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tapping term to something large but not crazy large (I use 280ms), I can still
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use same-hand `mod` + `alpha` shortcuts by holding the mod for just a little while
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before tapping the alpha-key.
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2. Sometimes, I want to press a modifier without another key (e.g., on Windows,
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tapping `Win` opens the search menu). Because the `balanced` flavour only
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kicks in when another key is pressed, this also requires waiting past
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`tapping-term-ms`.
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Here's my configuration (I use a bunch of [helper
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macros](https://github.com/urob/zmk-nodefree-config) to simplify the syntax, but they
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are not necessary):
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```C++
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/* use helper macros to define left and right hand keys */
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#include "../zmk-nodefree-config/keypos_def/keypos_36keys.h" // keyposition helpers
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#define KEYS_L LT0 LT1 LT2 LT3 LT4 LM0 LM1 LM2 LM3 LM4 LB0 LB1 LB2 LB3 LB4 // left-hand keys
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#define KEYS_R RT0 RT1 RT2 RT3 RT4 RM0 RM1 RM2 RM3 RM4 RB0 RB1 RB2 RB3 RB4 // right-hand keys
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#define THUMBS LH2 LH1 LH0 RH0 RH1 RH2 // thumb keys
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/* left-hand HRMs */
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ZMK_BEHAVIOR(hml, hold_tap,
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flavor = "balanced";
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tapping-term-ms = <280>;
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quick-tap-ms = <175>; // double tapping same key allows for repeating
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global-quick-tap-ms = <150>; // without PR #1387 use global-quick-tap instead
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bindings = <&kp>, <&kp>;
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hold-trigger-key-positions = <KEYS_R THUMBS>;
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hold-trigger-on-release; // requires PR #1423
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)
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/* right-hand HRMs */
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ZMK_BEHAVIOR(hmr, hold_tap,
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flavor = "balanced";
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tapping-term-ms = <280>;
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quick-tap-ms = <175>; // double tapping same key allows for repeating
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global-quick-tap-ms = <150>; // without PR #1387 use global-quick-tap instead
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bindings = <&kp>, <&kp>;
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hold-trigger-key-positions = <KEYS_L THUMBS>;
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hold-trigger-on-release; // requires PR #1423
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)
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```
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One last note, the configuration above uses some syntactic sugar introduced in [PR
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#1387](https://github.com/zmkfirmware/zmk/pull/1387), which decouples the
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`quick-tap-ms` timeout from the `global-quick-tap-ms` timeout. Without the PR, one
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can replace `global-quick-tap-ms = <150>` with `global-quick-tap` for a
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similar effect (`global-quick-tap` will use the regular `quick-tap-ms` timeout in this
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case).
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My personal [ZMK fork](https://github.com/urob/zmk) includes both the
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global-quick-tap-ms PR and the hold-trigger-on-release PR (along with a few other PRs).
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If you are looking for a ZMK-centric introduction to maintaining your own fork with a
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custom selection of PRs, you might find my ["cookbook
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approach"](https://gist.github.com/urob/68a1e206b2356a01b876ed02d3f542c7) helpful.
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## A few thoughts on the combo setup
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The combo layout is guided by two goals: (1) put all combos in easy-to-access locations,
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and (2) make them easy to remember. Specifically:
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- the top vertical-combo row matches the symbols on a standard numbers row
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(except `+` and `&` being swapped)
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- the bottom vertical-combo row aims for symmetry with the top row
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(subscript `_` aligns with superscript `^`; minus `-` aligns with `+`; division `/`
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aligns with multiplication `*`; logical-or `|` aligns with logical-and `&`)
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- parenthesis, braces, brackets, `!` and `?` all in prime access locations and set up
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symmetrically
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- a numlock shortcut (on `W + P`) for one-handed "data entry" (aka Sudoku 🙂)
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- shortcuts for cut (on `X + D`), copy, and paste on left side (good with right-handed
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mouse use)
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[^1]: I call it "timeless", because the large tapping-term makes the behavior
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insensitive to the precise timings. One may say that there is still the
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`global-quick-tap` timeout. However, with both a large tapping-term and
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positional-hold-taps, the behavior is *not* actually sensitive to the
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`global-quick-tap` timing: All it does is reduce the delay in typing; i.e., variations
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in typing speed won't affect *what* is being typed but merly *how fast* it appears on
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the screen.
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[^2]: One potential downside of `global-quick-tap` is that it prevents using modifiers
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*immediately* after another key press. Arguably, this is only problematic for shift,
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which is not a problem for me, because I have a dedicated "sticky shift" on my right
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thumb. If you rely on homerow mods for regular capitalization, you may want to reduce
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the `global-quick-tap` term for just the two shift-mods to about 75-100ms.
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