Corne (CRKBD)

Overview

The Corne (CRKBD) is the primary keyboard for both ratataque and GrimalDev. It's a 42-key split columnar stagger board running ZMK firmware. The minimal key count forces efficient use of layers.

Why Corne?

• 42 keys forces intentional layer design
• Columnar stagger reduces finger travel
• Split allows natural shoulder width
• Thumb clusters replace pinky-heavy modifiers
• Portable -- easy to carry between setups

GrimalDev's Layout

QWERTY base with custom hold-tap behaviors and French unicode support.

Hold-Tap Behaviors

// Positional hold-tap for left/right ctrl
/ {
    behaviors {
        left_ctrl: left_ctrl {
            compatible = "zmk,behavior-hold-tap";
            #binding-cells = <2>;
            flavor = "balanced";
            tapping-term-ms = <280>;
            quick-tap-ms = <175>;
            hold-trigger-key-positions = <6 7 8 9 10 11 18 19 20 21 22 23 30 31 32 33 34 35 39 40 41>;
            bindings = <&kp>, <&kp>;
        };
        right_ctrl: right_ctrl {
            compatible = "zmk,behavior-hold-tap";
            #binding-cells = <2>;
            flavor = "balanced";
            tapping-term-ms = <280>;
            quick-tap-ms = <175>;
            hold-trigger-key-positions = <0 1 2 3 4 5 12 13 14 15 16 17 24 25 26 27 28 29 36 37 38>;
            bindings = <&kp>, <&kp>;
        };
    };
};

Layers

┌─────────────────────────────────────────────────────────────────┐
│ QWERTY (Base)                                                    │
│ TAB  Q  W  E  R  T  │  Y  U  I  O  P  BSPC                    │
│ ESC  A  S  D  F  G  │  H  J  K  L  ;  '                        │
│ SHFT Z  X  C  V  B  │  N  M  ,  .  /  SHFT                    │
│           GUI ALT L1 │ SPC L2 CTRL                              │
├─────────────────────────────────────────────────────────────────┤
│ Layer 1: Numbers & Symbols                                       │
│  `   1  2  3  4  5  │  6  7  8  9  0  DEL                      │
│  ~   !  @  #  $  %  │  ^  &  *  (  )  |                        │
│ SHFT _  +  {  }  \  │  -  =  [  ]  /  SHFT                    │
│           GUI ALT __ │ SPC __  CTRL                              │
├─────────────────────────────────────────────────────────────────┤
│ Layer 2: System / Media / BT                                     │
│  F1  F2  F3  F4  F5  F6 │ F7  F8  F9  F10 F11 F12             │
│ BT0 BT1 BT2 BT3 BT4 __ │ LFT DWN UP  RGT __  __              │
│ BTCLR __ __ __ __ __     │ MUTE VOLD VOLU PREV NEXT PLAY       │
│              GUI ALT __  │ SPC __  CTRL                          │
└─────────────────────────────────────────────────────────────────┘

Combos

// ctrl+h for backspace
combo_bspc {
    timeout-ms = <50>;
    key-positions = <16 19>;  // F + H
    bindings = <&kp BSPC>;
};
 
// ctrl+m for enter
combo_enter {
    timeout-ms = <50>;
    key-positions = <16 31>;  // F + M
    bindings = <&kp RET>;
};

French Unicode

French characters are supported via ZMK includes for accented characters (é, è, ê, à, ù, ç).

Hardware

• E-ink display enabled nice!view
• Battery proxy for split monitoring

ratataque's Layout

Three layers: QWERTY base, symbols, and navigation. The firmware also includes a Colemak layer for experimentation.

Key features:

• Home row mods (disabled currently in favor of dedicated modifier keys)
• Symbol layer on left thumb hold
• Nav layer on right thumb hold
• Numbers on the top row of nav layer
• French accent layer (é, è, ê, à, ù, ç)

Firmware

Both contributors use ZMK firmware built via GitHub Actions. Push to the zmk-config repo triggers a build that produces a .uf2 file ready to flash.

# ZMK build matrix (west.yml)
include:
  - board: nice_nano_v2
    shield: corne_left
  - board: nice_nano_v2
    shield: corne_right

Build

The physical keyboard uses:

• MCU: nice!nano v2 (nRF52840)
• Switches: epomaker blue bird linear switches (low actuation point and force)
• Keycaps: MDA profile PBT
• Case: 3D printed or FR4 plate