Corne Keyboard Custom Keymaps (ZMK)

Custom keymaps for a Corne 42-key split keyboard running ZMK firmware.

Table of Contents

• Hardware Info
• Current Keymap
• Related Resources
• Pre-requisites
• Clone Repository
• Editing the Keymap
• Building Firmware
• Flashing the Keyboard
  • 1. Download the firmware
  • 2. Connect the keyboard half via USB
  • 3. Enter bootloader mode
  • 4. Flash the firmware
  • 5. Repeat for the other half
  • 6. Re-pair Bluetooth
• Settings Reset
  • When to reset
  • How to reset
• Issues
  • Bluetooth pairing issues
  • Layers not switching correctly
  • Keyboard name not changing after flash
• RGB Underglow
• Enabling ZMK Studio

Hardware Info

Property	Value
Keyboard	Corne (crkbd) 6-column split
Keys	42 (3x6 + 3 thumbs per side)
MCU	nRF52840 (nice!nano v2 compatible)
Firmware	ZMK
Connection	Bluetooth Low Energy (BLE)
Device Name	Afiq Zudin Corne42
Display	SSD1306 OLED 128x32 (nice_oled module)
LEDs	WS2812 underglow (6/half) + per-key (21/half) — 54 total
BT Profiles	5 (BT0-BT4)
ZMK Studio	Disabled (see Enabling ZMK Studio)
Vendor	KeebMaker
Vendor Config	KeebMaker/zmk-config

Current Keymap

See keymap-drawer/ for text reference and keymap-drawer source files.

Related Resources

• ZMK Firmware Documentation
• ZMK Keycodes Reference
• ZMK Studio - Live keymap editor (no flashing needed)
• Keymap Editor - Visual keymap editor for GitHub repos
• Vendor Config (KeebMaker)

Pre-requisites

• Corne Keyboard (KeebMaker variant)
• macOS
• USB-C cable
• GitHub account (for building firmware via Actions)
• This Repository - Custom Corne Keymaps

Clone Repository

git clone git@github.com:afiqzudinhadi/zmk-config.git

Editing the Keymap

Edit Config Files

For full customization (combos, steno layer, behaviors):

config/
├── corne.keymap          <- Edit this for keymap changes
├── corne.conf            <- Edit this for feature toggles (RGB, display, BLE)
└── west.yml              <- ZMK module dependencies (usually no changes needed)

Keymap guide can be found here.

Building Firmware

1. Push changes to GitHub
2. Go to Actions tab → latest workflow run
3. Wait for the build to complete (green checkmark)
4. Download the firmware artifact (zip file)
5. Extract — contains .uf2 files for left and right halves

If Actions is disabled on your fork: go to Actions tab → click "I understand my workflows, go ahead and enable them".

Flashing the Keyboard

1. Download the firmware

Download the firmware.zip from the GitHub Actions artifacts and extract it.

The zip contains:

• nice_corne_left_oled_rgb-nice_nano_v2-zmk.uf2 — left half
• nice_corne_right_oled_rgb-nice_nano_v2-zmk.uf2 — right half
• nice_settings_reset-nice_nano_v2-zmk.uf2 — settings reset (see Settings Reset)

2. Connect the keyboard half via USB

Plug in the left half of the keyboard with a USB-C cable.

3. Enter bootloader mode

Double-tap the reset button on the keyboard. The keyboard will appear as a USB drive (e.g. NICENANO).

• The reset button is on the PCB (check underneath the keyboard or through the case hole).
• The LEDs on the keyboard will turn off.
• If the drive doesn't appear, try double-tapping faster or slower.

4. Flash the firmware

Drag the left .uf2 file onto the USB drive. The keyboard will automatically reboot and the drive will disappear.

5. Repeat for the other half

1. Plug in the right half via USB-C
2. Double-tap the reset button
3. Drag the right .uf2 file onto the USB drive

6. Re-pair Bluetooth

If you changed the keyboard name or did a settings reset:

1. Open System Settings → Bluetooth on macOS
2. Remove the old keyboard entry (e.g. Corne_Oled_RGB)
3. Put the keyboard in pairing mode (it should be discoverable automatically)
4. Pair with Afiq Zudin Corne42

Settings Reset

When to reset

Do a settings reset when:

• Layer structure changed (layers added, removed, or reordered) — ZMK Studio saved state stores the old layer layout and will override the new compiled keymap
• Layers are not switching correctly after flashing new firmware
• Keyboard name didn't change after flash
• Both halves won't pair with each other
• ZMK Studio saved changes are interfering with your compiled keymap
• Bluetooth pairing issues after firmware update

How to reset

1. Download nice_settings_reset-nice_nano_v2-zmk.uf2 from the firmware artifacts
2. Connect the left half via USB
3. Double-tap the reset button to enter bootloader mode
4. Drag nice_settings_reset-nice_nano_v2-zmk.uf2 onto the USB drive
5. Immediately double-tap reset again to put it back in bootloader mode (to avoid accidental bonding)
6. Repeat steps 2-5 for the right half
7. Now flash the actual firmware to both halves (left .uf2 to left, right .uf2 to right)
8. After flashing both halves, reset both at the same time to pair them together
9. Remove old Bluetooth entry from macOS and re-pair

Issues

Bluetooth pairing issues

If the keyboard won't pair after flashing:

1. Clear the BT profile: go to HUB layer → press BT_CLR
2. Remove the device from macOS Bluetooth settings
3. Re-pair

If issues persist, do a full Settings Reset.

Layers not switching correctly

If ->STEN, ->FPS, or other layer switches go to CARP instead of the expected layer, ZMK Studio's saved state is overriding your compiled keymap. Do a Settings Reset to clear it.

Keyboard name not changing after flash

The BLE name is cached in device settings. Do a Settings Reset and re-pair.

RGB Underglow

Hardware

54 WS2812 LEDs total — 6 underglow + 21 per-key per half. Chain length set in config/nice_nano_v2.overlay.

Config

RGB settings are in config/corne.conf:

Setting	Value	Description
CONFIG_ZMK_RGB_UNDERGLOW	y	Enable RGB
CONFIG_ZMK_RGB_UNDERGLOW_ON_START	n	Off on boot
CONFIG_WS2812_STRIP	y	WS2812 LED driver
CONFIG_ZMK_RGB_UNDERGLOW_EFF_START	3	Default effect: 0=Solid, 1=Breathe, 2=Spectrum, 3=Swirl
CONFIG_ZMK_RGB_UNDERGLOW_BRT_STEP	1	Brightness step (%)
CONFIG_ZMK_RGB_UNDERGLOW_AUTO_OFF_IDLE	y	Turn off when idle
CONFIG_ZMK_RGB_UNDERGLOW_EXT_POWER	n	Don't toggle external power with RGB

Optional tuning (commented out in config):

• HUE_STEP / SAT_STEP — hue and saturation adjustment step
• HUE_START / SAT_START / BRT_START — initial color values

Effects

EFF_START	Effect
0	Solid color
1	Breathe
2	Spectrum
3	Swirl

Cycle at runtime with RGB_EFF (next) / RGB_EFR (previous).

Keycodes

Keycode	Action
RGB_TOG	Toggle on/off
RGB_EFF	Next effect
RGB_EFR	Previous effect
RGB_HUI / RGB_HUD	Hue up/down
RGB_SAI / RGB_SAD	Saturation up/down
RGB_BRI / RGB_BRD	Brightness up/down
RGB_SPI / RGB_SPD	Speed up/down
RGB_COLOR_HSB(h,s,b)	Set specific color

Docs: zmk.dev/docs/keymaps/behaviors/underglow · zmk.dev/docs/config/underglow

Runtime Controls (HUB Layer)

Key	Action
[RGB]	Tap-dance: 1×=toggle, 2×=effect fwd, 3×=effect rev
[CLR]	Tap-dance color presets: purple → white → red → blue → green
HUE+ / HUE-	Adjust hue
SAT+ / SAT-	Adjust saturation
BRT+ / BRT-	Adjust brightness

Enabling ZMK Studio

ZMK Studio is disabled by default in this config. To enable live keymap editing:

1. In config/corne.conf, uncomment:

   CONFIG_ZMK_STUDIO=y
   CONFIG_ZMK_STUDIO_LOCKING=n
   

2. In build.yaml, add studio-rpc-usb-uart to the left half snippet:

   snippet: rgb-config studio-rpc-usb-uart
   

3. Push and flash.

4. Go to zmk.studio in Chrome → connect via USB or BLE → edit layers visually.

Limitations: Cannot add combos, custom behaviors, or change display/RGB config.

Warning: ZMK Studio saves changes to flash storage. These override the compiled keymap. If layers behave unexpectedly after flashing, do a Settings Reset.

Per-Key RGB Layer Indicators

Uses darknao's per-key RGB patches cherry-picked onto ZMK v0.3.0 at afiqzudinhadi/zmk@rgb-layer.

Effect #4 (Layer Indicators) shows different per-key colors based on active keymap layer. Colors are defined as hex RGB values in corne.keymap under the underglow-layer node.

LED Chain Order (Foostan Corne v1.1)

Column-by-column snake, not row-by-row:

Chain 0-5:   Underglow (6 LEDs)
Chain 6-9:   Thumb outer → bottom/home/top col0
Chain 10-12: Top/home/bottom col1
Chain 13-14: Thumb mid → Thumb inner
Chain 15-17: Bottom/home/top col2
Chain 18-20: Top/home/bottom col3
Chain 21-23: Bottom/home/top col4
Chain 24-26: Top/home/bottom col5

Changing Layer Colors

Edit underglow-layer bindings in config/corne.keymap. Each layer has 42 entries (one per key position):

carp_rgb {
    layer-id = <0>;
    bindings = <&ug GREEN &ug BLUE ...>;  // 42 entries
};

Available colors (dt-bindings/zmk/rgb_colors.h): GREEN RED BLUE TEAL ORANGE YELLOW GOLD PURPLE PINK WHITE ___ (off)

Custom colors: #define CYAN 0x00ffff then &ug CYAN

Notes

• chain-length = <27> must be set in corne.keymap — the fork's shield overlay defaults to 10.
• Underglow LEDs turn off on effect #4 (mapped to 255 in pixel-lookup). To give them layer colors, map to key positions instead of 255.
• Brightness/hue/saturation controls don't affect layer indicator colors (#1, #4).
• Custom RGB effects can be added in the ZMK fork (app/src/rgb_underglow.c).