ZMK Configuration

A sophisticated ZMK (Zephyr Keyboard Firmware) configuration supporting both Mono and Split Corne keyboards with advanced features and custom behaviors.

Supported Keyboards

Mono Corne

• Controller: RP2040 Zero (e.g., Adafruit RP2040 Zero)
• Layout: 4x5+3 (36-key Corne layout with thumb cluster)
• Features: Faster tap timing for responsive feel

Split Corne

• Controllers:
  • Left/Right halves: nice!nano v2
  • Dongle: Raytac MDBT50Q-RX
• Layout: 6x5 split Corne layout with thumb clusters
• Features: Central dongle mode with enhanced Bluetooth capabilities

Key Features

Advanced Key Behaviors

• Hold-Tap Configurations: Multiple custom hold-tap behaviors optimized for different use cases
• Balanced Homerow Mods: Efficient modifier keys on home row using bhm behavior
• Smart Space/Backspace: Spacebar acts as backspace when held, shifted becomes Hyper key
• Adaptive Shift Keys: Shift becomes brackets when held
• Double-Tap Comma: Double-tap comma triggers caps word and deletes previous character

Layer System

1. Default Layer: QWERTY with homerow mods
2. Symbols Layer (1): Punctuation and symbols
3. Numbers Layer (2): Numeric pad layout
4. Arrows Layer (3): Arrow key navigation
5. Nav Layer (4): Advanced navigation with Hyper/Meh combos
6. Media Layer (5): Media controls
7. Bluetooth Layer (6): Device switching and management
8. Empty Layer: Available for custom configuration

Smart Combinations

• Space+Tab: Triggers caps word mode
• Caps Word: Automatic capitalization with smart continue list
• Layer Tap Fast: Quick layer access with optimized timing
• Hyper/Meh Keys: Advanced chorded key combinations

Project Structure

zmk-config/
├── config/
│   ├── base_36.keymap          # Main keymap with all layers
│   ├── mono_corne.keymap       # Mono-specific overrides
│   ├── corne.keymap           # Split-specific overrides
│   └── west.yml               # ZMK manifest with custom components
├── boards/
│   └── shields/
│       ├── mono_corne/        # Mono Corne board definitions
│       └── corne/             # Split Corne board definitions
├── build.yaml                 # GitHub Actions build matrix
└── README.md                  # This file

Setup Instructions

Prerequisites

• ZMK development environment set up
• West tool installed
• Compatible hardware (see Supported Keyboards section)

Building Firmware

Using GitHub Actions (Recommended)

1. Push changes to this repository
2. GitHub Actions will automatically build firmware for all supported configurations
3. Download the appropriate .uf2 file from the Actions tab

Local Build

# Update dependencies
west update

# Build for Mono Corne
west build -b rp2040_zero -- -DSHIELD=mono_corne

# Build for Split Corne (Left)
west build -b nice_nano_v2 -- -DSHIELD=corne_left -DCONFIG_ZMK_SPLIT=y -DCONFIG_ZMK_SPLIT_ROLE_CENTRAL=n

# Build for Split Corne (Right)
west build -b nice_nano_v2 -- -DSHIELD=corne_right -DCONFIG_ZMK_SPLIT=y -DCONFIG_ZMK_SPLIT_ROLE_CENTRAL=n

# Build for Corne Dongle
west build -b raytac_mdbt50q_rx -- -DSHIELD=corne_dongle

Flashing Firmware

RP2040 Zero (Mono Corne)

1. Connect RP2040 Zero while holding BOOTSEL button
2. Drag and drop the .uf2 file to the mounted drive

nice!nano v2 (Split Corne)

1. Use a programmer (like UF2 bootloader) or
2. Use OTA updates if already configured with ZMK

Raytac Dongle

1. Connect via USB while in bootloader mode
2. Flash the appropriate firmware file

Custom Components

This configuration uses several custom ZMK components:

• zmk-component-raytac-dongle: Enhanced dongle functionality
• zmk-component-rp2040-zero: RP2040 controller support
• zmk-adaptive-key: Adaptive key behaviors (e.g., double-tap comma)

Keymap Details

Home Row Modifiers

• A: Left Ctrl
• S: Left Alt
• D: Left Shift
• F: Left GUI
• J: Right GUI
• K: Right Shift
• L: Right Alt
• ;: Right Ctrl

Special Keys

• Space: Tap = Space, Hold = Backspace, Shift+Hold = Hyper
• Esc: Layer tap to Symbols layer
• Enter: Layer tap to Numbers layer
• Comma: Double-tap = Caps Word + Backspace

Layer Access

• Symbols: Esc (hold)
• Numbers: Enter (hold)
• Arrows: V (hold)
• Navigation: E (hold)
• Bluetooth: N (hold)
• Media: M (hold)

Bluetooth Configuration

The split configuration supports up to 5 Bluetooth profiles:

• Layer 6: Access Bluetooth switching controls
• BT_CLR: Clear all pairings
• BT_SEL 0-4: Switch between profiles
• Bootloader: Enter bootloader mode for flashing

Development Notes

Recent Optimizations

• Consolidated layer hold timing for better responsiveness
• Optimized tap timing differences between mono and split configurations
• Enhanced comma caps feature with adaptive behavior

Configuration Differences

• Mono Corne: 150ms tap timing for more responsive feel
• Split Corne: 200ms tap timing with additional safeguards for reliability

License

This configuration follows the ZMK project's MIT license. See individual component licenses for details.

Contributing

When making changes:

1. Test on both mono and split configurations if applicable
2. Update build.yaml if adding new board/shield combinations
3. Update this README if adding significant new features