Corne 4.1 QMK Firmware (6-Column Colemak)

This repository contains the QMK configuration for my Corne (CRKBD) 4.1 split keyboard, running custom firmware built using QMK. The layout is based on Colemak, inspired by the principles of Miryoku — minimal finger travel, home-row mods, and layered functionality. The outer columns are disabled for a cleaner 5-column effective layout.

Hardware

• Keyboard: Corne 4.1 (6-column with outer columns disabled)
• Firmware: QMK Firmware
• Layout Style: Colemak, Miryoku-inspired
• MCU: RP2040 (Raspberry Pi Pico)
• Connection: USB-C wired

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Features

• ✅ Home row modifiers with per-key optimized timing
• 🎯 Tap dance for bracket pairs: (), [], {}
• 🔢 Five dedicated layers: Base, Numpad, Navigation, Media, Function
• 🖥️ OLED displays with WPM counter and bongo cat animation
• 🎛️ Encoder support for volume/media control
• 🧠 Ergonomic thumb cluster layer access

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Layer Overview

🅱 Base Layer (Colemak)

• Home-row mods: A=Ctrl, R=Alt, S=Cmd, T=Shift | N=Shift, E=Cmd, I=Alt, O=Ctrl
• Thumb cluster: NAV/Tab, Backspace, NUMPAD/Enter, Space, FUNCTION/Quote, MEDIA/Grave

🔢 Numpad Layer

• Left: Traditional numpad with operators (*, /, +, -, =)
• Right: Symbols and tap dance brackets
  • TD(BRKT1): ( / )
  • TD(BRKT2): [ / ]
  • TD(BRKT3): { / }

🧭 Navigation | 🔧 Function | 🎵 Media

• NAV: Arrow keys + Escape
• FUNCTION: F1-F12 + tap dance controls
• MEDIA: Volume and playback controls

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Custom Behaviors

🏠 Home Row Modifiers

// Optimized per-key tapping terms
HOME_A/O (Ctrl): TAPPING_TERM + 40ms
HOME_R/I (Alt):  TAPPING_TERM + 30ms  
HOME_S/E (Cmd):  TAPPING_TERM - 10ms
HOME_T/N (Shift): TAPPING_TERM - 20ms

🎯 Tap Dance Brackets

[BRKT1] = ACTION_TAP_DANCE_DOUBLE(LSFT(KC_9), LSFT(KC_0)),    // ( )
[BRKT2] = ACTION_TAP_DANCE_DOUBLE((KC_LBRC), (KC_RBRC)),      // [ ]
[BRKT3] = ACTION_TAP_DANCE_DOUBLE(LSFT(KC_LBRC), LSFT(KC_RBRC)), // { }

🖥️ OLED Features

• Master (Left): WPM Counter + Bongo Cat Animation
  • Idle (0-10 WPM): Cat sits peacefully, slowly breathing
  • Prep (10-30 WPM): Cat gets ready, paws positioned over drums
  • Active (30+ WPM): Cat energetically plays the bongos!

Bongo cat responds to your typing speed - the faster you type, the faster he drums!

• Slave (Right): Current layer indicator (BASE, NUM, NAV, MEDIA, FUN)

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Building and Configuration

Build Commands

# Build and flash
qmk compile -kb crkbd/rev1 -km your_keymap_name
qmk flash -kb crkbd/rev1 -km your_keymap_name

Key Features Enabled

// rules.mk
OLED_ENABLE = yes          # OLED displays
WPM_ENABLE = yes           # WPM calculation  
TAP_DANCE_ENABLE = yes     # Tap dance functionality
ENCODER_ENABLE = yes       # Rotary encoder support
SPLIT_KEYBOARD = yes       # Split keyboard support

Recommended Settings

// config.h
#define TAPPING_TERM 200              # Base tapping term
#define PERMISSIVE_HOLD              # Aggressive mod-tap
#define IGNORE_MOD_TAP_INTERRUPT     # Prevent accidental triggers

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Customization

Add New Layer

enum layers { _BASE, _NUMPAD, _NAV, _MEDIA, _FUNCTION, _CUSTOM };

[_CUSTOM] = LAYOUT_split_3x6_3(
    XXXXXXX, _______, _______, _______, _______, _______,    _______, _______, _______, _______, _______, XXXXXXX,
    // ... your layout
),

Adjust Timing

// In get_tapping_term()
case HOME_A: return TAPPING_TERM + 50;  // Slower/faster

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Troubleshooting

Split sync issues: Check TRRS cable
OLED not working: Verify OLED_ENABLE = yes
Accidental mod triggers: Adjust tapping terms
USB-C detection: Try different cable/port

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Keymap Visualization

Generate diagrams using keymap-drawer:

keymap parse -c 10 -z keymap.c > keymap.yaml
keymap draw keymap.yaml > keymap.svg

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License

MIT License – see LICENSE.
Built on the excellent work of the QMK and Miryoku communities.

Credits

• QMK Firmware: QMK Contributors
• Miryoku Layout: Manna Harbour
• Corne Keyboard: foostan

Author

Custom layout and configuration by [undergroundpost].