A wireless, per‑key‑RGB, OLED‑equipped split keyboard powered by nice!nano v2 (compatible)

This repository contains the complete ZMK firmware configuration for my custom Corne V3 split keyboard:

• MCUs: 2× nice!nano v2 (nRF52840, BLE 5.0, Li‑Po charging)
• Switch matrix: 3×6 + 3 (per half)
• Lighting: 42 × WS2812 per‑key LEDs + 12 × underglow (GRB)
• Display: 0.91 “ 128×32 SSD1306 OLED on each half
• Power: 302 mAh Li‑Po, magnetic charging pogo‑pins
• Host OS: macOS 15, but any BLE‑enabled OS works

The firmware is built with ZMK $Zephyr Mechanical Keyboard$ and provides:

• True wireless split (BLE link between halves, no TRRS needed)
• Up to 5 easily switchable host profiles
• Layer & output status on the OLED
• Comprehensive RGB underglow / per‑key effects (breathe, cycle, reactive)
• VIA‑style live keymap editing with ZMK Studio

https://zmk.dev/docs/user-setup

# Build central (left)
west build -p -b nice_nano_v2 -d build/left  -- -DSHIELD="corne_left nice_view_adapter nice_view" -DSNIPPET="studio-rpc-usb-uart" -DCONFIG_ZMK_STUDIO=y
# Build peripheral (right)
west build -p -b nice_nano_v2 -d build/right -- -DSHIELD="corne_right nice_view_adapter nice_view"

1. Double‑tap RESET on the MCU → it mounts as NICENANO.
2. Copy build/zephyr/zmk.uf2 onto the drive.
3. Repeat for the other half.

• Pairing mode: Ctrl + Shift + J (hold >3 s) — host sees “ZMK‑Corne”.
• Cycle profiles: Ctrl + Shift + K.
• Erase profiles: Ctrl + Shift + P (long‑hold).
• Peripheral ↔ central link is automatic after power‑on (blue LED solid).

Keybindings (Layer FN):

RGB_TOG  RGB_HUI  RGB_SAI  RGB_BRI  RGB_EFF

• Default effect: Breathe
• Underglow & per‑key share the same effect engine but can be toggled independently in prj.conf.

Widgets blank after 15 s of idle to save ~15 mA.

Detailed .keymap lives in /config/corne.keymap and is editable via Keymap Editor or ZMK Studio.

• Average typing current: 7 mA with OLED off, RGB off. → ~40 h on a 302 mAh cell.
• Enable CONFIG_ZMK_RGB_SLEEP & CONFIG_ZMK_DISPLAY_BLANK_ON_IDLE (already set) for multi‑week standby.
• Charging LED on nice!nano v2 turns green at ~4.2 V.

• Add encoders: see /docs/encoders.md for GPIO mapping.
• Dongle mode: flash a third nRF board with central_dongle target and leave it in a USB port for faster resume.
• QMK port: experimental RP2040 branch lives in feature/qmk‑rp2040 — still WIP.

• ZMK Docs
• Keymap Editor
• ZMK Studio

Made with ☕ by @lysandroc