Ferris Sweep Configuration Files

Ferris Sweep has a simpler configuration layout than Sweep Pro. Most user-facing changes live in config/cradio.keymap and config/cradio.conf.

Use ZMK Studio for live keymap edits when possible. Use this page when the setting needs a source-file change and a new firmware build.

File Map

File	What it controls	Usually flash
`config/cradio.keymap`	Layers, key bindings, home-row modifiers, conditional tri-layer, mouse layer, soft-off wake behavior, battery report behavior wiring, pointer movement keys, and scroll keys.	Usually left/main half; flash right too if you changed split or right-side behavior.
`config/cradio.conf`	Bluetooth, USB, battery reporting, idle/sleep behavior, pointing support, ZMK Studio, behavior queue size, and keyboard name.	Both halves that use this shared config.
`config/behaviors/character_map.dtsi`	Character map used by text/report style behaviors.	Left/main half if changed.
`config/behaviors/report.dtsi`	Battery/report behavior used by the keymap.	Left/main half if changed.
`config/behaviors/send_string.dtsi`	Helper macro for defining send-string behaviors.	Left/main half if changed and used by your keymap.
`build.yaml`	GitHub Actions build matrix for `cradio_left`, `cradio_right`, and `settings_reset`.	No direct flashing; it controls which UF2 files Actions builds.

Common Detailed Adjustments

Goal	Change here	Notes
Change keys or layers	`config/cradio.keymap`	Re-render the Ferris Sweep keymap diagrams after changing public defaults.
Change home-row modifier timing	`ht` behavior in `config/cradio.keymap`	Current timing is `tapping-term-ms = <200>` and `quick-tap-ms = <150>`.
Change the tri-layer rule	`conditional_layers` in `config/cradio.keymap`	The current function layer turns on when both right and left layers are active.
Change mouse layer keys	`mouse` layer in `config/cradio.keymap`	This controls `MB4`, `MB5`, `MCLK`, movement keys, and scroll keys.
Tune key-based pointer movement or scrolling	`mmv` and `msc` in `config/cradio.keymap`	These are firmware behavior settings for movement and scroll keys, not an OS setting.
Change Bluetooth slots or pairing capacity	`CONFIG_BT_MAX_CONN` and `CONFIG_BT_MAX_PAIRED` in `config/cradio.conf`	Current value is 5.
Change battery reporting	`CONFIG_ZMK_BATTERY_REPORTING*` and `CONFIG_ZMK_BATTERY_REPORT_INTERVAL` in `config/cradio.conf`	Current interval is 180 seconds.
Change sleep behavior	`CONFIG_ZMK_IDLE_TIMEOUT`, `CONFIG_ZMK_SLEEP`, and `CONFIG_ZMK_IDLE_SLEEP_TIMEOUT` in `config/cradio.conf`	Current sleep timeout is one hour.
Change keyboard Bluetooth name	`CONFIG_ZMK_KEYBOARD_NAME` in `config/cradio.conf`	Keep it 16 characters or shorter.
Change build artifacts	`build.yaml`	The default Actions matrix builds `cradio_left`, `cradio_right`, and `settings_reset`.

Build Targets

Ferris Sweep uses one left firmware and one right firmware:

Firmware	Shield	Use
`cradio_left`	`cradio_left`	Main left half, with ZMK Studio USB RPC in the default build matrix.
`cradio_right`	`cradio_right`	Right half.
`settings_reset`	`settings_reset`	Clears Bluetooth pairing and stored ZMK settings.

The default build.yaml matrix is:

include:
  - board: nice_nano//zmk
    shield: cradio_left
    snippet: studio-rpc-usb-uart
  - board: nice_nano//zmk
    shield: cradio_right
  - board: nice_nano//zmk
    shield: settings_reset

Rebuild Guidance

If you changed only live keymap content through ZMK Studio, you usually do not need to rebuild firmware.
If you changed config/cradio.keymap, rebuild the left/main firmware at minimum.
If you changed shared options in config/cradio.conf, rebuild both halves.
If you changed build.yaml, run the GitHub Actions build again and download the newly generated UF2 artifacts.

See Build your own firmware for the exact GitHub Actions and local build commands.