Summary
On the Halcyon Corne rev2,
the Encoder module
(the encoder-rev2 knob press, KC_MUTE by default) only works while its own half is the USB master.
When the other half is plugged into USB, the button press is dropped.
Environment
- Keyboard: Splitkb Halcyon Corne rev2 (split)
- Firmware: stock release
latest-halcyon-qmk (2026-08-26), the "no Vial" builds
- Encoder rev2 module (with button) physically on the left half
- Cirque trackpad module selected for the right half build.
Reproduction
- Flash
..._default_hlc_encoder_rev2.uf2 to the left half and
..._default_hlc_cirque_trackpad.uf2 to the right half.
- Plug the right half into USB (right = master).
Press the left knob's push button.
No operation happens.
- Plug the left half into USB (left = master).
Press the same left knob's push button.
Mute toggle as expected.
In step 2, with the right half as master, the following all still work from the
left half:
- knob rotation (volume change)
- all normal keys
Rotation, keys and pointer all work from the slave half — only the module
push button drops.
Summary
On the Halcyon Corne rev2,
the Encoder module
(the encoder-rev2 knob press,
KC_MUTEby default) only works while its own half is the USB master.When the other half is plugged into USB, the button press is dropped.
Environment
latest-halcyon-qmk(2026-08-26), the "no Vial" buildssplitkb_halcyon_corne_rev2_default_hlc_encoder_rev2.uf2splitkb_halcyon_corne_rev2_default_hlc_cirque_trackpad.uf2Reproduction
..._default_hlc_encoder_rev2.uf2to the left half and..._default_hlc_cirque_trackpad.uf2to the right half.Press the left knob's push button.
No operation happens.
Press the same left knob's push button.
Mute toggle as expected.
In step 2, with the right half as master, the following all still work from the
left half:
Rotation, keys and pointer all work from the slave half — only the module
push button drops.