qmk/qmk_firmware

[Bug][Split keyboard][RGB] When RGB wakes up from Sleep, only Master RGB wakes up until a key on the Slave half is pressed

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#25,584 opened on Aug 28, 2025

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bughelp wanted

Description

Describe the Bug

Hi all

  • I'm using a Boardsource Unicorne (so split keyboard)
  • In my config.h I have these two commands
  • #define RGB_MATRIX_TIMEOUT 60000
  • #define SPLIT_RGB_MATRIX_ENABLE
  • The RGB sleep/ timeout works as expected, on both halves
  • (I even get the caps word change in RGB to reflect on both sides , so I know the two halves are in sync)
  • However, when RGB sleep is active and I press a key on the Master half (which is the left side for me), the Master RGB wakes up , but the right / Slave RGB does not wake up. Until I press a key on the Slave half
  • How can I fix this? Is there anything wrong with my setup?
  • My files can be found here - https://github.com/kmsingh-git/qmk_firmware/tree/master/keyboards/boardsource/unicorne . The keymap is under keymaps/mvrck_keymap_unicorne_6x3 if that's relevant

Keyboard Used

boardsource/unicorne

Link to product page (if applicable)

No response

Operating System

No response

qmk doctor Output

Is AutoHotKey / Karabiner installed

  • AutoHotKey (Windows)
  • Karabiner (macOS)

Other keyboard-related software installed

No response

Additional Context

No response

Contributor guide

Tech stack
c
Domain
None
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
QMK basicsSplit keyboard conceptsRGB matrix configuration
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Investigate the RGB matrix sync mechanism in split keyboards. Look at the QMK firmware code for split RGB matrix initialization, specifically how the slave half is notified to wake up. Check the files related to split keyboard functionality in the QMK core (e.g., quantum/split common/split util.c or rgb matrix.c). Consider whether the RGB MATRIX TIMEOUT and SPLIT RGB MATRIX ENABLE configurations are correct. Review the user's keymap at the provided GitHub link for any customizations.
[Bug][Split keyboard][RGB] When RGB wakes up from Sleep, only Master RGB wakes up until a key on the Slave half is pressed · qmk/qmk_firmware#25584 | Good First Issue