SABLUTE LD-135 Linux Backlight

Set a SABLUTE LD-135 keyboard to steady white when you sign in to Linux. The helper preserves brightness and speed, runs once, and exits. You can still use Fn + 2 to change colors afterward.

Project website · Protocol notes · Contributing

What has been tested

The command and login setup were verified on one SABLUTE LD-135 revision with Ubuntu 24.04 on x86_64. Changing another solid color to white, preserving the other lighting fields, skipping an already-white keyboard, and using Fn + 2 afterward all worked. White at graphical login was confirmed after a reboot.

White is applied after you sign in. The keyboard may show its factory color during boot or at the login screen. Complete power disconnection, suspend/resume, and unplug/replug behavior have not been verified. The helper does not run again on resume or reconnect; you can run ld135-white manually when needed.

Device requirement	Verified value
Label	SABLUTE LD-135
USB vendor/product ID	30fa:2052
USB name	INSTANT USB Keyboard
HID interface	USB interface 01, vendor feature report 07
Feature report size	8 bytes, including the report ID

The helper also requires this exact HID report descriptor SHA-256:

fc4de9961c5a701ba6f2aa806c0d85a6478104e1864fef2d0020cf5c7c093c48

A matching product name or USB ID alone is insufficient. Other revisions and related Instant keyboards are not supported automatically. Multiple matching keyboards cause the helper to stop without changing either one.

Install

Requirements: Linux with hidraw, Python 3, udev, and a graphical desktop that supports XDG autostart and active-session device access. The verified environment is Ubuntu 24.04 x86_64 with Python 3.12. The Python programs use only the standard library; no pip packages or Windows software are needed.

Download the source or clone the repository, then enter its directory:

git clone https://github.com/bell-kevin/sablute-ld135-linux-backlight.git
cd sablute-ld135-linux-backlight

Identify the supported interface without opening it:

python3 keyboard_white.py --dry-run

Install the system helper and its device-access rule:

sudo python3 install_keyboard_white.py --system install

As your regular desktop user, test the command and enable login startup:

ld135-white --status
ld135-white
python3 install_keyboard_white.py --autostart enable

Run the autostart command without sudo: it belongs to the user who wants white at login. Each desktop user can enable it separately. The installer grants the active local desktop user access to the matching vendor interface; it does not grant everyone access to all keyboards.

The login entry runs ld135-white --wait 30, allowing up to 30 seconds for the keyboard and its access permissions to become available. Administrator access is needed for system installation, not for normal lighting changes.

Use

ld135-white              # Set steady white once
ld135-white --status     # Read the current lighting status
ld135-white --dry-run    # Identify the interface without opening it
ld135-white --wait 30    # Wait for the device, then set white once

To check the change yourself, use Fn + 2 to select another color, run ld135-white, and check that it becomes white. Fn + 2 continues working after the program exits. There is no background service enforcing a color.

The helper reads the current brightness/speed byte and preserves it. It sends at most one runtime lighting command per invocation, verifies the result, and sends no EEPROM or firmware programming commands. If it is already steady white, no lighting write is sent. The program does not read keystroke events or use the network. See PROTOCOL.md for the verified packet and its limits.

Disable, upgrade, or uninstall

Disable automatic white at login while keeping the manual command:

python3 install_keyboard_white.py --autostart disable

To upgrade, obtain the new source, run the system installer again, and refresh your login entry:

sudo python3 install_keyboard_white.py --system install
python3 install_keyboard_white.py --autostart enable

To remove the login entry and system files:

python3 install_keyboard_white.py --autostart disable
sudo python3 install_keyboard_white.py --system uninstall

For shared computers, each user who enabled autostart should disable their own entry. Uninstalling does not change the keyboard's currently selected color. The installer supports --dry-run to preview an install, removal, or autostart change without applying it.

Installed path	Purpose
/usr/local/lib/ld135-white/keyboard_white.py	Lighting helper
/usr/local/bin/ld135-white	Command launcher
/etc/udev/rules.d/70-ld135-white.rules	Access to the matching vendor interface
~/.config/autostart/ld135-white.desktop	Per-user graphical-login entry; uses an absolute XDG_CONFIG_HOME when set

Troubleshooting

No matching interface: check lsusb -d 30fa:2052 and run python3 keyboard_white.py --dry-run from the source directory. An ID match with a descriptor mismatch is deliberately rejected; please report the revision instead of removing the identity checks.

Access denied: run the system installer from the active graphical session, then try ld135-white --wait 30. A remote or text-only login may not receive the active-desktop access granted by uaccess.

Manual command works, login startup does not: run the regular-user --autostart enable command again and check that your desktop supports XDG autostart. This project does not install a boot service.

Fn is held or the state keeps changing: release Fn and try again. The helper waits briefly for a stable status before writing. A failed write or verification is reported without repeating the command.

For a read-only report from the source checkout, use:

python3 keyboard_white.py --dry-run
python3 keyboard_white.py --status

Open an issue with your device label, USB ID, distribution, architecture, desktop, command output, and whether manual Fn controls still work. Remove personal paths or other unrelated information from logs.

Development and related work

Run the automated tests without a keyboard or administrator privileges:

python3 -m unittest discover -v

The core controller tests cover identity checks, single-write behavior, brightness preservation, verification failures, and waiting for Fn to be released. Hardware verification and platform coverage are described above; automated tests alone do not establish support for another keyboard.

Related Instant-controller research includes Adventurer K812 / IST83025B, Instant K201 Linux configuration, and OpenRGB's Thor 210 investigation. PROTOCOL.md records the manufacturer's utility sources and the local observations behind this implementation.

License

GNU Affero General Public License, version 3. See LICENSE.

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