A tiny Python daemon that turns a cheap Jieli‑based USB volume knob into a fully integrated KDE media controller. It reads the device’s raw USB HID packets, interprets rotation + button presses, and triggers KDE’s native media shortcuts.

This gives you:

• KDE’s volume popup when turning the knob

• Smooth, adjustable volume control

• Play/pause on Dial Press

• Next/previous track support

• Zero CPU usage when idle

• Automatic recovery if the kernel steals the HID interface

• Autostart support (KDE or systemd user service)

This script behaves like a custom driver, without touching the kernel.

This script is built for the common Jieli‑based USB volume knobs sold under many names.

USB IDs:

• Vendor: 0x4c4a

• Product: 0x4155

If your knob reports those IDs, this script will work.

Install these system packages:

bash

sudo apt install python3 python3-usb xdotool playerctl

• python3-usb — talks directly to the USB HID interface

• xdotool — sends KDE’s volume + play/pause key events

• playerctl — handles next/previous track reliably via MPRIS

To allow the script to access the knob without sudo, create:

Code

/etc/udev/rules.d/99-jieli-knob.rules

With:

Code

SUBSYSTEM=="usb", ATTR{idVendor}=="4c4a", ATTR{idProduct}=="4155", MODE="0666"

Reload rules:

bash

sudo udevadm control --reload-rules
sudo udevadm trigger

Unplug/replug the knob.

Place the script anywhere (recommended: ~/.local/bin/Knobbie.py) and run:

bash

python3 ~/.local/bin/Knobbie.py

You should see:

Code

KDE Volume Knob Daemon Running...

Turn the knob — KDE’s volume popup should appear.

Create:

Code

~/.config/autostart/knobbie.desktop

Contents:

ini

[Desktop Entry]
Type=Application
Exec=python3 /home/eric/.local/bin/Knobbie.py
Hidden=false
NoDisplay=false
X-GNOME-Autostart-enabled=true
Name=Knobbie
Comment=Custom KDE volume knob daemon

Now it launches automatically every time you log in.

• Reads raw USB HID packets

• Self‑healing: reclaims interface if kernel steals it

• Adjustable volume speed (VOLUME_DELAY)

• KDE‑native volume popup

• Play/pause button

• Next/previous track

• Zero polling — event‑driven

• Runs as a normal user

The knob sends tiny 1‑byte HID packets:

The script:

• Claims the USB interface

• Reads packets from the interrupt endpoint

• Maps them to KDE media keys

• Uses xdotool + playerctl to trigger system actions

It’s basically a user‑space HID driver.

MIT License