The core of this solution is thanks to https://www.gilesorr.com/blog/powermate-on-linux.html who modified the work of https://m0aws.co.uk/?p=2201

Griffin Powermate on Linux

The Griffin Powermate is a USB knob that can be used for various purposes. Originally marketed as a volume knob, you can map it to any function you like. (I use it as a mouse scroll wheel for my non-mouse hand.)

Overview

This solution uses the evtest program to read the input from the Powermate and then uses dotool to simulate keyboard/mouse events.

This repo contains:

• powermate.sh - a script that reads the Powermate input using evtest and sends mouse/keyboard events via dotoolc
• dotoold.service - starts the dotoold daemon that listens for commands from the dotoolc client program.
• powermate.service - starts the powermate.sh script as a user service.
• 99-powermate.rules - a udev rule that starts the powermate.service when the Powermate is plugged in.

I developed and tested this on Arch Linux with the Wayland display server.

What if I'm not using Wayland?

If you're using Xorg, you can use xdotool instead of dotool.

What if I'm not using systemd?

Yeah. I don't love it either. You can do all of this from udev.

Instead of starting the service with systemd, you can start the powermate.sh script directly from the udev rule.

You'll also want to write a script that kills the powermate.sh process when the Powermate is unplugged and run that script from the udev rule for the remove action.

Installation

Install evtest and dotool (or xdotool) for your distro.

Create the systemd user directory:

mkdir -p ~/.config/systemd/user

Copy the services to the systemd user directory:

cp *.service ~/.config/systemd/user/

Copy the powermate.sh script to ~/bin/ (or /usr/local/bin or wherever you prefer):

cp powermate.sh ~/bin/

Copy the udev rule to /etc/udev/rules.d/:

sudo cp 99-powermate.rules /etc/udev/rules.d/

Configure

Double check the idProduct and idVendor in the udev rule to make sure they match your Powermate. Use the following command to find the idProduct and idVendor:

udevadm info -a -p $(udevadm info -q path -n /dev/input/by-id/usb-Griffin_Technology__Inc._Griffin_PowerMate-event-if00)

Edit the .service files to point to the correct paths for powermate.sh and dotoold.

Edit the udev rule and put your username in place of <your-username>.

Enable and start the udev rule and systemd services

Reload the udev rules:

sudo udevadm control --reload-rules
sudo udevadm trigger

Enable and start the systemd services:

systemctl --user daemon-reload
systemctl --user enable dotoold.service
systemctl --user enable powermate.service

Usage

At this point, you can either:

• Manually start the services with systemctl --user start dotoold.service and systemctl --user start powermate.service
• Log out and back in to start the services automatically

Debugging

To see what's going on with the powermate.sh script, you can run journalctl --user -u powermate.service -f.

And to see what's going on with the udev rule, you can run sudo journalctl -f -u systemd-udevd.