A while ago, I treated myself to a new solar-powered Logitech keyboard for my computer at work. The keyboard comes with the so-called "Unifying Receiver". This allows up to six devices to be used wirelessly while occupying only one USB port. Communication can also be encrypted (I have not tested that yet). With just one device, communication worked straight away for me. However, adding a second device no longer works automatically.
Fortunately, in the Linux community there is (almost) always a suitable project with people who have, or have had, the same problems. In this case, I very quickly found the "Soolar" project.
Solaar
Soolar allows multiple devices to be used, includes a few settings, and displays battery status. For my solar-powered keyboard, it also shows whether the keyboard is currently charging or discharging and how many lux are available.
Installation under Ubuntu is via a PPA.
sudo apt-add-repository ppa:daniel.pavel/solaar sudo apt-get update sudo apt-get install solaar
Afterward, you can use the command line to test whether a device was found.
solaar-cli show
In my case, there was a problem with permissions for the device /dev/hidraw2. Fortunately, I was able to solve it quite quickly by giving udev a rule for access.
To do this, create the file /etc/udev/rules.d/99-hidraw-permissions.rules with the following contents:
KERNEL=="hidraw*", SUBSYSTEM=="hidraw", MODE="0664", GROUP="plugdev"
After a reboot, Solaar immediately displayed the keyboard and my new mouse in KDE.
In my case (only one device connected), the CLI tool now outputs the following:
Unifying Receiver [/dev/hidraw2:8CD99089] with 1 devices 1: Marathon Mouse M705 [M705:7A8AD0B4]
I hope my little blog post helps a few people.