Control for the keyboard backlight

[ml31415]

Firstable, big thanks for putting effort into this, which would basically have been logitechs task. I suppose the backlight of the keyboard should be possible to control in a similar way? If so, it would be great to have it integrated here.

[themech]

Hi. First, thank you for your nice words. I've made the tool for myself but of course thought others may want to use it as well.
I'd like to understand your request better. So my little app covers the first of the options offered on Windows/MacOS. When you connect the keyboard, it configures the behaviour of the Fn keys:

If I understand correctly, you're asking for the last option from this screenshot.
According to the doc it just shows you a notification but does not allow you to control the backlight:

screen overlay notifications will appear temporarily when the K811 keyboard encounters one of these two conditions...Keyboard is in a brightly lit environment/Keyboard battery is very low

The backlight itself is controlled by the F8/F9 keys.

[ml31415]

Well, not really. What I was looking for is the possibility, to permanently store the state of the keyboard backlight. As I'm writing freely without looking on the keyboard, having the backlight on is just a waste of battery, so I'd like to store, that the backlight is always off, when I switch on the keyboard.

I'm not sure if this is indeed possible. I just reread the doc and it just mentions, that the automatic light mode is on, after every restart of the keyboard. I had thought, that I'd read something about a software option, but can't find that anymore right now. Though, that might be an undocumented feature as well.

[themech]

@ml31415 well, this is tricky. The question is - is there a "magic" sequence that, when sent to the keyboard, sets the backlight. When writing my tool for the fn-keys, I connected the keyboard to mac and was listening to the communication between the Logitech Easy-Switch tool and my k811 keyboard. And that's how I found the fn-keys control command and wrote my tool for Linux.
The Logitech tool can read the change in backlight setting but does not allow you to control the backlight of the keyboard so it is hard:

• maybe such sequence of bytes does not exist
• if it exists - how can we find it if no other tool uses it and there is no documentation about it

I've tried to look around for a solution and could not find anything useful.

[ml31415]

That's indeed bad news. We might try to contact logitech and just ask, though I'm a bit pessimistic about an answer.