Reduce brightness on all kobo devices / challenge for developers

[akorx]

Hi guys,

First sorry for my bad english, Im' french.

I've got a Glo (not HD) on which I've added a resistor in order too reduce the brightness since 2013 and all is ok still today after 6 years; I was the first person to ask the question and Yok and others guys have found a solution here : https://www.mobileread.com/forums/sh...=200706&page=7 ).

I've got a second kobo (aura HD) and the brightness is too high...

So I've got a question : is there a way with a plugin too reduce brightness on all Kobo devices ? if not, a good solution would be to create a plugin that can divide the setting by 2 or 3 or why not 10, in order to reduce brightness under 1% like 0.1%, 0.2%, etc.
If the brightness slider does not accept a setting under 1%, another solution coud be to mislead the value send to the LEDS (we set 10% on the slider but the real value send is 1%, 9% send 0.9%, etc).

Developers : do you see a solution , it could be a good challenge, no ?

A good add-on is nightmode, it can be found here : https://github.com/gtalusan/kobo-nig...de_build13.zip but it doesn't reduce the level of the leds.

[akorx]

A little up...

[pazos]

Sorry akorx, but the minimum brightness level will still be the minimum brightness level. I cannot speak for newer interfaces, but the classic interface of writting an integer to /dev/ntx_io (which is used by nickel even on devices with natural light) requires a number between 0 and 100, Being 1 the first value which turns on the frontlight.

So it seems something you need to fix with hardware mods, like you did on your Glo.

[davidfor]

Originally Posted by pazos

Sorry akorx, but the minimum brightness level will still be the minimum brightness level. I cannot speak for newer interfaces, but the classic interface of writting an integer to /dev/ntx_io (which is used by nickel even on devices with natural light) requires a number between 0 and 100, Being 1 the first value which turns on the frontlight.

I'm told by someone who should know, that Kobo do the control through the ntx_io ioctl device. Which agrees with that. But, there are some sysfs files that you might be able to tweak.

The minimum levels Kobo have chosen are for stability. If you go lower, you might get flickering or just no light. An individual device might go lower, but, it would need to be tested for each one.

[pazos]

Originally Posted by davidfor

there are some sysfs files that you might be able to tweak.

In fact, KOReader uses sysfs on newer devices:

Aura One: https://github.com/koreader/koreader...device.lua#L74
H2O2: https://github.com/koreader/koreader...evice.lua#L126
H2O2r2: https://github.com/koreader/koreader...evice.lua#L143
Clara: https://github.com/koreader/koreader...evice.lua#L195
...

OP could check if the aura hd has a similar node under /sys/class/backlight and explore its attributes. See https://github.com/koreader/koreader...ment-437626445