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[solved] MintyPi v3 screen brightness control
Posted: Fri May 03, 2019 8:02 am
by oscillope
Hello!
I built my mintyPi last night and so far, everything is working great. There's just one thing I haven't been able to figure out, and that's how to adjust the screen brightness. The v2 build guide mentions that it's available in the OSD menu, but it doesn't appear to be there in the v3 software. I poked around for a bit and couldn't find anything that looks promising. Am I missing something, or is it just not implemented?
Thanks.
Re: MintyPi v3 screen brightness control
Posted: Fri May 03, 2019 8:12 am
by wermy
Unfortunately we found that PWMing the screen brightness had a surprising amount of overhead associated with it, and was making games run a little slower than they should. To us it seemed like a fair tradeoff to remove that and hard-wire the screen backlight, in exchange for better performance.
Some boards like kite's Circuit Sword use a separate microcontroller to handle things like that, so we may look into that in the future; we'll see.

Re: MintyPi v3 screen brightness control
Posted: Fri May 03, 2019 9:50 am
by oscillope
huh, that is surprising! Especially if you're using the pi's PWM pins, I'd have thought the overhead would be near zero. Thanks for the explanation! Is the backlight still hooked up to a GPIO on the pi? Just wondering if it's possible even to have on/off control, to save some power without shutting the whole thing down.
Yeah, separate microcontroller would work... there are also a number of fairly cheep backlight/LED control ICs, some of which already have drivers built-in to the linux kernel. Either way, something to look forward to in v4

Re: [solved] MintyPi v3 screen brightness control
Posted: Sat May 04, 2019 8:46 pm
by Helder
The program required to control the backlight is what was being a resource hog so we decided against it since 99% of people used it. It will return in the future I suppose.