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rygD

Nihilistic Mystic
Joined
Feb 28, 2014
Messages
7,446
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Everywhere
Ah that wouldn't work, as when you let go of the brightness button, whatever controls the volume will notice that the wheel has moved... it could be used for only one function at a time. Yes, volume makes the most sense for most people, but there may be other creative uses for it.
There is that. And the brightness thing was more for my personal use, not for general use by everyone. I would share whatever I did with that if it wasn't a super simple process (then again, if it isn't a super simple prices it probably wouldn't be worth my time, so I would stick with default brightness controls).

If someone will send me a Pyra I can figure out which of my stupid ideas are worth working on. ;)
 

stevenc99

Still Fresh
Joined
May 10, 2016
Messages
87
So, I think I figured out exactly how the analog wheel for volume works:

https://github.com/goldelico/gta04-kernel/blob/c1ea22da6773595ddfeac2c389031cc794bdb31a/Letux/root/volumed
is an example of reading the wheel's position every 0.1 seconds, and adjusting some output mixer volumes (in 1% steps) whenever the wheel has moved. It probably could be rewritten much better (smarter polling interval, hysteresis, and maybe having smaller than 1% volume steps?), but it should work exactly as desired (adjusts the volume, and works properly after suspend/poweroff).

The wheel is a potentiometer, adjusting voltage within the range 0-1250mV into a General-Purpose ADC on the TWL PMIC chip. The datasheet for the actual chip on the Pyra is only available under NDA I think, but its OMAP3 predecessor, TWL4030 (functionally identical to http://www.ti.com/product/tps65950) had GPADCs that are 10-bit, suggesting it should read the volume wheel's position with as many as 1024 steps. It can also sample very fast, less than 1ms.

So it should be very good quality, and if desired could be very easily reassigned to some other purpose than volume control.
 
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