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+--- Thread: What is the PWM frequency of the panel brightness controller? (/showthread.php?tid=7730)
What is the PWM frequency of the panel brightness controller? - User 12559 - 07-22-2019
I have already written all the details in the „Tick Tock goes the clock“ thread in the news forum, so I‘ll go with the short version here. If you need more information, links or whatever, feel free to ask.
At the time of the July update, I already asked Lukasz for this, who gave me a very detailed specsheet of the IPS panel from BOE used (6 bit colours, 800:1 contrast ratio, 250 nits (cd/m2) brightness, so do not expect anything amazing that will blow you away) on IRC. However, it stated that the PWM frequency could be anything between 200 and 10000 Hz (so anything from terrible to amazing), and reviews of laptops with the same panel showed that it was indeed not dependent on the panel, but rather on the laptop, with devices between 200 and 1000 Hz (the latter one being still suboptimal). All this lead me to the conclusion that the brightness controller is not fixed to the panel and depends on the device manufacturer, in this case Pine64. That means that there should be some hardware engineer (or so) who knows whether it is an analog (which I wouldn‘t mind) or PWM (which I also wouldn‘t mind, if the frequency is high enough) brightness controller, and, if it is the latter one, at which frequency it operates (or who is at least able to find out). If you are such a person, I would be thankful if you could answer my question. I suppose this is a better subforum than where I originally asked.
RE: What is the PWM frequency of the panel brightness controller? - ayufan - 07-23-2019
Currently, it is configured to 1.3kHZ, but this is something that can be tuned.
RE: What is the PWM frequency of the panel brightness controller? - mala - 07-23-2019
That's a bit of good news, thank you.
Is the frequency the same over the whole brightness range, or is it eg lower at lower brightness?
RE: What is the PWM frequency of the panel brightness controller? - ayufan - 07-23-2019
I guess that this is the frequency, and you change the pulse width with different brightness levels.
RE: What is the PWM frequency of the panel brightness controller? - User 12559 - 07-23-2019
(07-23-2019, 02:21 AM)ayufan Wrote: Currently, it is configured to 1.3kHZ, but this is something that can be tuned.That’s not too bad, thank you. How can it be tuned? By the user, e.g. through software? Or is it only factory adjustable? If it is the former, what is the max frequency one can select? According to a Notebookcheck article I once read, most problems should vanish above 500 Hz, and some can still occur up to 2,5-3 Khz (although I am not sure if I actually suffer that much from PWM flickering to have these problems as well).