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Rockbox mail archiveSubject: Re: Call for translatorsRe: Call for translators
From: Jens Arnold <arnold-j_at_t-online.de>
Date: Sun, 26 Jun 2005 22:29:38 +0200 Hello Manuel On 26.06.2005, you wrote: > On 6/26/05, Linus Nielsen Feltzing <linus_at_haxx.se> wrote: >> BlueChip wrote: >> Backlight fading on the archos was done a looooooooooooong >> time ago. By Amiconn, iirc. >> ...but never committed, because it put too much strain on the >> CPU and I2C, IIRC. > I take this as a no for my initial question :-) Unfortunately it's not possible for mainstream rockbox, however, the reason is *not* the cpu load. Recently I did some more experiments to evaluate that kind of stuff. There are 3 types of backlight and backlight circuitry used in the various archoses: (1) The Ondio family: These are prepared for backlight, but so far we know of no single unmodded Ondio equipped with a backlight. This backlight, if installed by a hardware mod, is controlled by an I/O port pin, but since it is an EL backlight, it's not dimmable. The EL driver chip would need special features to allow this. (2) The Recorder family: These have a LED backlight which in theory is dimmable by PWM. However, the backlight is not directly connected to a CPU port pin, but to a port pin of the RTC. That means this port is only controllable via the I2C bus, which should not be done in interrupts, and doing it from a thread does not allow for precise enough timing. I have an experimental plugin that dims the recorder backlight nicely, but as soon as something else accesses the I2C bus, like playing music which requires controlling the MAS, the unit will lock up sooner or later. (3) The player family: These have a LED backlight with is hooked up to a CPU port pin, so it should be dimmable the same way as the iriver backlight is. I actually tried it, but it does not work. Instead of nicely fading, it just flickers a bit, then goes off. There seems to be additional circuitry between the port pin and the LEDs that prevents nice dimming. It was not the code's fault; I tried dimming the red LED instead which worked like a charm. So unfortunately, no backlight dimming possible on archos :-( Regards, Jens _______________________________________________ http://cool.haxx.se/mailman/listinfo/rockbox Received on 2005-06-26 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |