Rockbox mail archive
Subject: Re: serial line interference problems
From: sophana (jobarjo78_at_yahoo.fr)
> Just a couple of wild guesses...
> 1. Have you checked that the line-in is disabled on the MAS?
Yes I checked that, when the line-in is enabled I have a HUGE noise on
the left side. When disabled, the noise is much more lowered but it is
on both sides. I'll have to unmount everything and try to use the ear
> 2. Have you tried the anti-skip buffer to resolve the skipping issue?
No I haven't yet. But where is located this skip buffer? if it is in
dram memory I don't think it will solve anything because I think the
problem is between the dram and the mas (DMA interrupt I think).
What is strange is that I tried raising the DMA interrupt priority
(above the serial interrupt). It make the skipping different but there
is still a skipping.
I had to lower the serial interrupt priority to 4 to make it work.
> Maybe I guess lucky today?
> At 09:45 16/06/04, you wrote:
>> Hi all
>> I did finish the development of my cd changer emulation. But there
>> was one thing I never did during the development: listen to the music.
>> Yesterday, I installed my sony head unit and my archos in my car,
>> then I discovered 2 problems:
>> First there is a very audible noise due to serial communications. I
>> have choosed to use the line-in connector, instead of the ear because
>> of the auto power on mod, to connect the serial line. Does anyone
>> knows if the noise is due to the line-in connection or directly
>> because of the serial line? have people who made the serial mod
>> noticed noise interference during communications?
>> My second problem is partialy resolved: The software tx path that I
>> used was blocking interrupts inside the interrupt handler, causing
>> pops in the sound because of mp3 buffer underruns I think. What I did
>> is lower the serial interrupt level to 4 and allow interrupts during
>> software tx. Now there are no more pops but I have lots of
>> transmission error.
>> Does anyone have a suggestion?
>> I think I will have to connect the serial tx to the rx line so there
>> will be no more interrupt masking.
Page was last modified "Jan 10 2012" The Rockbox Crew