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Subject: Re: serial line interference problems
From: sophana (
Date: 2004-06-17

I've solved my problems.
It was the line-in which caused a problem, even if disabled. What I did
is simply cut the original line-in wire.
For the skipping, I changed serial interrupt prio to 8, and disabled
interrupts while transmitting inside the interrupt. It works fine. (I
also raised the DMA int level to 13 but I don't know if it is useful)
There may be some interrupts that I dont know which caused the skipping
I heard.

BlueChip wrote:

> Just a couple of wild guesses...
> 1. Have you checked that the line-in is disabled on the MAS?
> 2. Have you tried the anti-skip buffer to resolve the skipping issue?
> Maybe I guess lucky today?
> BC
> 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.
>> Regards
>> Sophana
>> _______________________________________________
> _______________________________________________


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