Lpc2000

At 05:45 AM 4/22/06 +0000, johnthomasedwardtimm wrote:
>We are experiencing the same problem as your in your message, our
>code is structured similarily to yours, and we have the FIFO turned
>on.  Changing our "while" loop to an "if" statement, as you did, has
>alleviated the problem.  The errata states that if MSR interrupt is
>turned off, which it is in our case, then the THRE interrupt is
>lowest priority.  We only have two interrupts configured THRE and
>RDA.  As per the errata, if we read the IIR and it is a THRE, we are
>okay in that it won't clear a pending RDA that occurs during the
>read.  If we read the IIR and it is an RDA we should get the RDA and
>a pending THRE will come in as a separate interrupt because reading
>the RDA is non-destructive.  When using the "while" loop we are
>reading multiple times possibly clearing a THRE interrupt
>inadvertantly when reading second time after RDA to check for
>additional interrupts.  It appears, that as per the "workaround" in
>the errata and the example code that philips generated themselves,
>the read-the-IIR-once-and-only-once method you came up with seems
>like a realistic workaround to the problem.  Obviously we need more
>testing but we were getting it to fail every 10 minutes or so.  It
>has now run for hours and we intend to run it all weekend with heavy
>data traffic in both directions.

Interesting, it sounds like something more than just a FIFO bug is going 
on.  What errata are you referring to?  I don't remember a serial port 
errata but I may have missed it.  The only tests I'm aware of are like 
yours, heavy data traffic.  That gets some idea of probability but I'd like 
to get something more definitive.  Without a better idea of the root cause 
though I'm not sure what to try.

If you hear back from Philips let us know please.  I'd like to get a better 
handle on this.

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,   be 
they legal, genetic, or physical.  If you don't believe me, try to chew a 
radio signal. "  -- Kelvin Throop, III
http://www.aeolusdevelopment.com/