Lpc2000

At 02:15 PM 11/18/04 +0000, you wrote:
> > Leighton's symptoms appear to be similar to (but not the same as)
>what I've
> > seen so I'm wondering if he hasn't run across the same underlying
>problem I
> > have.
> >
> > The THRE interrupts are the only serial interrupts that do not re-
>assert if
> > they are not serviced so they are particularly vulnerable.
> >
>
>Robert, I haven't yet seen the problem you described that's
>interestingly the opposite to what I'm getting. Debugging through
>the JTAG and using a serial port data logger I see all the receiver
>bytes coming in from the PC. I usually send up to 16 bytes per THRE
>& for the most part the lpc sends the reply packet correctly. But
>only in that special case I see the lpc not respond to the last
>command packet. It came across the receive line ok (logger) so the
>PC's ok. However on the lpc side I debug and see the packet looking
>truncated. Like some bytes got lost while receiving, which looks
>kinda wierd. I haven't yet seen the opposite happen b4.

I had a thought.  If my speculation about a race condition in IIR is 
correct it may well explain both our problems.  In my case I lose the THRE 
interrupt and thus stop transmitting.  In your case you lose a receive 
interrupt and drop a character.  My test wouldn't catch a dropped character 
since I wasn't running any sort of check or comparison so all I would see 
is if the echo stopped cold (if a receive interrupt was missed it would 
just pick up the next one).

Do you know (and can you tell) if the packet is truncated or maybe just 
missing characters from its body?  If it always just characters at the end 
I'm less optimistic about the race condition.

If it is a race in the IIR then a single read per interrupt might help (or 
it might not) depending on the details of the race and the timing (ICK).

In any case let us know how changing to a single IIR read per interrupt 
affects the problem.


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