Lpc2000

Dear Brendan,

It looks like you are asking for help, yet put on an air and this makes it 
difficult for anyone to help without a sour taste in the 
mouth.  Nonetheless I shall try to oblige ...

My solution for the UART DOES work and HAS BEEN ADOPTED by clients who will 
not tolerate spurious interrupts in their systems.  It depends on what the 
are is being used for its its limitation in relation to transient behaviour 
of its RDA/CTI interrupt sources.

If you recognise that it has a FIFO in the receive channel, and you have 
suitable timers operating in your system, you can poll the UART using these 
timers.  The most important point to note in any solution (from a spurious 
interrupts perspective) is that it should not result in the generation of 
spurious interrupts.  Hence I consider the work around given in Philips 
AN10414, which I believe is what you are proposing to do, not a solution.

If you allow transient interrupts into your system the problems you need to 
entertain may not limited to just spurious interrupts of the type that I 
demonstrated by way of experiment.  You have to look at the design of PL190 
itself to understand what else can happen.

Interim information I have suggests that PL192 can handle interrupts that 
exhibit transient behaviour by design.  You will note it does not have any 
default vector.  So one solution is to wait for the next iteration of 
silicon and hope Philips will incorporate PL192 -- you have to ask Philips.

The other solution is to look for other ARM variants after checking if they 
incorporate PL190 VIC (it has a default vector) and run the experiments I 
have provided on these to see if the same problem manifests on these other 
systems.

If you need further comment on your particular work-around, I recommend you 
seek professional advice.  This is as far as I am prepared to go in 
relation to free advice for your particular problem.

Kind regards,

Jaya

>Message: 14
>    Date: Wed, 22 Mar 2006 14:57:03 -0000
>    From: "brendanmurphy37" <brendan.murphy@...>
>Subject: Re: spurious interrupts on LPC
>
>
>Jaya,
>
>I've no interest in politics, nor in proving or disproving what you
>say.
>
>The point I was making (repeatedly!) is that your "solution" for UART
>related spurious interrupts is in fact no solution, as it simply says
>don't use the relevant interrupt. This isn't very practical.
>
>I've also asked you (again, repeatedly) for information on why you
>claim having an empty default interrupt handler won't work. I'm very
>interested in this, as it's currently in use; if it's likely to fail,
>I'd like to know about it.
>
>Having said that, I would imagine most people are extremely tired of
>this topic at this stage, so if you don't want to answer, I'm sure no
>one will mind. I'm certainly happy enough to stop right now.
>
>Keep up the good work.
>
>Brendan

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