Lpc2000

Well as the original poster I have some more news - the WDT does 
fire off a reset while the code is buried in an IRQ. For yet 
unexplained reasons the WDT that I had working appeared to no longer 
be getting activated. I took the few lines of code involved apart 
put them back together and walla it began working again - but I'm 
suspicious - best I can tell I have the exact same code again and 
now it works. It's like the WDT got jammed up into some mode where I 
couldn't start it (as whacked as that sounds)??

With WDT working again, I proceeded to purposely cause the DATA 
ABORT IRQ where the code gets trapped in an endless loop and indeed 
the WDT RESET does go off to start app over again. So that is the 
good news.

--- In lpc2000@yahoogroups.com, "jayasooriah" <jayasooriah@...> 
wrote:
>
> Hi Andrew,
> 
> --- In lpc2000@yahoogroups.com, "Andrew Berney" <amb@> wrote:
> >
> > By my understanding of the original problem he said he is 
deliberately
> > causing a data abort exception to be raised and while processing 
this
> > exception has created an endless loop.
> 
> Yes you are right in that this is what the original post that 
started
> this thread seemed to suggest.  I responded with what I thought was
> going on based on what I know about the six ARM IPLs.
> 
> > Now by my understanding of the Philips LPC's they are only 
capable of
> > dealing with single IRQ's. I.e. they have no ability to stack 
IRQ's and
> > branch from within a current IRQ to service one that is a higher
> priority
> > automatically (you could always do this yourself inside the IRQ 
if you
> > wanted to I guess).
> 
> I was not aware of this limitation.  Are you sure?  Is this stated
> anywhere?
> 
> > It strikes me that this being the case he will never actually 
fully
> service
> > and clear the original IRQ to allow an update of the CPSR, he'll
> simply sit
> > inside it forever and as such it doesn't really matter how many
> other IRQ's
> > fire as he'll never get back to a state whereby the CPSR reflects
> that he
> > has a new IRQ to do something with - hence his WDT will create a
> reset IRQ
> > which will never get actioned...
> > 
> > Is this not what we're seeing here or did I misunderstand 
something?
> > 
> > I'll have to have a quick play with a device and see if I can 
replicate
> > this.
> 
> I would be interested in what you find out.  I do not have my jig
> handy handy at the moment.
> 
> Jaya
>