Lpc2000

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