Lpc2000

At 12:01 AM 4/18/2006 +0000, jayasooriah wrote:
>--- In lpc2000@yahoogroups.com, "relentless_6995" <bobd@...> wrote:
>
> > Turning on WDT for the first time. I was testing it a few different
> > ways. One way involves a Data Abort IRQ. My data abort IRQ falls into
> > an endless loop (on purpose). It seems that when I create an illegal
> > access to trigger the data abort IRQ the WDT never fires. The code
> > enters the Data Abort IRQ, hits my endless loop and sits there
> > forever - no WDT reset! Anyone know why?
>
>It is because the watchdog timer on LPC is not wired to the Reset
>interrupt priority level of ARM7.  Thus the Data Abort exception that
>you are not dismissing locks out watchdog reset.

<snip>
>if I relied on the watchdog to get me
>out undefined situations, but then I only use the watchdog to trigger
>a reset when I want it to.

Well, there are ways of getting into undefined situations that don't 
involve SW.  They have to be guarded against as well.  A watchdog may not 
be perfect and an internal one less so than an external WD but it is part 
of good defensive practice.

>It is not clear if this behaviour in LPC is a design or implementation
>error.

Yikes, if true that renders the WDT useless.  Have you verified this?

I'll have to set aside some time to check it out.


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