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RE: How to Disable FIQ on AT91 (eg EB40A)


> From: Keith Ross (E-Lands)
>
> I have noise on my unused FIQ pin and no handler, so my stack keep full,
> etc when I run my app but ok when single step. The question is how do I
> disable FIQ or what do I do to intall a safe handler.

Set bit 6 in the CPSR. (This cannot be done in user mode.)

I don't understand why you'd get stack overflow, though. When an FIQ is
handled, it automatically masks further FIQ interrupts until the handler
returns, so the interrupts can't nest unless you explicitly reenable FIQ
inside the handler.

In the long run, you should really tie off the FIQ pin. Floating CMOS inputs
are not a Good Thing.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com


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