Re: Exception Trouble

Fred,

You are right that initializing a port inside an ISR is undesirable. I did
not have a hand in the hardware design. I am working around that fact that
the interrupt is the NMI. I need to be able to turn it off and continue
execution before the interrupt is unmasked. In the 68331, I can only
re-initialize the port so the NMI pin becomes an input. Then the input
needs to be polled to determine if it really is a power down or noise on
the NMI. Anyway, I need to re-initialize the port so I can exit the
exception and (optionally) continue processing. It's a long story.

> true # do-powerdown? AB W MOV

Yes, that would work for a varible. I'm using a value for historical
reasons. Originally do-powerdown? was a routine that returned a flag. For
reasons of expediency I changed it to a value so I wouldn't have to change
all my do-powerdown? instances to do-powerdown? @ instances.

Noel

On Thursday 09 September 2004 08:03 am, you wrote:
> Hi Noel,
>
> Without knowing exactly what code is being generated by
> in powerdown , I would guess that you are not saving
> enough registers.
>
> Philosophically, initializing a port inside an ISR is
> unusual and perhaps even undesirable. Could the
> ISR be reduced to:
> true # do-powerdown? AB W MOV
>
> which as I recall requires no registers to be saved.
>
> Regards,
>
> Fred Carter
>
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-- 
------------------------------------------------------------------
  Noel Henson
  www.noels-lab.com	Chips, firmware and embedded systems
  www.vimoutliner.org	Work fast. Think well.
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