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INTO interrupt firing all the time?

INTO interrupt firing all the time?

2007-12-17 by Richard Cooke

Hi Folks,

I'll try this question again as my post of Dec 15th didn't receive any
replies.

What would cause the INT0 to continually fire even if the pin was
grounded?  I have the set to trigger on rising edge (MCUCR = 0x03) but
it will keep triggering.  I have also tried to set it to "any logical
change" (MCUCR = 0x01) but get the same results.

Anybody have any ideas why a pin that is grounded would trigger an
interrupt?

Thanks,

Richard Cooke

Re: INTO interrupt firing all the time?

2007-12-17 by Richard Cooke

Hi Zack,

I've grounded it after not being able to figure out why it keeps
firing.  I figured that if it was grounded it couldn't be a hardware
issue.  I grounded it via a very short wire.

Thanks,

Richard

--- In AVR-Chat@yahoogroups.com, Zack Widup <w9sz@...> wrote:
>
> 
> Hi Richard,
> 
> My first thought is that if it's grounded, why are you setting it up
for 
Show quoted textHide quoted text
> use in firmware? Why not just disable it?
> 
> How is it grounded?  Do you have a long circuit trace or wire to ground 
> that might be picking up crosstalk from other nearby lines? Is it 
> "grounded" through another circuit such as a TTL or CMOS chip?
> 
> Zack
> 
> 
> On Mon, 17 Dec 2007, Richard Cooke wrote:
> 
> > Hi Folks,
> >
> > I'll try this question again as my post of Dec 15th didn't receive any
> > replies.
> >
> > What would cause the INT0 to continually fire even if the pin was
> > grounded?  I have the set to trigger on rising edge (MCUCR = 0x03) but
> > it will keep triggering.  I have also tried to set it to "any logical
> > change" (MCUCR = 0x01) but get the same results.
> >
> > Anybody have any ideas why a pin that is grounded would trigger an
> > interrupt?
> >
> > Thanks,
> >
> > Richard Cooke
> >
>

Re: [AVR-Chat] INTO interrupt firing all the time?

2007-12-17 by Zack Widup

Hi Richard,

My first thought is that if it's grounded, why are you setting it up for 
use in firmware? Why not just disable it?

How is it grounded?  Do you have a long circuit trace or wire to ground 
that might be picking up crosstalk from other nearby lines? Is it 
"grounded" through another circuit such as a TTL or CMOS chip?

Zack
Show quoted textHide quoted text
On Mon, 17 Dec 2007, Richard Cooke wrote:

> Hi Folks,
>
> I'll try this question again as my post of Dec 15th didn't receive any
> replies.
>
> What would cause the INT0 to continually fire even if the pin was
> grounded?  I have the set to trigger on rising edge (MCUCR = 0x03) but
> it will keep triggering.  I have also tried to set it to "any logical
> change" (MCUCR = 0x01) but get the same results.
>
> Anybody have any ideas why a pin that is grounded would trigger an
> interrupt?
>
> Thanks,
>
> Richard Cooke
>

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