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RE: [avr-gcc-list] Glitch on GPIO


From: Jahagirdar Gopal-AGJ005
Subject: RE: [avr-gcc-list] Glitch on GPIO
Date: Fri, 24 Feb 2006 23:13:09 +0800

Yes, first I am configuring the direction register and then writing data
in to it.
Will this be a problem?
will it work, If we write data first and then configure the direction
register?

-Gopal

-----Original Message-----
From: Galen Seitz [mailto:address@hidden 
Sent: Friday, February 24, 2006 8:38 PM
To: Jahagirdar Gopal-AGJ005
Cc: address@hidden
Subject: Re: [avr-gcc-list] Glitch on GPIO 

Jahagirdar Gopal-AGJ005 <address@hidden> wrote:

> HI,
> 
> I have one peculiar problem here. 
> 
> One of the GPIO of atmega128, has been pulled up. When atmega128 boots
> up, initialization script makes that GPIO pin high, irrespective of
what
> is pulled up (Atmega does not start booting immediately the power is
> given. There is some delay given purposely between power-up and
> execution de-assertion of reset signal). So the expected behavior is
> that pin should continue to be high as measured on CRO. But there is a
> glitch (10us) on that pin when GPIO is written high by software. 
> 
>  
> 
> Any idea on this behavior? Can this be solved?
> 

Are you writing to the direction register before writing to the data
register by any chance?  It would be helpful to see the initialization 
code.

galen




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