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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


-----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
> 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 


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