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

[Galen Seitz]

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