AVR-Chat

Hien,
Just a thought.... PIND.0 is shared with RXD on a mega16 - you don't have 
the UART enabled while you are trying to read PIND.0? ;-)

HTH
Ivan Vernot


----- Original Message ----- 
From: "kernels_nz" <hein@mediflex.co.nz>
To: <AVR-Chat@yahoogroups.com>
Sent: Tuesday, February 07, 2006 8:19 AM
Subject: [AVR-Chat] Re: Problem reading PIND.0 on Mega16 with 16MHz Crystal


> Hi Guys, Thanks for all the suggestions, will check the fuses tonight
> when I get home, I think the suggestion that the input is actually
> affecting the crystal instead of the other way round sounds very valid.
>
> Im only checking PIND.0 as general input, and im reasonably
> experienced with AVR's , so dont believe it's a simple code problem.
> As I said, using PIND.0 = dont work, any other one of the PIND pins
> works fine.
>
> THANKS AGAIN ! GREAT SUGGESTIONS FROM EVERYONE !
>
> Cheers
> Hein B
> Auckland, New Zealand.
>
> --- In AVR-Chat@yahoogroups.com, "Dave VanHorn" <dvh@...> wrote:
>>
>> > Could noise from the crystal pin be coupling to the data input
>> > and corrupting the data stream somehow ? could this be happening
>> > inside the Mega16 ? If so it is unfortunate that Atmel have placed the
>> >  RXD pin of the UART right next to the crystal pins.
>>
>> Far more likely that your input signal is disturbing the crystal.
>> If you haven't programmed the CKOPT fuse, then do so.
>>
>> After that, see my other post on checking the oscillator design.
>>
>> There are also possible layout issues, involving how the crystal caps
>> return to the AVR's ground pin. They should do so on an isolated track
>> that connects to system ground only at the AVR pin.
>>
>> > Unfortunately I really do need to use a 16MHz crystal also, so merely
>> > ignoring the problem and using a slower oscillator will not work !
>>
>> On a more mundane note, this may be a code problem, can you detail how
>> it is that you're checking the pin?
>>
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