AVR-Chat

dlc wrote:
> Not uncommon with AVR's in my experience.  I have yet to get a board 
> designed that didn't have problems with resets on an AVR or MEGAAVR 
> part.  I've found that if I run the part at its maximum rated frequency, 
> I get flaky boards, if I derate by 20% or so then the board gets more 
> reliable, and if I derate by 50% the clock speed everything works fine. 
>   This seems to indicate that I've got noise on the clock lines - but 
> after my first experience with these things I've started designing with 
> guard rings on my oscillator circuits, whole plane grounds, bypass caps 
> up the nose, low pass filters on my VDD and everything else I've found 
> in app notes on the Atmel site, still I can get flaky boards.  I never 
> have these problems with PICs <did I say that?>.
> 
> I love these chips, they have speed, capability and low cost.  But oh 
> the problems with Atmel availability and quirkyness.
> 
> IMO, YMMV,
> DLC

If you want to first check your CKOPT fuse (the default is UNCHECKED, 
CHECK IT!!!!) that will fix a lot of problems.

OK if you want to send me the pcb and schematic I can check over, as I 
have NEVER HAD flaky AVR boards since setting the CKOPT fuse :) I have 
over 300 ATMega128's in the field right now, (the only problem ones are 
the ones that have not had the fuse ticked (someone else programmed them 
lol) (but they are coming back as we take them all to the current 
revision (some hardware mods and firmware upgrades)

-- 
Regards,

Kat.
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