AVR-Chat

David,

You are right on the 10K - if the current needed to pull up is minimal, the Vdrop over that resistor will be minimal and all is well.  But in a high noise environment (or where there is RF floating about), I like to use lower value pull ups if the sink capability of the driver is sufficient.  And 1K at 5V is only 5ma.  Just about anything connected to that line should be able to sink 5ma.  My 2 cents.

73/jeff/ac0c


From: David Kelly 
Sent: Friday, October 16, 2009 10:29 AM
To: AVR-Chat@yahoogroups.com 
Subject: Re: [AVR-Chat] JTAG problems with ATmega164P


  On Fri, Oct 16, 2009 at 11:44:53AM -0300, Emerson Santos wrote:
> Hi David
> 
> Thanks for you reply
> 
> But i can fix the problem soldering a 1K Pull UP in the TCK line of
> JTAG in the ATmega164P board ... I don?t see anything about this in
> the datasheet but works.
> 
> hehehehe

Wow! 1k is a pretty stout pullup. I'd experiment with 10k.

Last week I briefly fired up a board via Dragon JTAG that was built a
year ago but never run before. Everything went fine until I attempted to
debug. Board immediately took off running but I can't single step or
breakpoint. Didn't have time or need to pursue it then. Meanwhile a
JTAGICE-II was coming in the mail via Arrow's half price promotion.

Next time I attack that problem board I will have a Dragon, ICE Cube,
and the official JTAG-ICE mkII.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.




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