Re: [avr-chat] Debugging an xmega with the AVR Dragon

[Bob Paddock]

> Does anyone have any experience in this area?  Could the omission of the
> RESET pullup be having some bad effect, like causing communication errors
> that result in the long turnaround times?

PDI is a synchronous system if there is a lot of skew between PDI_CLK
(the reset pin) and PDI_DATA you might get what you are seeing.

I always put a 10k pull up on Reset (to lower its impedance increase
noise immunity not related to PDI), and a 100k pull down on PDI_DATA,
as well as making sure the CLK/DATA lines are matched in length
(timing skew and capacitance) in the layout, and fixtures, as much as
practical.  Has worked fine so far on all my XMega boards.  However I
have not tried to use the Dragon yet.