At 04:51 PM 7/14/2005, Wouter van Ooijen wrote:
> > I commonly include a series resistor on the output pin,  for
> > adjusting drive level, and checking oscillator margin.
>
>but how do you determine the value?

The trick is not to put any more drive to the crystal than you really need.
Sub in resistors, till you find the one that reliably starts in all 
your environmental conditions.
(you can use a pot to get close, just keep the leads short)
Cut that value in half.

Do a worst-case check on drive level, making sure that you still 
aren't exceeding the rock's spec.

Various manufacturers have slightly different versions of this test, 
but this is sort of the "average" of them.

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