On Fri, 2011-01-21 at 14:28 -0800, Colin Cross wrote: > Clocks that have a voltage dependency, or depend on a clock that has a > voltage dependency, are non-atomic, everything else is atomic. PLLs > are atomic because they lock very fast (300 uS or 1ms) Some could argue that this is still way too slow for atomic context :-) Cheers, Ben.