On Fri, Jul 18, 2014 at 06:38:42PM +1000, James Cameron wrote: > Exactly. What you haven't yet said is how accurate you want the pulse > to be, and what else the microcontroller is going to be doing. Oh, hang on, you said less than 1ppm. What's your crystal spec? --=20 James Cameron http://quozl.linux.org.au/ --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .