I have deciphered PWM a little bit, I can see how to calulate a PR2 But I'm not sure what you need to do to get a symetrical square wave, and I don't see how you could get the duty cycle adjusted for 500khz thanks for any help (someone mentioned how to do this a few weeks ago, if you could repost your tips again thanks) (lately I've been deleting my pic folder, it seems to help with not getting distracted by all the posts) -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics