Scott Dattalo wrote: Since the L/C is going to be prone to drift, the PIC could save the last sample and look for too big a jump (up or down) as opposed to a hard-coded setpoint. Thus temperature changes, plate tectonics , etc. would have little effect on the detection of a bump. Just my two pence... Michael * TAKE THE '.NOSPAM' OUT OF MY ADDRESS TO REPLY ********************************************** Outside of a dog, a book is man's best friend. Inside of a dog, it's too hard to read anyway! Groucho Marx **********************************************