> mainline code must complete, ISR must complete OK, got it now. So if watchcat is not inverted twice to its original value then a WDT timeout results. That could cover any number of routines, perhaps by addition to watchcat, to a test value -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist