Thanks for the suggestion. The alternate programming pins can only be used with low voltage programming, and if I'm not mistaken you can't do in circuit debugging with low voltage programming enabled. I know I could just pick a different chip, but I'm a college professor preparing course materials and it would involve quite a lot of changes at this point. I know I should have checked this early, but I never would have thought that they'd have an external interrupt pin that wouldn't work with the in circuit debugger. Any suggestions would be appreciated! John Hansen On Wed, Jun 18, 2014 at 1:02 PM, wrote: > > For some reason on the 16F1459 Microchip has chosen to put the external > > interrupt on the same pin as the in circuit serial programming clock. > > Are you attempting to debug while plugged into the USB? IIRC Microchip > have made the USB pins alternate debug pins the same as the 18F14K50. As > doing any debug will interrupt USB operation this may be a way out for yo= u. > -- > Scanned by iCritical. > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=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 .