Hi Jan-Erik The thing to keep in mind is that the ISR code I'm posting even with the overrun error checking/clearing is working fine as a low priority ISR. (granted I'm including the push to the buffer) It is only when I make it a high priority ISR that problems are occurring. I do have the ISR for the other port working as a high priority and I'm doing all kinds of extra checks there with no problems...also note I do make it low priority when I try the GPS (the simple one) high. Mucho thanks Phillip Things should be as simple as possible but no simpler Phillip Coiner CTO, GPS Source, Inc. Your source for quality GNSS Networking Solutions and Design Services, Now! -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Jan-Erik Soderholm Sent: Tuesday, September 19, 2006 12:17 PM To: piclist@mit.edu Subject: RE: RE: RE: FW: [PIC] Trouble getting my ISR high > I'm not that sure that an overrun is really physically occurring (I do > believe the bit is set because clearing it makes things work) but I > can't think of a way to prove it. Add a test on the OERR bit ? Jan-Erik. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist