Den 2007-08-29 09:26:52 skrev Richard Prosser : > Morgan, > You've probably already checked and I'm no expert on the 18 series > (never used one) but don't they have prioritised interrupts? Yes, and we use that facility. > Could you be getting a double interrupt No i could not find interrupts being re-enabled, and high pri seem it can not disturb low pri. > & the temporary storage is getting > corrupted in the handler routine? I have checked the generated save/restore sequences for both levels and they seem OK; saving to different areas, and high priority interrup - and only that - use "RETFIE, FAST". /Morgan -- Morgan Olsson -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist