Unhandled ISR is executed for no apparent reason.

[ahoysala]

I'm using a MCF52235 along with "Processor Expert" under CW. For some reason, this project executes the unhandled ISR "Cpu_Interrupt" from "CODE\Cpu.c after PE initialization is complete in the main(). In the PE, I've enabled only the GPT0,1 and 2 timer ISRs and when I run it, the common unhandled ISR "Cpu_Interrupt" executes everytime I try single stepping through the code. Any idea why?

[RichTestardi]

If you have two or more ISRs programmed for identical levels and priorities, you'll get what look like random interrupt vectors being hit.  See http://forums.freescale.com/freescale/board/message?board.id=CFCOMM&message.id=6266#M6266 for how I got bit by this. :smileyhappy:

Otherwise, when you are in Cpu_Interrupt(), can you tell us what are the top two words on the stack, pointed to by A7 and A7+4?  That will tell you the interrupt vector you took, and from where, as defined in section 11.1.2 of the ColdFire Family Programmer’s Reference Manual .

-- Rich

[ahoysala]

Solved, it was exactly the reason. As I did not enough time to go through the datasheet in detail before I got to working on this project(you know every project is wanted yesterday), I slipped on this and in future may slip on others others as well. I will make it a point to pull out time and go though the data sheet to avoid such happenings.

Thank you very much.