topic Re: interupt return location in S12 / MagniV Microcontrollers

interupt return location

ernestsnaith — Thu, 31 Aug 2006 15:46:15 GMT

How can i specify where i want an interrupt to return to when it has been dealt with? I do not want it to return to a calculation it is half way through with old data.

Thanks

MC9S12XDT512 and CW

Re: interupt return location

J2MEJediMaster — Thu, 31 Aug 2006 20:09:10 GMT

Simpliest answer is that you can't. The hardware is designed so that the program resumes precisely where it left off. You could probably tinker with the stack to change the return address, but before going to that extreme, you'd probably be better off redesigning the application rather than thwart man-years of hardware design.

What exactly are you trying to do that requires such a drastic measure?

---Tom

Re: interupt return location

Red — Thu, 31 Aug 2006 21:33:08 GMT

As J2ME said, you could manipulate the return address that is stored on the stack in order to change the return location. I have done this before, although only ever in experimental software. I'm not sure I'd use the same approach for anything serious.

You probably should think of alternatives and consider any side effects of this as it does deviate from what the hardware is designed to do.

Re: interupt return location

ernestsnaith — Thu, 31 Aug 2006 23:42:17 GMT

Ill have a think and get back if i have a problem, just looking for an easy fix.

cheers

Re: interupt return location

Steve — Fri, 01 Sep 2006 05:39:43 GMT

Have a think about using XGATE for the interrupt if this is an issue for you. That way you may be able to avoid the problem all together!