Thats the compiler's job. You can tell the compiler to save additional
registers if
you need to.
----- Original Message -----
From: "M. Adam Davis" <adavis@UBASICS.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, November 03, 2000 12:43 PM
Subject: Re: [PIC]: How do I assign functions to interrupts in MPLAB-C18?


> Any time an interrupt occurs in a PIC with the GIE enabled, the code
immediately
> jumps to code at location 4, and places its previous location on the
stack.  (it
> also disables GIE to prevent an endless interrupt jump to 0x04)
>
> That's it.
>
> If you want to assign a function to a particular interrupt, you'll need
code at
> location 4 to:
> 1) Save the contents of status registers, W,
>    and other registers whihc will change in
>    your interrupt function code.
> 2) Check each interrup flag of interest, call
>    its associated function, and reset the flag
> 3) Restore the registers which you saved in
>    the beginning, and return from the
>    interrupt handler.
>
> So you are correct in saying that you'll essentially have to create code
that
> determines which interrupt occured as there is only one location for a
'main'
> interrupt.
>
> -Adam
>
> Jeff Meyer wrote:
> >
> > Hi all.
> >
> > I want to write a program that responds to various interrupts (PORTB and
> > USART specifically).  I have been programming real time systems for many
> > years and use interrupts all the time, and the interrupt model in that
> > environment is one of "connecting" a procedure to a specific interrupt
by
> > defining the procedure and then assigning an interrupt to it
(basically).
> > Is that possible in MPLAB-C18?  I see the "pragma interrupt" directive,
but
> > the examples I see generally have a "main" interrupt procedure that
checks
> > to see what interrupt occurred and then it calls a procedure based on
that.
> > That seems to be the model in the PIC18Cxx2 document as well.  I don't
see
> > a method to assign say interrupts to functions or vice-versa.
> >
> > Thanks,
> > Jeff.
> >
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