>Method 1:
>Let the piece of code stay within a while loop and make sure there are no
>other processes that can interrupt it.
>This could be bad because there may be other tasks that needs attention.

This isn't really a good idea.  If you let it be interruptible, it would be
ok, but since it's supposed to be realtime, that's not good.

>Method 2:
>Create a timer that has the highest level of interrupt priority.

This is a much nicer method.

>Is there any C function within MPLAB C18 compiler that caters to real-time
>processes?

Ok, so you're using an 18-series PIC, which definitely makes it easier to
implement this.  I would recommend using the Tmr0 overflow to  keep your
real time thread happening.  And make it a high priority interrupt.  Try to
keep your other high priority interrupts to a minimum.

>As a general guideline, should the highest priority be assigned to those
>"more important" routines with long execution time or to those routines
>which can be executed to completion in the shortest time?

You can debate over this a lot, I think it comes out to two different
schools of thinking.

--Brendan

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