On Tuesday 23 Sep 2003 10:25 pm, you wrote:
> Roberts II, Charles K. wrote :
> > I was taught the following convention when it comes to ISR's
> >
> > I have an ISR which monitors the Interrupt bits,
>
> Your ISR doesn't "monitor" anything (normaly). That's
> a "polling" routine and not an "interrupt" driven routine.
>
> > So the ISR is only called when an interrupt signal is received
> > by the micro and causes it to start reading code at specified
> > at the interrupt vector.
>
> This is not what you said above, or ?
> (But is correct.)
>
> Now, what your ISR has to do first is *now* to check the
> interrupt bits to find out *which* interrupt event trigged it
> and then probably jump to some specific "handler" for each event.
>
> Note also that many architectures (not the PICmicro) has "soft-interrupts",
> such as an specific interrupt vector for "illegal instruction" or "divide
> by zero" or whatever. Those are internaly generated interrupts that has
> nothing to do with any external event, but from the ISR's standpoint work
> the same way.
>

And others vector each interrupt to a different address so there is no need to
check which interrupt occured.

Ian

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu