Osama wrote:
>the *ACTUAL* code is at the uni (closed Thursdays and Fridays :(  )  i'll
>get it on Saturday and post it...
>
>it does run on the simulator. (this is what puzzles me most! shouldn't
>MPSIM be fully compatible with the real thing?)

What I mean to say there are a lot of cases where the simulator seems to
indicate that something is working, but when you get out into the real
world, it upchucks.

Last year, I spent about three weeks trying to nail down a problem that
worked fine in the simulator, but when I actually tried it out on hardware,
the device just sat there and did nothing.  I finally traced the problem to
how I was simulating it, I had a delay routine that I skipped over in the
simulator because it took about an hour and a half to run (it delayed the
PIC for about 3 seconds).

The problem ended up being that the interrupt routine that I was debugging
was active during this delay, but needed variables which were initialized
*after* the delay routine.  It worked fine when the delay routine was
skipped and the interrupt didn't happen until after the variables were
initialized, but wouldn't work at all when the delay routine was working.

It didn't matter how hard I stared at it - it worked fine in the simulator
and wouldn't work in the device.  Maybe this is a case that would be
immediately obvious if you had an emulator.


Just reviewing this and realizing there is one MAJOR difference between
MPSIM (and MPLAB-SIM) and a real PIC.  That's in how the registers come up
initialized.  In both simulators, they are initialized to 0x000 and in the
PIC, they can be anything.

I just went back to your original note and I'm thinking that this is
probably your problem.  In the code you wrote, you didn't show how the PWM
variables were initialized.  I suspect that you probably don't initialize
PWMCounter (because it shows up as 0x000 in the simulator) and when you run
your code it's actually greater than the test values (and nothing ever gets
output).


Just a question for everybody who's used a PIC emulator more than I have
(because I didn't think to look for this when I was lent a PICMaster), what
do the Register Values initialize to?


When you get the code, we should be able to find the problem,

myke
>
>thanks.
> ----
>From: myke predko <myke@PASSPORT.CA>
>To: PICLIST@MITVMA.MIT.EDU
>Date: 15 May 1997 23:46 PM
>Subject: Re: TMR0 interrupt (PIC16c84 and PWM)
>
>>Osama,
>>
>>Could you please post the *actual* code?  I find that little problems in
>>assembler that screw up the whole program can be stared at for hours by
>the
>>author without seeing them.
>>
>>As well, have you run your code through the simulator (my first line of
>>defense/verification before I burn a part)?
>>
>>myke
>
>

"My ancestors didn't spend millions of years clawing their way to the top of
the food chain, just so I could become a vegetarian"