Maybe I'm coming in late on this one, but...

Is your oscillator oscillating?  Can I safely assume you've tried a
different (lower frequency maybe even) xtal?  It *is* a parallel resonant
xtal and not series resonant, right?

Dale

On Tue, 7 Aug 2001, Ed Troy wrote:

> Incredible!! Even this does not work. I am doing something incredibly
> stupid, but I can't figure out what it is. Either that, or my programmer (a
> Topmax) is totally bad, and saying that it is programming chips, and
> verifying them, but not, and I can't believe that. Basically, I am now
> using a 16F874 chip, because it is quick and easy to erase, and I cannot
> get any code to work, although everything I try works fine in the
> simulator. Also, I have noticed that in spite of putting in a line
> TRISD=0x00, (or TRIS whatever), all ports appear to be tristated and
> sitting at 0, since a 10k pullup resistor easily pulls them to high. The
> only ports on my device that are at 1 are RD0 and RD1, because they are
> pulled up by external pullups. (But, nothing I do can get them to 0.)
>
> At this point, I am suspecting some strange hardware or programmer problem.
> Does anyone have a simple (even as simple as the code attached below), that
> is compiled for a 16F874. All I need is the hex file, and a brief
> explanation of what it does, as long as the hex file is known to work on
> actual hardware? Then, I could load that into one of my devices and see
> what it does on the actual board.
>
> TIA,
> Ed
> At 11:35 AM 8/6/2001 -0700, you wrote:
> >>I have corrected the typo, although that would not have stopped something
> >>from toggling. I checked my circuit, and it is basically the same as yours.
> >>The only difference is that I hardwired ~MCLR to +5 volts. The rise time is
> >
> >
> >etc.
> >
> >I can only offer a few more suggestions:
> >
> >1) Use an even simpler program for the test. e.g.
> >
> >main() {
> >     TRISD = 0x00;
> >     PORTD = 0x55;
> >here:
> >     goto here;
> >}
> >
> >No matter what else is going on in the system, PORTD should get stuck
> >at 0x55, and resets won't affect that.
> >
> >2) Are you sure you're building the application for the 1674B? It
> >might be for another chip ...
> >
> >Regards,
> >
> >--
> >
> >  ______________________________________
> >   Andrew E. Kalman, Ph.D.   aek@pumpkininc.com
> >
> >--
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