Hi All:

At the risk of offending the geniuses out there, I have a(nother)
completely dumb question.  I have a PIC application that works
beautifully on a microchip demonstration board, and won't work on my
own.

Tring to isolate the problem, I went back to a simple LED-flashing
program (calculating delays from the main crystal).  On the demo
board, it also works fine, but on my board it flashes irregularly,
seeming to be "beating" with another much slower frequency.  (The
application I am working on has a watch crystal beating a 2-second
period on Timer1, but this appears before the interrupt is enabled.)

So far as I can tell (the 30th time through), the pins are all
connected to the right power.  MCLR is tied to 5V through a 4700ohm
resistor.  I am using a 16C74.  The watchdog timer is disabled, and
there are no interrupts enabled (yet).

There is a 16x4 LCD attached to this all (works on the demo board, but
doesn't initialize on mine), and I wondered if it was pulling the
power down.  I haven't been able to detect this, but my test equipment
is pretty rudimentary.  What would a pic do that was flirting with the
brown-out protection?

I am not expecting anyone to be able to diagnose my problems remotely,
but I wonder if anyone who remembers their early blundering could jot
down a list of the dumb things to check.  I need more things to try,
since I've run out of the things I know about.  I feel like I am
overlooking something right in front of my face, but I can't tell what
it is.

I am more or less at my wit's end (an alarmingly short distance), or I
shouldn't have risked bothering you.  Many thanks for any help or
advice at all,

-tom

p.s. Many thanks as well for the help I've already been given, both to
questions directly asked, and for help rendered to others in similar
trouble.  I'm learning about PICs on my own, and I don't have anybody
here to ask these questions, and to provide reality checks.  This
makes this list a remarkably valuable resource, despite the goats,
dutch humor, and other distractions.

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tomss at ids.net - 401-861-2831 - 42 Forge Rd, Potowomut, RI 02818 USA