Martin R. Green wrote:

> I sidestepped the oscillator problem when breadboarding a design by using a
> canned oscillator instead of a crystal.  I have successfully run PIC's at
> 20MHz on one of those white breadboards that normally have too much
> capacitance between pin rows to allow a crystal oscillator to run properly...

I use those breadboards all the time at 20 MHz and down. I've never had a
problem ever with any PIC chip not running just fine. You need neat technique, a
good power supply (although I regularly use batteries), supply bypassing, and a
0.1 uFd cap across the chip for fast chips. I also sometimes put in some load
caps, but only to get the frequency right.

Now, sometimes the thing won't seem like it's going, but the truth is hard: it's
always been a layout or circuit or software bug. Every single chip I've ever
touched worked just fine, even the ones I plugged in backwards. The only PIC
chip I screwed up was with the programmer, and that was by setting the CP bits
by choosing the wrong chip type.

Check your layout; simplify the circuit to test it; check the power supply and
bypassing; use a good cheap crystal from Digi-Key. It'll work.

--Tom Rogers  VP-R&D  Time Tech Inc.