I found the same to be true with the 16F876.  I have a 3.6864MHz Crystal
with 18pF loading caps tied to ground.  If I program it to XT (recommended
in the data sheet) it will run about 25% of the time.  HS works like a
charm.  Anyone else have this experience too?  I thought I might have the
wrong loading caps, but they seem correct for the osciallator according to
the app note.

Good luck!

At 09:37 PM 4/12/00 -0700, you wrote:
>I am adding an A/D capability to an existing controller design. This
>involves migrating from a 16C54 to a 16C710.
>
>There seems to be a big difference in the robustness of the
>oscillator. In both cases, I'm using a  2 MHz Matsushita resonator
>with built-in caps and the config choice set to XT. The 16C54 is
>pretty bulletproof. You can hook a scope probe or a logic probe to
>OSC1 or OSC2 and it keeps right on going. The 16C710 quits at the
>slightest loading. That makes me worry about possible stability
>problems and frequent unwanted resets.
>
>Just to see what would happen, I programmed a 16C710 to use the
>config choice HS. Big improvement. Now it acts like the 16C54. But HS
>is not normally the config setting for a 2 MHz part.
>
>Anyone have any comments/suggestions/guidance?
>
>Reg Neale


Erik Reikes
Senior Software Engineer
Xsilogy, Inc.

ereikes@xsilogy.com
ph : (858) 535-5113
fax : (858) 535-5163
cell : (858) 663-1206