I had the same problem before. Turns out to be the
fuse settings. You may want to check them
carefully.....

John


--- James Nick Sears <jnsears@jamesnsears.com> wrote:

> For a dollar or two, you can be free of all of these
> issues with a  
> little powered clock.  Four pins, Vdd, GND, CLKOUT,
> and something  
> else (probably an enable-like function) and you are
> good to go.   
> 40MHz, no problem.  Just set your clock config flag
> to EC (external  
> clock).  Available in through-hole or SMT (actually
> the surface mount  
> version is smaller or at least similar to the SMT
> crystals I used to  
> use).
> 
> I've spent way too much time already in my young
> life fighting with  
> crystal oscillator circuits.  Anything of mine in
> the future that  
> isn't intended for mass mass production (and maybe
> stuff that does)  
> will have a powered clock, unless there is some
> reason not to that  
> I'm not aware of.
> 
> -n.
> 
> 
> On Dec 10, 2006, at 8:11 PM, Bob Axtell wrote:
> 
> > Adam stambler wrote:
> >> Hi, I was wondering if anyone could provide some
> oscillator  
> >> guidance.  I am
> >> trying to run a 16f690 off a 20 mgherz ceramic
> resonator with  
> >> built in
> >> capacitors.
> >>
> >> I think i have all my my programming correct, but
> when I go to  
> >> turn it on,
> >> it does not work.  The oscillator does not start
> up.  However, if  
> >> I try to
> >> measure the voltage with my multimeter and touch
> the Clock input  
> >> pin, the
> >> PIC starts to work.  There is about 2.3V on the
> clock output and  
> >> input pin
> >> .
> >>
> >> Right now i have a 1 mega Ohm resistor across the
> input and output  
> >> leads of
> >> the resonator like the datasheet said for it to
> have. I am running  
> >> the
> >> resonator in HS mode.
> >>
> >> My guess is that my programming is correct but
> there is not enough  
> >> drive to
> >> get the oscillator going.  Unfortunately, I have
> no idea about how  
> >> to fix
> >> the problem.  This is my first oscillator circuit
> which I am using  
> >> for a
> >> school project.
> >>
> >> Anyone have any ideas?
> >>
> >> Thanks,
> >> Adam Stambler
> >>
> > I have never been able to get reliable startups
> with the 20M seramic
> > resonators. The fastest reliable speed
> > for me was 16M. And I love these critters dearly.
> >
> > I believe the phase-shifting caps do not quite
> match the Microchip
> > oscillator. Drop back to a lower speed
> > or tinker with cap values. Incidentally, the ones
> by Murata may run  
> > at a
> > slightly faster rate.
> >
> > --Bob
> > -- 
> > http://www.piclist.com PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> 
> -- 
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
> 



 
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