At 10:18 AM 8/25/99 +0200, John Bes wrote:

>- connection:
>
>        GND
>       __|__
>     _|      |_
>     _       _ 2x C=47pF
>      |       |
>      |_|X|_|
>      |      |_
>      |     |  | R=10 Ohm
>      |     |_|
>      |16   |15
>   _ |____|______
>   | Pic 16c84    |
>   ---------------------
>

I don't know the specifics of the specs for your xtal, but what I used for
my 4Mhz crystal was : 10pF for the two load caps and no series resistor.

It seems to me with such big load caps and the additional load of the
resistor that maybe its having trouble starting out.  I don't know dick
about crystal design so I just guessed with my values.  I seem to remember
somewhere reading that the load caps should be 2x the capacitance of your
crystal, so mine should probably each be 20pF's.  I also read that the load
caps weren't too critical as far as value was concerned as they don't add
much in the "filter effect" of the extra components.  It seems to me that a
series resistance would change the freq. response of the system quite a
bit.  I'd first try just chucking the resistor.

Ohh yeah, also double and triple check that your MC reset line is being
pulled high.  This will stop you dead in the water if its floating.

Good luck.

The way I figured mine out was to look at the spots for components on my
proto board and to read the Mchip app note on this stuff.  Its on their web
page in the app note section I believe.

-E