Remember that by connecting anything to the xtal pins you will change
its frequency due to capacitance. If you're after the sort of accuracy
you mention, it will be very difficult to acheive it with any sort of
direct connection.
A MUCH MUCH better way to do it is to output a known frequency on a
PIC pin (perhaps in a special test/calibration mode), and measure
this. Most decent frequency counters ought to be able to do this to
the accuracy you require, but you should probably use one with a TXCO
or OCXO reference).


On Mon, 12 Aug 2002 18:12:05 +0800, you wrote:

>We are using a 12.000MHz crystal in a timer circuit. It has 2 x 33pF =
load
>capacitors and the xtal is under the IC socket so the tracks to the uC =
are
>0.15" only.
>
>We want to measure the osc frequency to within 1Hz so we can adjust the
>load cap in one leg. Can someone tell us what test gear we need to be =
able
>to do this?
>
>regards,
>
>Peter Crowcroft
>             DIY Electronics (HK) Ltd
>       PO Box 88458, Sham Shui Po, Hong Kong
>Factory: voice 852-2304 2250    Fax: 852-2729 1400
>          M/F, 97 Fuk Wa Street, Sham Shui Po
>Home: voice 852-2720 0255          Mobile: 6273 2049
>Web:  http://www.kitsrus.com        Email: peter@kitsrus.com
>       Yahoo Messenger  'peter5999'  with webcam
>       Pay with Paypal:  peter@kitsrus.com
>-------------------------------------------------------------

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