At 11:05 PM 10/03/2002 -0500, you wrote:
>...and what can cause my PIC16F84A-20P to work with a 4MHz resonator but not
>a 20MHz resonator?
>
>I have tried two different 20 MHz resonators and the chip doesn't work with
>either...  4MHz is just fine.  The application is a simple LED turn on and
>keep on, so speed should make no difference.
>
>Any ideas?  - Programmed with MPLab and the properties for the project
>specify 20MHz.  XT is specified as the type...

Change the oscillator type to HS for above 4MHz.
Regards...

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