In-Reply-To: <38D98A2F.D4239E0A@dontronics.com>

Don McKenzie <don@DONTRONICS.COM> wrote:
> Other users have told me that you can get some 4Mhz PICs running at 16
> and
> 20Mhz by just putting a 10Meg resistor across the faster cyrstal.

I would expect most PICs to work at these frequencies without any extra
resistor because the 4 and 10MHz parts are exactly the same as the 20MHz
parts and just  haven't been tested at 20MHz.

I can't believe a 10M resistor is going to make much difference. PICs
already have an internal resistor to bias them into the linear region.

If you really wanted you could hook up an oscilloscope and try different
resistors and see which value gave the strongest oscillations.

It'd be a whole lot simpler to just buy a 20MHz PIC though.

Brian Gregory.
briang@cix.co.uk