6 Mhz Oscillator

[sebastien]

Hi,

I've aquired a card with a pic 18f8720 on it, so far so good.
The model is supported etc, but that card has a 6Mhz crystal.
And when i consult the PBP manual i see that supported oscillators are 4 and 8, etc

Is there any work around for this?
Should I change the cristal on the card ? Go for 10, 8 or better 4 ?
(yekes, card is compact and double sided)

Run it with OSC 4 ?
I need to do some I2C later on, will that have any side effects ?



Regards

[Acetronics2]

Hi, Sebastien

IF you intend to use PBP ... I would recommend you to simply enable the HSPLL mode ( 4x Xtal frequ. ) ... in the Chip CONFIG lines.

You just will have to declare 24 Mhz as a clock frequency ( DEFINE OSC 24 ) ...

the only backdraw will be for " slow PWM " generation ... 1465 Hz will be a minimum ! and some little limitations with the Pulsin, RCTime ...not frequency compensated command.

No need to modify your card, then ... if 6 Mhz is not in use for another chip on the card !!!

Alain

[sebastien]

I never heard about the HSPPL, this explains why this card is delivered with 6 mhz crystal the lower model got a 10, i did'nt understood why a much better pic got a lower crystal. Now I got it 24mhz is nice for that card.

Merci beaucoup ;)