6 Mhz Oscillator


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  1. #1
    Join Date
    Apr 2010
    Posts
    12

    Default 6 Mhz Oscillator

    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

  2. #2
    Join Date
    May 2004
    Location
    NW France
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    Wink no mod needed ...

    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
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  3. #3
    Join Date
    Apr 2010
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    12


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    Default Great, it explains a lot.

    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

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