Multiple PICS from Same Crystal?


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  1. #1
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    Jan 2010
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    Default Multiple PICS from Same Crystal?

    Does any one know if it's possible to clock multiple PICs from the same external oscillator crystal?

    I have a project in mind that might need multiple synchronized chips.

    I've tried this project unsuccessfully on a single chip but there are too many pulses over too wide of range.

    This project would involve simulating a rotating shaft that has multiple encoders. The shaft rotates at variable speed between 0 and 2400 RPM.

    The rotating shaft has several encoder outputs:
    1) 1 per rev - pulse is high for 1/120 of a revolution.
    2) Flip Flop - high for one revolution, low for the next revolution.
    3) 3 per rev - each pulse is High for 1/120 of a revolution.
    4) 4 per rev - each pulse is High for 1/120 of a revolution.
    5) 5 per rev - each pulse is High for 1/120 of a revolution.
    6) 6 per rev - each pulse is High for 1/120 of a revolution.
    7) 60 per rev - each pulse is High for 1/120 of a revolution (square wave).
    8) 1024 per rev - square wave.

    All encoders (except 2) have a rising edge phase aligned with the rising edge of the one per rev encoder (1).

    The flip flop encoder (2) changes state on the rising edge of the one per rev encoder (1).

    With (3) through (6), only one of these is actually needed at any given time.

    Any ideas on synching multiple PICs would be greatly appreciated.

    Thanks,

    Bob W.
    Wozzy-2010

  2. #2
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    Wellton, U.S.A.
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    Never tried it, but it was talked about here
    http://www.picbasic.co.uk/forum/showthread.php?t=575
    Dave
    Always wear safety glasses while programming.

  3. #3
    Join Date
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    Thanks Dave,

    Not sure why my query missed that post.
    I'm about to pull this project back out of the bin and give it a go again.

    Bob
    Wozzy-2010

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