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powermac1
Visitor II
January 16, 2007
Question

AR Timer as 25ms Timebase

  • January 16, 2007
  • 2 replies
  • 739 views
Posted on January 16, 2007 at 07:11

AR Timer as 25ms Timebase

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    2 replies

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    powermac1Author
    Visitor II
    January 5, 2007
    Posted on January 05, 2007 at 06:41

    Hello Folks,

    i programmed the ART as freerunning Timer.

    Fosc= 3,6864 MHz, ClkDiv= 3, Prescl= 128

    Fin= 9600, RC= 10h

    If my Calculations are correct, the above Settings = 25ms.

    The Overflow Interrupt is used to update some Calcs(Tcyc.

    As far as i know, ARTs need no additional cycles for INT and Reload.

    They run and run until RESET. OK, the INTMASK must be written but

    it have no effect on the running Timer. Hey, its Hardware.

    Is it the same with the ST6265 ART. Or are there add. Cycles?

    best regards

    Andreas

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    powermac1Author
    Visitor II
    January 16, 2007
    Posted on January 16, 2007 at 07:11

    Hi again,

    there are ''dead'' cycles when using the ART as INT source.

    To check this out, i programmed a simple software RTC using the

    ART OverflowINT as Timebase.

    Every INT increments a register til 40d. 25ms*40=1s.

    result: the clock runs ahead.

    question: WHY?

    Andreas

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