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Re: Digest Number 24

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  • Jens Hildebrandt
    Hi Kevin, thank you very much for your help. Based on the information you gave me I managed to trim the clock frequencies close enough to each other to be
    Message 1 of 2 , Dec 17, 2000
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      Hi Kevin,

      thank you very much for your help. Based on the information you gave
      me I managed to trim the clock frequencies close enough to each other
      to be acceptable.

      Jens

      --- In acex-users@egroups.com, kevin.hansen@f... wrote:
      >
      > Jens,
      > It will be very difficult to get two ACE1202 microcontrollers to be
      exactly
      > the same frequency when using the internal oscillator.
      > The accuracy on the internal oscillator is +/-10%.
      > If you must have the same frequency you must use the External Osc
      mode with
      > a crystal or resonator.
      > This should give you better than +/-0.5% accuracy.
      >
      > Now with that said I will answer your questions about how the
      oscillator
      > frequency is adjusted.
      >
      > How do values written to 0xBC affect the oscillator?
      > The recommended values written to 0xBC are F0 thru FF.
      > Values below F0 become very fast and are non linear.
      > The typical value written to get 2mhz is FA.
      > A value of F0 will give about 3.3mhz.
      > A value of FF will give about 1.1mhz.
      >
      > How much does clock speed change when I increase/decrease the
      register
      > contents by one?
      > Each step is aboout 50-100khz.
      >
      > Which values must Bit CTRL0 and CTRL1 have when programming register
      0xBC?
      > 0xBC is programmed just like Initialization register 1.
      > CNTRL1=1 CNTRL0=0
      >
      > Regards,
      > Kevin Hansen
      > Fairchild Semiconductor
      >
      >
      >
      >
      >
      > acex-users@egroups.com
      > 12/06/2000 01:12 AM
      >
      >
      > Please respond to acex-users@egroups.com
      >
      > To: acex-users@egroups.com
      > cc:
      > Subject: [acex-users] Digest Number 24
      >
      >
      >
      > There is 1 message in this issue.
      >
      > Topics in this digest:
      >
      > 1. ACE clock trimming
      > From: "Jens Hildebrandt" <hil@e...>
      >
      >
      >
      ______________________________________________________________________
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      >
      ______________________________________________________________________
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      >
      > Message: 1
      > Date: Tue, 05 Dec 2000 15:02:04 -0000
      > From: "Jens Hildebrandt" <hil@e...>
      > Subject: ACE clock trimming
      >
      > Hi,
      >
      > I use two ACE1202 running identical code to generate stepper motor
      > patterns. I tell the ACEs by command how many steps to go and with
      > which step period. When I start both motors simultaneously and let
      > them go a larger number of steps I notice that one motor finishes
      it's
      > number of steps earlier than the other. The more steps to go the
      > bigger the difference grows. Seems that there is a difference in
      clock
      > speed between the two controllers. Hence, I will have to adjust the
      > on-chip oscillator frequency of one of them to the other one's but I
      > don't know about how to do this beside that I have to write
      something
      > to register 0xBC.
      > I know this question has been around here some times ago but I
      didn't
      > see an answer to it so I ask it again. How do values written to 0xBC
      > affect the oscillator? How much does clock speed change when I
      > increase/decrease the register contents by one? And finally, which
      > values must Bit CTRL0 and CTRL1 have when programming register 0xBC?
      > Anyone out there willing to share his knowledge with me?
      >
      > TIA
      > Jens
      >
      >
      >
      >
      >
      ______________________________________________________________________
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      >
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