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MSP430FR6047: Ceramic resonator clock accuracy

Chris Kang2
Prodigy 80 points
Part Number: MSP430FR6047
Other Parts Discussed in Thread: EVM430-FR6047

Hi,

We are testing the USS water reading accuracy with our product which has been designed based on the EVM430-FR6047.

As TI recommended, we are using a 8Mhz ceramic resonator for USS reading and a 32.768KHz crystal for sleep mode.

Recently we've seen a water reading accuracy issue.

From the analysis activities, we want to check the stability and accuracy of ceramic resonator in the design.

We are using the same resonator in the dev board -  Abracon, AWSCR-8.00CV-T.

Here are some questions.

- Could you explain the expected accuracy performance over temperature ranges?

- The eval board has a 8Mhz crystal. Can we use the clock course for the USS function? If so, which code do we need to change?

- Can we replace the ceramic resonator with TCXO? If so, which code do we need to change?

Thanks,

Chris

  • 0
    Prodigy 80 points

    Here is the schematic for the clock sources.

  • 0 in reply to Chris Kang2
    TI__Mastermind 28516 points

    Hi Chris,

    Actaully, the accuracy of resonatior is enough for water meter. If you would like to use crystal(keep a high accuracy in whole temp range), you need to increase the USS XTAL Setting Count(us)(Can try to change to 4000)

    Thanks!

    Best Regards

    Johnson

  • 0
    Prodigy 80 points

    Hi Johnson,

    Thank you for the information.

    Could you explain how the accuracy of resonator is enough for water meter? Did you mean by cross wide temperature range, 33F to 185F?

    For the DC setting for crystal, is that value the waiting time for crystal to get stabilized?

    Is there any F/W setting change required? As selecting crystal or resonator?

  • 0 in reply to Chris Kang2
    TI__Mastermind 28516 points

    Hi Chris,

    The resonator/crystal is used to HSPLL, and we have a code to check if this accuracy is noraml. If you don't get the Error, this is OK.

    For Low/High temperature, crystal have a more high performance than resonator. But for Water meter, the worn temperature is OK, thus lots of customer will use resonator in water meter, and use crystal in gas meter. 

    Yes, this Parameter of "USS XTAL Setting Count(us)" is waiting time for crystal.

    Thanks!

    Best Regards

    Johnson

  • 0 in reply to Johnson He
    Prodigy 80 points

    Hi Johnson,

    This is really helpful. Could you point out the code location to check the clock accuracy? What is the failure condition?

    Thanks,

  • 0 in reply to Chris Kang2
    TI__Mastermind 28516 points

    Hi Chris,

    ERROR Code:

    If you have been installed the USS design Center , you can find all Error Handling in GUI-> Help-> User's Guide.

    Thanks!

    Best Regards

    Johnson

  • 0
    Prodigy 80 points

    Hi Johnson,

    For the USS XTAL Setting Count with 4000, do I need to change the UPS and DNS gap value too(maybe 7000)? Does the driver automatically increase the gap time?

  • 0 in reply to Chris Kang2
    TI__Mastermind 28516 points

    Hi Chris,

    This parameter don't affect other parameter(gap timer).

    Thanks!

    Best Regards

    Johnson

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