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MSP430FR5043: USS XTAL settling time

CY H
Intellectual 400 points
Part Number: MSP430FR5043

Hi,

I'm currently using a MSP430FR5043 custom board with USS library.

And I found out that the USS XTAL is turned on and off in every measurement. So I have to wait the XTAL to settle every time. Can I set the USS XTAL to always-on to bypass the waiting ?

  • 0
    TI__Expert 7015 points

    If you are using the code examples of EVM430-FR6043, it is not recommended to manually control the USS XTAL. The USSXTAL is automatically controlled by the code example. 

    The startup time for the USSXTAL is maximum 1.9ms for crystal resonator and 0.12ms for ceramic resonator (8MHz). Normally the USS measurement is 1Hz. So it should be no problem to power off the USSXTAL between the two measurements. It will save the power consumption for the system. If set the USSXTAL always-on, the power consumption will be bigger. 

    Thanks, 

    Lixin 

  • 0 in reply to Lixin Chen1
    Intellectual 400 points

    Hi Lixin,

    Thank you for replying. The power consumption does not concern me in this project. I would like to boost the measurement frequency to more than 80Hz, so the startup time is really a big issue to me. If there is any method that can bypass the XTAL startup process, please let me know. Thank you.

    Best regards,

    CY H

  • 0 in reply to CY H
    TI__Expert 7015 points

    What application are you using FR6043? The USS calculation will take long time after ADC sampling. The resonator wake-up time is not critical 1.9ms in the time path. The maximum frequency of the USS sampling is 20Hz for gas detection and 40Hz for water detection. 

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