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CCS/MSP430FR5992: Invalid time value in RTC_C module

Paulina Bednarczyk
Intellectual 320 points
Part Number: MSP430FR5992

Tool/software: Code Composer Studio

Hi, 

I've a problem with RTC_C module. 

My board does not have an external oscillator. I need to run RTC with only internal oscillators available.
I launched ACLK from the VLO source and MCLK from the DCO source. Unfortunately, the time entered in the time registers does not change.

Which clocks should I run and from which sources to get full functionality without an external oscillator?

Best regards, 

Paulina

  • 0
    TI__Expert 6635 points

    Hi Paulina,

    The RTC_C module must be run with an external 32kHz crystal:

    Unfortunately, I do not see a way to utilize the RTC module without it.

    Thanks,

    Mitch

  • 0 in reply to Mitch Ridgeway
    Intellectual 320 points

    I found an information that the processor has a built-in 32khz clock.

    "The clock system includes support for a 32-kHz watch-crystal oscillator XT1 (LF)..."

    and

    "The LFXT oscillator supports ultra-low-current consumption using a 32768-Hz watch crystal. A watch
    crystal connects to LFXIN and LFXOUT and requires external capacitors on both terminals."

    And it's my question. Processor has build-in oscillator and external capacitors (in using only processor, not launchpad).

    Best regards, 

    Paulina

  • 0 in reply to Paulina Bednarczyk
    TI__Expert 6635 points

    Hi Paulina,

    The information you are citing is talking about external crystals. 

    Paulina Bednarczyk said:
    "The clock system includes support for a 32-kHz watch-crystal oscillator XT1 (LF)...

    could actually read:

    "The clock system includes support for an external 32-kHz watch-crystal oscillator XT1 (LF)..."

    Paulina Bednarczyk said:
    "The LFXT oscillator supports ultra-low-current consumption using a 32768-Hz watch crystal. A watch
    crystal connects to LFXIN and LFXOUT and requires external capacitors on both terminals."

    This means that the an external watch crystal will connect to the LFXIN and LFXOUT pins. 

    The FR5992 device does have an internal VLO clock (with typical frequency of 10kHz), but there is not an internal 32kHz clock that can be used for the RTC module.

    Hope this clarifies things a bit.

    Thanks!

    -Mitch

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