Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

  • State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 30 subscribers
  • Views 241 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

MSP432E401Y: synchronize RTC with GPS in sub-second resolution

John Qin
Prodigy 40 points
Part Number: MSP432E401Y

We interfaced the MSP432E401Y with a GPS module. We need to periodically synchronize the RTC clock with GPS (with GPS PPS interrupts) down to millisecond resolution. We configured RTC to RTC CALENDAR mode. Based on  Peripheral Driver Library User's Guide, we can use HibernateRTCSSGet() to get sub-second counter values and HibernateCalendarSet(&rtcnow)  to set the time down to second resolution. We wish to reset the sub-second counter value to 0, but we did not find any API from the Peripheral Driver Library User's Guide to do that. My question is:

1) Does the sub-second counter drives the RTC Calendar seconds counter, or they are synchronized?

2) How can I reset the sub-second counter value?

Thanks

  • 0
    TI__Mastermind 28525 points

    Hello John,

    Section 6.3.5 of the MSP432E4 TRM describes the RTC behaviour.  Section 6.3.5.1 paragraph 3 states that the HIBRTCC (RTC Counter register) is set by writing the Hibernation RTC Load register, and that any write to this register, clears the subsecond counter field.  So, it does appear that updating the time will clear the subsecond counter. 

    But in Paragraph 2, it is mentions that when using Calendar mode, the Sub Second counter register can not be used.   It doesn't elaborate, but it seems to apply that in Calendar mode, 1 second is the finest resolution. 

    Thanks,

    JD

       

  • 0 in reply to JD Crutchfield
    Prodigy 40 points

    Hi JD,

    I tested and confirmed the statement in Paragraph 2, in Calendar mode the Sub Second counter register can not be used. I came out with a walkaround: to reset the RTC all together, then the Sub Second counter restarted from 0.