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Is CC254X RTC not accurate?

Hansome
Intellectual 660 points

CC254X RTC continues 12 hours, then it looses about 8 minutes.

Is its accuracy so poor? How can I improve the accuracy of CC254X RTC? Thanks!

  • 0
    TI__Mastermind 29650 points
    Hi Hansome,

    The sleep timer / RTC uses the 32kHz clock as its time base. It seems you have 11000ppm (1.1%) wrong 32kHz frequency compared to a correct 32768Hz clock.
    Most likely this is due to the internal 32kHz RC oscillator being used instead of the 32.768kHz sleep crystal. See chapter 4.4.3 in the user guide (www.ti.com/.../swru191d.pdf) for more details.

    .:svend
  • 0 in reply to svendbt
    TI__Guru** 106705 points
    It could also be due to incorrect load capacitors on the 32 kHz crystal.
  • 0 in reply to Fredrik K
    Intellectual 660 points

    Fredrik,

    I want to write a program to test the accuracy of the RTC, Any suggestion? Thanks!

    Hansome

  • 0 in reply to Hansome
    Guru 735685 points
    You can try to use those APIs in OSAL_ClockBLE.c.
  • 0 in reply to YiKai Chen
    Intellectual 660 points
    Fredrik,

    In rtc.h,
    typedef UTCTimeStruct rtc_datetime_t;
    void rtc_get(rtc_datetime_t* datetime);
    void rtc_set(rtc_datetime_t* datetime);

    In rtc.c,
    void rtc_get(rtc_datetime_t* datetime)
    {
    osal_ConvertUTCTime(datetime, osal_getClock());
    }

    void rtc_set(rtc_datetime_t* datetime)
    {
    osal_setClock(osal_ConvertUTCSecs(datetime));
    }

    When simpleProfile_ReadAttrCB,
    case SIMPLEPROFILE_CHAR6_UUID:
    *pLen = SIMPLEPROFILE_CHAR6_LEN;
    rtc_get((rtc_datetime_t*)pValue);
    //VOID osal_memcpy( pValue, pAttr->pValue, SIMPLEPROFILE_CHAR6_LEN );
    break;

    When simpleProfileChangeCB,
    case SIMPLEPROFILE_CHAR6:
    SimpleProfile_GetParameter(SIMPLEPROFILE_CHAR6, &datetime);
    rtc_set(&datetime);
    break;

    This is my codes about RTC, but the accuracy is bad. Is this usage of RTC correct? Thanks!

    Hansome