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MSP430F6779A: Detailed documentation on RTCLOCK

Part Number: MSP430F6779A

Hello,

When using RTCLOCK = 1, it is necessary to set RTCLOCK = 0 Strictly, only when turning on / off the RTCHOLD of the RTCCTL register? Or is RTCLOCK = 0 required for all other internal RTC registers?

The customer accesses the internal RTC register during operation by enabling / disabling the RTC interrupt in addition to the clock. They are concerned that the RTCLOCK needs to be released each time.

As for RTCLOCK, there is almost no explanation in the user guide, and there are only technical documents slaa666.pdf and sample programs, and the content is only about RTCHOLD.

How should RTCLOCK be used as an MSP430 specification? In addition, information such as how RTCLOCK behaves for RTC registers etc. is lacking.

Please provide accurate and organized information about RTCLOCK.

Best regards,

DDdoor

  • Hi,

    I haven't find any relationship between RTCLOCK  and RTCHOLD. You should unlock the RTC modue by write the passward before write to any registers of RTC.

    The detailed description about RTCLOCK could be found in the chapter3 of slaa666a.pdf which you mentioned. I will feedback to our development team to update the User's Guide which concerned you.

  • Please tell me about the contents of sla666.

    >One thing to note is that if RTCLOCK is set, the configuration of the bits locked by RTCLOCK may be held but not the bits themselves.

    I don't understand the above. Could you explain a little more? What do the following 1 and 2 specifically refer to?

    1、the configuration of the bits locked by RTCLOCK
    2、not the bits themselves

    >RTCLOCK may need to even be reset before reinitialization of some RTC registers such as the RTC time and date registers.

    Please tell me all the registers that need to release RTCLOCK.

  • Hello Wei.Jetim Zhao,

    How about after that?

    I think it will take time to complete the document,
    Would you please give me the information first?

    Best regards,
    DDdoor

  • Hi DDdoor,

    Sorry for late reply.

    Please find my comments:

    I don't understand the above. Could you explain a little more? What do the following 1 and 2 specifically refer to?

    [Wei] the reason why we have RTCLOCK bit is that the registers would be reset after an LPMx.5 cycle because the power of perihperal would be lost under LPMx.5 mode and the registers you configured previously will be reset after wake up from LPMx.5. So we need RTCLOCK to hold the registers value you configrued for RTC when device runs into LPMx.5. You may see some different register value from IDE, such as CCS in debug mode, but actually the register value should be the ones you configured after your device wake up from LPMx.5. And, the device won't go into a real LPMx.5 mode when you debug it with IDE such as CCS.

    >RTCLOCK may need to even be reset before reinitialization of some RTC registers such as the RTC time and date registers.

    Please tell me all the registers that need to release RTCLOCK.

    [Wei] This tells you that if you want to reinitialze the RTC registers, you need to reset the RTCLOCK bit firstly. Otherwise, the registers may be recovered by the held values after your reinitialization. That means for all the RTC registers I think.

  • Hello Wei.Jetim Zhao,

    Thank you for your reply.

    Should LPM3.5 retention logic be considered a copy of the RTC_C register that has been written as retain in the user guide table among the RTC_C registers?
    Is the following understanding correct?
    If RTCLOCK = 1, writing to RTC_C will not be reflected in LPM3.5 retention logic. However, access from the user to the RTC_C register is reflected.

    Best regards,
    DDdoor

  • Hi DDdoor,

    I would agree with you.

  • Hello Wei.Jetim Zhao

    Thanks for your help, I knew my understanding was correct, so I explained it to the customer.

    Thank you very much.

    Best regards,

    DDdoor

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