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TM4C123GH6PM: issue of HIBERNATE_WAKE_RTC

Susan Yang
Genius 9955 points
Part Number: TM4C123GH6PM

Dear team,

The customer used this chip to make a batch of battery-powered control boards. The circuit board only works for two hours a day, that is, from 7:00 to 9:00, and it stays dormant at other times.

The program will recalculate on 9:00 and set the next wake-up RTC number to ensure that the setting is successful every time .

By 7 o'clock the next day, under normal circumstances, the board can automatically wake up on time.

But after running the program, it is found that each board may not be able to wake up at the time. The board may be normal for a few days, and it may not wake up one day. Since the wake-up is not successful this time, the next wake-up count will not be updated, which will result in the subsequent failure to wake up forever. There have been problems with every board.

The chip version currently in use is G4, and the complete model is TM4C123GH6PMT7. Boards that fail to wake up can only be reset by powering off or through the wake pin.

Although the wake-up fails, the RTC count inside the chip is still going.

The following are the main functions which are used:


HibernateWakeSet(HIBERNATE_WAKE_RTC|HIBERNATE_WAKE_PIN);

HibernateCounterMode(HIBERNATE_COUNTER_RTC);

HibernateRTCMatchSet(0,time);

HibernateRequest();

The customer also find a similar description in the following doc

https://www.ti.com.cn/cn/lit/er/spmz849f/spmz849f.pdf?ts=1631233608035&ref_url=https%253A%252F%252Fwww.ti.com.cn%252Fproduct%252Fcn%252FTM4C123GH6PM%253FkeyMatch%253DTM4C123GH6PM%2526tisearch%253Dsearch-everything%2526usecase%253DGPN 

Please help to check this issue.

BR,

Susan

  • 0
    TI__Guru**** 191316 points

    Hi Susan,

    HIB#1 - Some Hibernation Module Registers may not Have the Correct Value in two Situations.

      I don't think the two situations apply to the problem description as the RTCEN and PINWEN are both set.

    HIB#2 - Reading the HIBRTCC and HIBRTCSS Registers may Provide Incorrect Values

      This errata may be something to look into further. Can customer take the workaround and try if it makes a difference?

    HIB#3 - Device Fails to Wake From Hibernation Within a Certain Time after Hibernation is Requested

      I don't think this one applies. For this errata to happen, the wake event has to happen with 32uS before nHIB signal is asserted until VDD drops below BOR or the POR falling edge. The customer's wake event is actually 7am the next day, it is way over 32uS. If you have in doubt, you can add the workaround too but I doubt this errata is applicable.

    HIB#4 - RTC Match Event is Missed if it Occurs in a Certain Window

      Again, this errata only happens if the match occurs with 92uS (3 RTC clocks) after the setting the HIBREQ bit. Customer's match value will be 7am the next day after setting HIBREQ. It is way over 92uS. It doesn't hurt to try the workaround if in doubt. 

    HIB#14 External Wake Interrupt may be Lost When Returning From Hibernation

      I believe the customer is using the RTC wake to wake up at 7am, correct? It is not that customer uses external nWAKE pin to wake up the device at 7am, right? So I don't think this errata applies. 

      Can you confirm if customer follows the TivaWare hibernate example, will it work?