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tj2
Visitor II
March 27, 2008
Question

Cannot exit StandbyMode on RTC alarm

  • March 27, 2008
  • 14 replies
  • 2121 views
Posted on March 27, 2008 at 06:41

Cannot exit StandbyMode on RTC alarm

    This topic has been closed for replies.

    14 replies

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    tj2Author
    Visitor II
    October 24, 2005
    Posted on October 24, 2005 at 07:21

    Hi.

    I cannot get our target board to wakeup from the RTC alarm. The code is working on the MB393B demoboard. So I think it's hardware related. But I cannot determine where the problem could be. I've verified the 32KHz clock and it is running...

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    ben2
    Visitor II
    October 24, 2005
    Posted on October 24, 2005 at 07:29

    is you main oscillator running ? To exit from any mode apart from wfi and lpwfi the main oscillator must be running

    T
    tj2Author
    Visitor II
    October 24, 2005
    Posted on October 24, 2005 at 07:30

    Yes, the main oscillator is running.

    T
    tj2Author
    Visitor II
    October 24, 2005
    Posted on October 24, 2005 at 10:58

    On the MB393B board J3 is fitted.

    On our board a 1µF ceramic capacitor is connected between V18BKP (pin 55) and VSSBKP. VSSBKP is connected to GND. And there is not an external power source is connected to the V18BKP pin.

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    tj2Author
    Visitor II
    October 25, 2005
    Posted on October 25, 2005 at 07:41

    I've measured the voltage on the V18BPK pin and it was only 1.56V. Is this voltage too low for the RTC to operate?

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    tj2Author
    Visitor II
    October 25, 2005
    Posted on October 25, 2005 at 07:56

    The voltage on the V18pin is 1.85V when not in standby, and drops to the 1.56V when entering standby mode.

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    tj2Author
    Visitor II
    October 25, 2005
    Posted on October 25, 2005 at 09:12

    The Standby pin does not go high. There is a 100k pull-up connected to the pin.

    When using the wake up pin the wake-up function correctly.

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    tj2Author
    Visitor II
    October 25, 2005
    Posted on October 25, 2005 at 09:19

    I've just changed PCU_LPMEnter ( PCU_STANDBY ); to PCU_LPMEnter ( PCU_STOP );

    And here the RTC wake up function correctly. So it is somehow related to the standby mode.....

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    tj2Author
    Visitor II
    October 25, 2005
    Posted on October 25, 2005 at 10:55

    I made another test:

    I thought maybe the 32KHz crystal didnt function during standby mode, so I made a program where the RTC_CounterValue() is send to the PC trough the UART. And the result is that the RTC _is_ running during standby. So I cannot understand why the alarm function wont work.

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    tj2Author
    Visitor II
    October 25, 2005
    Posted on October 25, 2005 at 11:58

    The example is working on the MB393B demo board.

    But not on our board. - The CPU never wakes up again and a reset or a logic high on the wake up pin is necessary.

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