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[OMAP-L138 (Rev.E), RTC] The default value of Control Register (CTRL) is not 0

Naoki Kawada
Guru 19890 points

Hi,

My customer has a question about the default value of RTC CTRL register.
According to TRM ,the default value should be 0. And actually, they could see 0 on the most of devices in their factory.
But they found some devices had unexpected default value, such as 0x00000061 or 0x00000020.
Is this expected behavior ?

It seems that their software was relying on the default value, so some end products did not work correctly. Please note the workaround has been found -- resetting CTRL register with default value before configuring RTC. 

Best Regards,
Kawada

  • 0
    TI__Guru** 116100 points
    Hi Kawada,

    Due to this, customer is facing any issues on that boards (few) related to time ?
  • 0
    TI__Guru* 83715 points

    Kawada-san

    This is not expected behavior. Please make sure that the boards dont have any issues in-terms of providing stable RTC clock and voltage etc.

    Please also make sure that even though not directly related, the customer software is following the recommendations in the reset consideration section in the RTC chapter in the TRM and they are doing a software reset etc as part of configuration/initialization

    When the device is initially powered on, the RTC may issue spurious interrupt signals to the CPU.avoid issues, a software reset should be performed on the RTC module before the CPU interrupt controller is initialized. As the RTC is configured, the SPLITPOWER bit in the control register (CTRL) should be set. A software reset is performed on the RTC by setting the SWRESET bit in the oscillator register (OSC). The software reset applies to all registers except the oscillator (OSC) and kick (KICKnR) registers. The RTC requires three 32.768-kHz reference clocks to pass before RTC registers can be accessed.

  • 0 in reply to Mukul Bhatnagar
    Guru 19890 points
    Hi Mukul,

    Thanks for your reply. We are now confirming your suggestions.
    If we had any updates from the customer, I'll let you know.

    Thanks,
    kawada