RTC clock resets to 1969 even with VBAT connected

  • Hi ,

    I'm using ArmStoneA9r2 Dual board with the Linux Buildroot fsimx6B2020.04. For the managing the system clock, I've connected a CR2032 3.3V battery for RTC at the power connector.
    I'm using the command hwclock -w to set the time to RTC.

    After disconnecting the power abruptly, the system clock is getting rest to 1969 occasionally. This reset of time is causing a problem for the application we run which depends hugely on local time.

    Please help me with this issue.

  • Hi


    What exactly do you mean by "occasionally"?

    Could you describe a exact way to reproduce this issue?

    Power interruption to the device completely turns off the device. Even though power interruption is a regular thing, date and time is retained.
    Recently we had a building wide power interruption after which date and time got reset to 1969. Checked the voltage on the VBAT pins, it was still showing the 3v3 of battery.


    Does it also occur when use a 3v3 power adapter instead of a battery?

    I haven't tried connecting the power adaptor.

  • You have to measure the battery voltage while the system is shut off. Only then the battery is actually under load and then the voltage may drop.

    Your F&S Support Team

    F&S Elektronik Systeme GmbH
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