mdot_rtc_battery_backup

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  • March 20, 2017 at 10:27 am #17894
    Evangelos Almpanidis
    Participant

    Hello to everyone

    We are planning to use mdot as a lora class c device and use the internal RTC to log the timestamp of the measurements that are carried out. The device will have constant power and there is no need of a battery in order operate. In case of power failure though, we would like to have an external battery or ultracapacitor in order to keep the time running, so when the device power up again it will have the correct time. From my research i can see that the stm32f411RET has a VBAT pin for that purpose. Probably I am missing something but I can’t find any information on where this pin has been assigned in the mdot headers (if it has).

    Do we also need an external crystal for the internal RTC of the stm32f411 in case of power failure?

    Any link schematic or other source of information would be really helpful

    Thank you for your help in advance

    March 20, 2017 at 3:18 pm #17937
    Leon Lindenfelser
    Moderator

    Hi Evangelos,

    Sorry but the VBAT pin is not externally available on the mDot. It is tied directly to VDD.

    Kind regards,
    Leon

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