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Beware that this post is related to an SDK in maintenance mode
More Info: Consider nRF Connect SDK for new designs

Implementing time_t as 64 bit to solve Y2038 problem.

Arie_tondo

Hi,

We use SDK nRF5_sdk15.2 and ARM GCC cross compiler to develop application that runs on nRF52840.

We use new lib, as it was done in examples.

I noted recently that time_t is implemented as signed 32 bit what means that it can cause problem in 2038.

We use time_t to save epoch as we need to use c library functions (like mktime, ...)

Is there a way to change the definition of time_t to 64 bit or otherwise prevent the Y38 problem? 

  • 0

    Hi,

    Depending on what IDE and SDK you are using, time_t is implemented as different things. In Keil with nRF5 SDK time_t is implemented as an unsigned 32 bit int which will most likely be hit by the Y38 issue. As far as I can see typecasting this to a 64bit based type may cause code-compliancy issues with other functionalties depending on the time library. Since the nRF5 SDK is in maintenance mode, there are no guarantees that this will be fixed - for more details see this blog post.

    One option to avoid this issue is move from nRF5 SDK to nRF Connect SDK (NCS) and Visual Studio Code, where time_t is implemented as the 64 bit type long long.

    I've posted two images below from testing and verifying time_t type in NCS v1.9.1. 

    Type declaration of time_t in time.h:

     

    Output of example printing type declaration:

    Let me know if this answers your question, and if you need any pointers to how to get started with NCS

    Kind regards,
    Andreas

  • 0

    Hi,

    thank you for the reply.

    We have units in the field that can be updated only by FOTA(above cellular network), Is it possible to update in DFOTA units that runs SDK and soft device to units that run sdk connect and zephyr?

  • 0 in reply to Arie_tondo

    Hi,

    Unfortunally we do not support  DFU/FOTA upgrades from nRF5 SDK to nRF Connect SDK. This thread from a few months ago is a good read as to why we don't support it, some reasons to migrate from nRF5 SDK to nRF Connect SDK, as well as the challenges that may come with trying to create a custom DFU method.

    I believe the discussion in that thread answers this questions, and feel free to join in on that thread if you have any follow up questions to what is asked there. Additionally, please feel free to ask more questions here as well if your question is still unanswered! 

    Kind regards,
    Andreas

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