TM4C1294NCPDT: RTC capabilities in calendar mode of HibernateModule

I did not choose to start from 1900, that's how the function "HibernateCalendarGet" return the "struct tm" using TivaWare. But if you take a look on the tm4c1294 datasheet the RTC module doesn't seem to be restrict to start on 1900. That's why I got confused and could not reach a conclusion on which is the constrain of time range on the internal RTC.

Hi Charles,
Yes, you are right.
Just one last question: which files/functions should I modify so I can start count the years on 2000 rather than 1900? I'm assuming I shouldn't mess with the "time.h". I was wondering if I could just assume the "struct tm" provided on TivaWare function is starting from 2000 but then I realized doing this would probably mess with the mktime and localtime functions that I rely to convert from "struct tm" to "seconds since".

I'm already adding and subtracting 70 years to make a compatible "linux epoch" timestamp.

Another though is that moving the reference year around shouldn't mess with the leap year calculation as long the base year change is divisible by 4, is that correct?

Hi,

 I wonder if you have a chance to run the TivaWare hibernate example under <TivaWare_Installation>/examples/boards/EK-TM4C1294XL/hibernate. If you run this example, it shows how you can set the DD/MM/YYYY via the terminal window using the date command. When the proper the DD/MM/YYYY is entered it will call the DateTimeSet() function which will then load the sTime structure with the entered day/month/year and then call the HibernateCalendarSet() API.  See below.

In hibernate_command.c 

/*****************************************************************************
//
// Command: date
//
// Set the current system date.  Use format "DD/MM/YYYY"
//
//*****************************************************************************
int
CMD_date(int argc, char **argv)
{
    const char *pcNext;

    //
    // Check the argument count and return errors for too many or too few.
    //
    if(argc == 1)
    {
        return(CMDLINE_TOO_FEW_ARGS);
    }
    if(argc > 2)
    {
        return(CMDLINE_TOO_MANY_ARGS);
    }

    //
    // Convert the date to unsigned long
    //
    g_ui32DayIdx = ustrtoul(argv[1], &pcNext, 10);
    g_ui32MonthIdx = ustrtoul(pcNext+1, &pcNext, 10) - 1;
    g_ui32YearIdx = (ustrtoul(pcNext+1, NULL, 10) - 2000);

    //
    // Perform the conversions to a time struct and store in the hibernate
    // module after doing a minimal amount of validation.
    //
    if((g_ui32DayIdx > 31) || (g_ui32MonthIdx > 11))
    {
        return(CMDLINE_INVALID_ARG);
    }

    DateTimeSet();

    return(0);
}

In hibernate.c file.

//*****************************************************************************
//
// This function writes the requested date and time to the calendar logic of
// hibernation module.
//
//*****************************************************************************
void
DateTimeSet(void)
{
    struct tm sTime;

    //
    // Get the latest date and time.  This is done here so that unchanged
    // parts of date and time can be written back as is.
    //
    HibernateCalendarGet(&sTime);

    //
    // Set the date and time values that are to be updated.
    //
    sTime.tm_hour = g_ui32HourIdx;
    sTime.tm_min = g_ui32MinIdx;
    sTime.tm_mon = g_ui32MonthIdx;
    sTime.tm_mday = g_ui32DayIdx;
    sTime.tm_year = 100 + g_ui32YearIdx;

    //
    // Update the calendar logic of hibernation module with the requested data.
    //
    HibernateCalendarSet(&sTime);