About maximum year in DS1307

Forum 2005-2010 (read only) Software Syntax & Programs
1

Hi, I red that till 2100 DS1307 has an accurate calendar, but when I'm trying to write an year >49 with this code

int new_year = (first_year*10) + second_year;
RTC.set(DS1307_YR,new_year);

It doesn't write it to DS1307, why? But if the year is 2049 and the whole year elapsed it continues to 2050.

2

What values are in first_year and second_year? What are their types?

Since new_year is defined as an int, the multiplication and addition operations could cause an overflow, resulting in new_year being negative. Perhaps that is why the RTC won't accept it.

3

The values of first_year and second_year are between 0-9, both of them are from type int.

4

Is the value sent to the RTC to set the year supposed to be a two digit number (10) or a 4 digit number (2010)?

5

@Morpheous

I'm trying to write an year >49

Are you using the DS1307 library from here: Google Code Archive - Long-term storage for Google Code Project Hosting.? (See Footnote.)

If so, then maybe you can contact the author and ask why the following is in the DS1307::set() function in DS1307.cpp

 case DS1307_YR:
    if(v<50 && v>-1)
    {
      rtc_bcd[DS1307_YR]=((v / 10)<<4) + (v % 10);
    }
    break;

I mean, why the heck would he have that v < 50 in there ?

Alternatively, maybe you can find another library that actually makes sense.

Regards,

Dave

Footnote:
If you are not using that library, how about telling us what you are using?

6

Yea, as I se[ch1077], the problem is in the library not in the code or the IC. I suppose that if I change the value v<50 it could work?

P.S. I tried to modify the .cpp file and it works now. Thanks for the HELP !!!