Investigate leap year bug

[cbonsig]

By the way, have you fixed the "leap year" bug in your code?
See if you can set the date to Feb. 29, 2016. That will be a Monday, by the way.

(via Robert on Tumblr site)

[Robert-L]

  case STATE_DATE_DAY:
    // upper right digit region: increment day
    if (tapZone == TAP_MINUTEPLUS){
      if (newMonth == 4 || newMonth == 6 || newMonth == 9 || newMonth == 11){
        if (newDay < 30) newDay++;
        else newDay = 1;
      }
      else if (newMonth == 2){
        if (newDay < 28) newDay++;  // See this line.
        else newDay = 1;
      }
      else{
        if (newDay < 31) newDay++;
        else newDay = 1;
      }
      newDisplayState = STATE_DATE_DAY;
    }

    // lower right digit region: decrement day
    else if (tapZone == TAP_MINUTEMINUS){
      if (newMonth == 4 || newMonth == 6 || newMonth == 9 || newMonth == 11){
        if (newDay > 1) newDay--;
        else newDay = 30;
      }
      else if (newMonth == 2){
        if (newDay > 1) newDay--;
        else newDay = 28; // See this line, too.
      }
      else{
        if (newDay > 1) newDay--;
        else newDay = 31;
      }
      newDisplayState = STATE_DATE_DAY;
    }

My (somewhat ugly) fix is:

  case STATE_DATE_DAY:
    // upper right digit region: increment day
    if (tapZone == TAP_MINUTEPLUS){
      if (newMonth == 4 || newMonth == 6 || newMonth == 9 || newMonth == 11){
        if (newDay < 30) newDay++;
        else newDay = 1;
      }
      else if (newMonth == 2){
        if (newDay < ((year % 4) == 0 ? 29 : 28)) newDay++;  // ugly but I expect it will work through A.D. 2099
        else newDay = 1;
      }
      else{
        if (newDay < 31) newDay++;
        else newDay = 1;
      }
      newDisplayState = STATE_DATE_DAY;
    }

    // lower right digit region: decrement day
    else if (tapZone == TAP_MINUTEMINUS){
      if (newMonth == 4 || newMonth == 6 || newMonth == 9 || newMonth == 11){
        if (newDay > 1) newDay--;
        else newDay = 30;
      }
      else if (newMonth == 2){
        if (newDay > 1) newDay--;
        else newDay = ((year % 4) == 0 ? 29 : 28); // again, ugly but I expect it will work through A.D. 2099
      }
      else{
        if (newDay > 1) newDay--;
        else newDay = 31;
      }
      newDisplayState = STATE_DATE_DAY;
    }

NOTE: year 2100 is divisible by 4 but is not a leap year. This won't bother you, though, will it?
Possibly related: what happens when you try to set the year to a value greater than 2099?

[cbonsig]

Excellent, thanks!! I will give this a try next time I tinker with the code. I've been in hardware mode for the last few weeks leading up to Maker Faire, so I haven't touched the code at all in a few weeks. I am using the Chronodot 2.1, so the Arduino time is served by the Chronodot -- The specs for the DS3231 state that it accurately manages leap years through 2100. By then, I trust that my grandchildren will have found a solution.

http://datasheets.maximintegrated.com/en/ds/DS3231.pdf

[Robert-L]

No, I mean you do have a leap year bug.

Try setting the date to Feb. 29, 2016. Can you?

(I was trying to let you know about this before Maker Faire. Oh well.)