Working clock example using 32K watch crystal

[Darrel Taylor]

There's a couple good examples. I like Bruce's.
But it uses in-line assembly language instead of straight PBP.

The Elapsed Timer modification is nice too ... but ...

Nobody wins the LCD's.

[pedja089]

I was playing with TimC RTC code, and I found 1 problem...
If the interrupt occurs between these lines

      GoSub get_time      ' Update minutes and seconds
      TOGGLE LED_0
      LCDOut $fe,2,"Time: ",DEC hours, ":", DEC2 minutes, ":", DEC2 seconds, "   "

There is a chance to show 60 seconds.
It happened to me, so I then wondered what was going on...
Solution:

seconds        VAR BYTE bankA  ' variables within myint must be in bank 0.
minutes        VAR Byte bankA       ' Elapsed minutes
hours          var byte bankA
:
:
:
@myint                  ; create myint label
   TMR1H.7=1
    seconds = seconds+1  ' Increment second
    if seconds > 59 then
        seconds = seconds - 60    ' better then making seconds=0
        minutes = minutes + 1
        if minutes > 59 then
            minutes = 0
            hours = hours + 1
            if hours > 12 then hours = 1    ' simple 12 hour clock format
        endif
    endif 
 PIR1.0=0             ' Clear TMR1 int flag
   @ retfie  FAST

And remove get_time procedure

[pedja089]

I'm trying to add the calendar.
Does anyone have an idea how to make a calculation of leap year.
I tried this
If day>30+month.0 or (Month=2 and day>28 and year//4<>0) or (Month=2 and day>29 and year//4=0)then
month=month+1
but the code is 300b larger then this
If day>30+month.0 or (Month=2 and day>28)then
month=month+1
Is there a more efficient way?

[Ioannis]

How about using 3 If-Then's insead of one with 3 OR's?

Ioannis

[pedja089]

I spent all night trying to find the best way ... I think this is

              If month=2 then
                 If year//4<>0 then
                    DMonth=29
                 else
                    DMonth=28
                 endif
              else
              Dmonth=30+month.0 
              endif   
              If day>Dmonth then
@                CLRF _Day
@                INCF _Month,F
                 If month>12 then

And everywhere there is any = 0, I replaced the @ clrf, +1 replaced with @ incf.
The end result was the RTC which consumes about 2uA and code size about 500B.

[Ioannis]

I think you have to change the <>0 to =0 when you test for the modulo 4.

A better solution to cover more years (you code will not cover year 2100) is to use mod 400, mod 100 and mod 4 to test for leap year (mod 100 is NOT leap year, while 400 and 4 ARE leap years).

Of course we may not live in year 2100, but just in case...

Now about the @ commands, just be sure you are on page 0. Else you have to check the page bits. Or put this subroutine on top of your code.

Ioannis

[pedja089]

Thanks for that... It was just typo... 0-99 year is fine for this aplication.
On the top of ISR I have BSR=0, and isr routine is on top of my programm.