[Icc-avr] RTC - how to compute the difference in minutes

[Paul Mateer]

Maybe if you convert the date to Julian Days that would help.  If
possible maybe the RTC could trigger an interrupt to so you could
count days since event#1.  I built a "TAB" timer not to long ago, but
did the date compare as yy.mm.dd

	 TEST_RTC_TIME = (fix_hr * 100) + fix_min;
	 TEST_RTC_DATE = ((unsigned long)fix_rtc_yr * 10000)+((unsigned
long)fix_rtc_month *100)+(unsigned long)fix_rtc_date;


On Nov 14, 2007 11:42 PM, Robert Rademacher <robertrade at yahoo.com> wrote:
> Hi all,
>
> I'm wondering if anyone has done the difftime routine for ICCAVR that would
> compute the difference in minutes, using PCF8563 RTC. I know ICCAVR does not
> have time.h library.
>
> Here is the elapsed minutes calculation:
>
> To compute for elapsed minutes (format: dd.mm.yy  hh.mm)
>
> Start date-time: 14.11.2007 10.15
> Final date-time 15.11.2007 8.15
>
> Calculated for elapsed time: 22 hours or 1,320 minutes.
>
> This may look easy, but remember, we are dealing with leap year, specific
> number of days/month, etc that need to be factored in when calculating the
> difference between the start and end time-date stamps. It would be nice if
> there is a RTC IC that has the mktime/gmtime I can read off instead of
> individual numbers from date/time sections.
>
> I search everywhere for the code snippet designed for AVR and did not find
> what I'm looking for as described above.
>
> Any good suggestions, as I'm bit pressed for deadline. I am sure everyone
> may be interested in this potential solution.
>
> Robert
>
>
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-- 
Paul Mateer, AA9GG
Elan Engineering Corp.
www.elanengr.com