Daniel wrote :

> Hi all,
> I am looking for code (or PIC programming help) for a clock with
> calendar and one channel controller.
>
> I am considering using a DS1307 RTC and 16F84 PIC or similar.
> It will be
> used outdoors, battery powered with no mains reference. The accuracy
> needs to be as accurate as possible but no more than ? 2 minutes per
> month.
>
> I have read that a RTC chip does not necessarily ensure
> better accuracy
> or stability. Should it all be done in the PIC?
>
> I need to switch at specific times on certain days, plus it needs
> compensation / adjustment for daylight saving times.
>
> I can find plenty of code examples for regular clocks but not
> with dates
> (calendar).
>
> Does anyone have any guidance for this?
>
> Thanks,
>

Hi.

The RTC help with some of the "calendar-calculating", and
I'd guess the RTC is more low-power that a running PIC.
The accuracy is depending on the timebase use in either case,
normaly a crystal. Less programming if you can use a RTC chip
that does all calculating and (maybe) the alarm function.

B.t.w, any special reason to use the old 16F84 ? There are
probably newer chips, check the nanoWatt variants.

Jan-Erik.

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