>Phillip Vogel <phillip@BARTAL.COM> said:

> Effect Ulit wrote:
>
> > thanks for the reply Dan.
> >  the thing is, Im putting the pic into sleep mode to save power, it will
be
> > running on a 3v button cell,  As you can imagine an external real time
clock
> > would defeat the pupose of the pic going to sleep.
> >  I need it to be on standby for many days. I cant see how any other chip
> > could be running from this same cell for any long period.
>
>
> Umm, Without going and leafing through data books, my Timex watch has been
> doing fine on a button cell for more than two years. I've seen PC real time
> clocks run on a single 3V cell for years.
>
> How much power are you trying to save? How accurate do you need your clock?
> You really do need to answer those questions with some degree of precision
in
> order to get a good solution to your design problem.
> p.
> --
> Phillip M. Vogel, President   | "It's not what you've been taught,
> Bartal Design Group, Inc.     |  it's what you've learned." (me)
> 318 Marlboro Road             | +1-201-567-1343 FAX:+1-201-568-2891
> Englewood, NJ 07631  USA      | phillip@bartal.com
>
> --

  Good questions you ask Phillip,
   no extra external components are necacary if I can mearly find out what
the wake up delay is with an acuracy of ~100ns  (or ~100 clk cycles), unless
this delay can vary greatly dependent on temperature and voltage or other
variables, this is all I need to compensate for. Another reason I dont want
to include another chip is that Im trying to make this circuit as physically
compact and simple as possible.

Dean

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