Sure. Just start up a timer interrupt to accumulate time
and NEVER turn off the micro. Add a supercap or small battery to
provide for battery change outs.

Lots of discussion on this list last year on how to get an accurate
timebase using error accumulator overflows.

Some PICs (16F87x)also support the use of a 32kHz crystal on certain
timer pins. You still have to keep the micro running, but your
timekeeping code becomes simpler.

Been there, done that, and found that a RTC chip like the DS1302
just makes a LOT more sense, if you can pursue that option. 3 pins (2 of
which you can share with other functions if you're clever) and a
energy source (MnO, Li or supercap) gets you a hassle free solution.

John Waters wrote:
>
> Hi All,
>
> Can I use a microcontroller alone without any calendar chip to keep track of
> the date? I want that my device should be able to set up its clock from a PC
> through the COM once and it will know the DD/MM/YY HH/MM/SS at any time, is
> it possible?
>
> Thanks in advance!
>
> John

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads