On Sat, 24 May 2003, Olin Lathrop wrote:

> Use a 32KHz watch crystal to run the timer 1 oscillator all the time.
> This will be the accurate time base.  Then you can use one of the newer
> PICs with on the fly oscillator switching to switch into high gear only
> when computation is required.  The exact instruction frequency won't
> matter since it won't be used to measure time.

Or even better:  Use Timer1 like Olin says, but use the internal 4MHz
oscillator, put the PIC to sleep and have Timer1 wake it up once in a
while.  A PIC12F629 will consume only about 4-5uA with T1 running and a
2-3V supply, I have measured mine at .005uA without T1.  Spec sheet will
tell you Ipd for all the peripherals.  I don't know if the 12F629 will
have enough memory and I/O pins for you, but if not the 16F628A looks even
better.

Dale
--
It's a thankless job, but I've got a lot of Karma to burn off.

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