> A question crosses my mind - what would use least power:
>
> 1. Running a PIC at a high clock speed for short bursts and sleeping in
> between; or
> 2. Running at a slow speed almost constantly (no time left for
> sleeping)?

The latter if clock rate is just enough to do the job.  This is because it
takes time and therefore wasted current to start up the main oscillator,
especially if it is a crystal.  There are several startup delays, including
a deliberate 1024 cycle delay to make sure the crystal oscillator is stable.

In other words, waking up from sleep takes power.


*****************************************************************
Olin Lathrop, embedded systems consultant in Devens Massachusetts
(978) 772-3129, olin@cognivis.com, http://www.cognivis.com

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