I'm using a 'F874 in a small logging system with a RTC etc.
The data to be logged at this stage is Temperature and Humidity with
some uncommitted digital and analog inputs, the logging period is going
to be programmable from around 1 to 60 minutes continuing until the
memory is full.
I am planning to put the pic to sleep, wake up and check the RTC and if
required, read data & store, then doze off again. I understand that the
more frequently the waking is done, the more accurate the logging
interval will be, but is there a rule of thumb for this sort of thing or
am I approaching it from the wrong angle?

thanks
rob