> I don't like writing code for hours, minutes and seconds.  ;-)

I've done a remote switching project (via SMS) and used minutes,
1440 per day, which worked out in my scheme to be simpler to do
maths with than HhMm

All of my clocks use a very similar incrementing routine, with a small
table for month length and adjustment for 29th Feb. Alarm times are
broken down on entry to minutes and stored that way. Have used
RTCs in a couple of consumption-sensitive applications, but most
often use a kitchen clock driver

If you want to maintain long-term accuracy when on battery you
could include a link (radio, laser pointer ?) to a PIC with timing
based on mains cycles, perhaps in the house. At approximately the
same time each day the garden circuit turns on its receiver and waits
for a time stamp to come from the house unit. Would have to do
some temperature tests (freezer, hot water) to see what drift the
garden unit has

Joe



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