odometer:
You are trying to kill an ant with a howitzer.
And the TimeAlarms libraries are almost certainly more trouble than just writing the thing from scratch.
I would disagree.
I like to get things done and actually finish a project to be able to put it to bed without having to monkey around with it. As soon as you do anything "real" that will involve daylight savings time or timezones things will start to get messy.
TimeAlarms is quick and easy to use and supports several different types of events/timers/alarms.
Yeah, I've written stuff like this from scratch before, but having done that, and having used these types of epoch based libraries MANY times over the decades and having the flash code space available in the AVR to be able to use more generalized libraries, I'd still recommend using Time & TimeAlarms libraries as it can provide a much quicker and easier path to project completion.
Using these types of libraries allows putting a clean abstraction layer between the main code and the h/w which keeps the main line code clean and allows it to focus on the overall task vs having to sprinkle h/w specific code all over the place which makes any potential maintenance more difficult.
I'm a big believer in layered s/w design.
I've used the libraries I've mentioned earlier on several personal clock projects.
But then I've been doing embedded s/w development and *nix development for 35+ years...
And I am sure that this is all Greek to the OP.
This I believe. And I'm guessing that this is the #1 reason that most people will shy away from using epoch based time tracking.
They are not grasping the concept and its usefulness.
Why even use an Arduino? Why not just use one of these?
http://www.homedepot.com/p/Intermatic-15-Amp-Plug-In-Lamp-and-Appliance-Timer-White-TN111K/205478759
I was thinking more along the lines of a X10 computer interface.
It is programmable and the built intelligence, can calculated sunrise/set for any georgraphic location, and supports macros for doing more than simple independent on/off things.
--- bill