I decided to add the sleep.h library to a sketch to try to minimize power use. This is something I did successfully a couple of years ago.
But when I include the library in my sketch, it can't find it. So I figured I would just add it to the location where it is looking for it. I have added it to about 10 different library & libraries folders, and it still doesn't see it.
You would think that the IDE would show the folder it is looking in, or show it in the preferences. But I am dmnd if I can find it.
I know I created this problem myself tho. A couple of years ago when I was learning for the first time, I naturally assumed that my choice for a sketch and library location (somewhere on C or D drive) made much more sense than this users/roaming junk. And over the course of years, I seem to have forgotten what I did previously, and now I have Arduino, Arduino 1.01 and I don't know what all all over two hard drives.
I think it is time to bite the bullet and just trash everything related to Arduino (after hiding all my sketches and all the libraries I can find), and do a clean install.
User libraries and Library Manager installed/updated libraries are added to the libraries folder under your sketchbook folder. To find the sketchbook folder look at Tools > Preferences > Sketchbook Location:. If you want to find out where any particular library is you can open one of its example sketches from File > Examples and then do Sketch > Show Sketch Folder.
thanks.
It is working now, but it was a little odd. The first place I copied sleep.h to was the sketch folder, and then used #include <sleep.h> - with no luck. That is when I began broadcasting the file to every folder that would hold still, still no worky (and that's when my frustration inspired me to ask for advice).
After I had posted, I tried copying the avr folder into the sketch folder, and used #include <avr/sleep.h>, and it worked. Of course, it was very late and it is possible that I goofed it up somehow. In any case, thanks for the explanation.
But after all the folderol, I put a nano (not in a circuit, just hanging on the USB cable) with the bare minimum sketch, to sleep (power down mode), and it still draws 14mA (per my USB power meter). That is a lot more than I expected and disappointing. I had expected in the uA's (although I guess the power LED draws about 2.5mA).