I see there are a few projects, for instance Dan Geiger’s is pretty well developed. However it kind of looks like these projects came and went i.e. they weren’t further refined.
It would be nice if a company like Sparkfun were to start producing a kit form of e.g. his watch, and continue to refine it. If each person is reinventing the wheel that isn’t too efficient.
The following is based on a PIC chip, and is a calculator as the main feature. But there is no reason to think an AVR with Arduino code on it can’t do this.
And I wonder, how small of a battery can an Arduino and an OLED screen run off of?
How much power does a small around lithium battery provide?
Size is the wrong requirement to worry about at this point. It can run on most batteries. The question is for how long. Start thinking from the other end. How much does it need? How much can you save power. How much can you reduce the operating current for endurance while maintaining functionality and (quite important for a watch) timing accuracy. There is no point in wearing a watch that works for a day or a few weeks before changing batteries. Strip an arduino to it’s bare essentials and research low-current consumptions techniques.
Valen:
The following is based on a PIC chip, and is a calculator as the main feature. But there is no reason to think an AVR with Arduino code on it can’t do this.
That is pretty interesting. It’s a bit rudimentary though…
I think he made more videos where he talked about how he did his uWatch. But he made a lot since then (up in the 800s). And I don’t know which episodes. Go visit http://www.eevblog.com/episodes/ for more. And it is probably extensively discussed on his forum.