We should split this topic, what's a good starting post to do that?
Seems to me all but the very first message are off the original topic. Speaks to our forum discipline :-)
I think you could separate right there.
In terms of specs I would think:
a) Eliminate the regulator
b) Eliminate the resonator
c) Potentially switch to 328pb
Then comes the timer question. Part of this is being able to run lower power than with the WDT or listen mode. And part of it is being able to track time more precisely. I think some options are:
1) tpl5010 - super simple, super small, very low power timer. Not precise.
2) am1815 - super low power RTC, not temp corrected.
3) 32.768khz crystal on 328p - this gives you a precision timer at <1uA. But a lot needs to be done in software.
1) could probably just take the place of the regulator given how small it is. Same for 3) and the resonator. If you want to add 2) you probably need to let go the flash - it wouldn't hurt me, I've never had much use for it.
With 1) or 2) you'd have the lowest power arduino clone on the market. At least last time I checked nobody had that.
I think 2) is more attractive overall. But it has the difficult package issue.
I guess another thing to consider is throwing in a si7021 at least as option. Everybody should have a handful TH motes at home and it would be great to have something less expensive than the Moteino + Weathershield option available.
Joe