PeterH:
Yes, that seems like the way to do it. Three wires, and cheap and readily available hardware at each node.I wouldn't fancy building and connecting thousands of those by hand, though. Maybe you could find a cheap fab house willing to do a production run for you?
I understand that what Boffin & CrossRoads are saying is the way to do it, but you're right, Peter, that would take AGES to wire up a half-mile of everything.
Since I haven't really gotten a clear answer, I will ask everyone again: With Boffin's & CrossRoads concept in mind, why can't I just use programmable LED strip lights that are already wired together and have a microcontroller at each node? Why have a fab house do it when it's basically already done in LED strip lights? Wouldn't this work the same way, or am I missing some important facts about programmable LED strip lights?