Hi,
Thanks for the push on State Machines. I once told the vendor of a $200,000 semiconductor tool that we wouldn't buy it until they provided us with a State Machine diagram of the factory communications interface. They grumbled for 3 months, sent the diagram, and said "Oh, there's a major upgrade of the software we just installed".
Here's a State Machine example for a Traffic Light that includes vehicle detection on the side street and a Walk request button. This is in a preprogrammed example package for young kids starting to connect hardware to Arduino.
Awww. it didn't fit in 9000 bytes. Ummm...
OK, put it on my wiki here: (NOT good formatting. I will figure it out.. )
https://arduinoinfo.mywikis.net/wiki/Easy-Connect-Software-Outline
Scroll down to last example..