HI..
I find this site very helpful to students like me who are researching on how to use Atmel Attiny 2313 for traffic light controller. I would be very helpful if you send some suggestion on the circuit diagram.
Better use an CPLD instead of microcontroller !. or use an CPLD to check the states the microcontroller is giving so that two impossible states are not done due to software/or hardware error's...