Designing a Traffic Light Controller

[Your originality, thinking method and execution would be graded]

In Gotham city, traffic lights have three outputs as Red (R), Yellow (Y) or Green (G). Lets assume youre given a microchip with clock input 0.4 Hz. As you know, cars can travel when the light is Green and should not pass the traffic light when the light is Yellow or Red.

We are asked to design the traffic light controller in the busiest road of Gotham city. The controller will use directions as inputs. For example, you can use two bit inputs to represent the direction as in

N-E format: the first bit represents it is either North or South, and the second bit represents it is either East or West. If the N input is 1, traffic should be allowed in North or South direction and if the E input is 1, traffic should be allowed in East or West direction. You can assume, NO cars can make a turn in the traffic light.

Now, lets give you the details of the traffic light. We are standing in a crossroad. We want the Green light to be ON for two clock cycles. If E =1, in the second clock cycle, Green light will be ON for one more clock cycle. After terminating the Green light cycle, Yellow light cycle will be ON for one clock cycle. Then, Red light will be ON for two clock cycles. If N = 1, Red light will be ON for one more clock cycle. After this, Red and Yellow will be ON for one clock cycle and finally, the system will return to the starting state.

Please, do your best to give me the state transition diagram and state transition tables. You may use Mealy/Moore design.

According to your design, how much time it takes for the system to repeat itself (The time difference between each green light) You need to consider some different cases, please discuss.

Give me the VHDL representation of that design.