current state diagram for a railway station

Because we have no moving barriers available to implement the gate, we will implement it
in the form a blinking light. For this purpose, we wish to have a circuit with the following
specification:
• The circuit has a single input g and a single output x ; input g activates the blinking
light, output x represents the light.
• As long as g =0 output x remains 0 .
• As long as g =1 output x will change value with a frequency of 1 Hz; that is: x
will become 1 for half a second, then become 0 for half a second, then become 1
for half a second again, and so on.
• If, when g =1 and x=1 , input g becomes 0 , then the 0.5 -second period in which
x is required to stay 1 is fully completed, before x becomes 0 again and the
blinking stops. So, whenever x=1 it will always remain 1 for exactly half a second,
independently of g .
• Use the 4 Hz signal available on the BOX as clock for this circuit.
Construct a State-Transition diagram for this circuit. How many states do you need, when
the circuit is triggered by a 4 Hz clock? Design a sequential circuit, according to the rules
of the trade, and build and test it on the BOX. Keep this circuit for what follows.