The outputs of a state machine are simple combinational circuits. The inputs to the circuit are the outputs of the state machine flip-flops or simply the state of the machine. The outputs of this logic are the outputs of the system itself. This section will build on the concepts described above by using an example that will demonstrate the detailed process. A simple traffic light controller is implemented by the following circuit and our task is to obtain its state diagram.
Lets begin by using the three steps described in the overview section.
The first step is to determine the number of states or at least the upper bound. This machine has two flip-flops and therefore consists of four or fewer states. The second step is to determine the state transitions. We will begin by labeling several of the internal nodes on the schematic. The labeled schematic is included below.