Read this article for an example of a finite state machine design of a simple vending machine.
A sequential circuit is also called a sequential machine or a finite state machine (FSM) or a finite state automaton. This case study gives an example that illustrates the concepts of this unit for the design of a sequential circuit. A binary table represents the input/output behavior of the circuit. We use a sequential circuit, because the output also depends on the state. Recall from your readings, that state requires memory, i.e., flip flops. Thus, a binary table with entries that give the output and next state for given inputs and current state represents the design of the machine. A finite state machine diagram can also represent the design: circles represent states; arrows represent transitions next to states; and inputs and outputs label the arrows (sometimes written as input/ output). Finally, Boolean equations can also represent the design. Lastly, Karnaugh maps or Boolean logic rules can be used to simplify, i.e., minimize, the equations and, thus, the design.