Finite State Machine and its Diagrams

Definition:

A State machine is a machine that has finite state (conditions) used to have some desired output. Basically a state machine is like a switch box that switches between states. It is defined with a FSM chart. 

Components of a State Machine:

A State machine chart is composed of the following components

1. States
2. Transitions
3. Conditions
4. Start and Stop states

Designing of a State Machine:

A State machine is designed with the following steps..

• Step 1: Describe the machine in words.

In this example, we’ll be designing a controller for an elevator. The elevator can be at one of two floors: Ground or First. There is one button that controls the elevator, and it has two values: Up or Down. Also, there are two lights in the elevator that indicate the current floor: Red for Ground, and Green for First. At each time step, the controller checks the current floor and current input, changes floors and lights in the obvious way. 

• Step 2: Draw the FSM Diagram:

• Step 3: Simplify in the form of 0's and 1's:

• Step 4: Draw the Truth Table:

• Step 5: Draw the Big Picture View of the Circuit:

• Step 6: Find all the Boolean Expressions:

• Step 7: Draw the Simplified Circuit known as FSM :)