Important terminologies - mbits-mirafra/digitalDesignCourse GitHub Wiki
Input Variables:
In a finite state machine, an input variable is a variable or signal that is used as an input to the state machine.
Output Variables:
An output variable is a variable or signal that is used to produce an output based on the current state and input values of the machine.
State Variables:
In a finite state machine, a state variable is a variable that represents the current state of the machine. It is a variable that is used to keep track of the current state of the system, and to determine what state the machine will transition to based on the input it receives.
For Example, state variables can be represented as A,B,C,D or 00,01,10,11 and so on.
In general state variables are flip flop outputs.
Excitation Variables:
In a finite state machine, an excitation variable is a variable that is used to determine the next state of the machine based on the current state and input values. It is a variable that controls the transition from the current state to the next state of the machine.
Excitation Variables are the inputs to the memory (flip flops). The name excitation variable is used because the variable excites the memory to change.
State:
In a finite state machine (FSM), a state is a condition or situation that the system can be in at a particular moment. It represents a specific mode of operation or behavior of the system, which can be determined by the current values of the input, output, and state variables.
Present State:
The present state refers to the current state of the machine at a particular moment. It is the state that the machine is in at the beginning of a cycle or when it receives input.
The status of all state variables, at some time t, represents a condition called Present state.
Next state:
In a finite state machine (FSM), the next state refers to the state that the machine will transition to based on the current state and input values.
The status of all state variables, at some time t+1, represents a condition called next state.
State Diagram:
- A state diagram is a graphical representation of FSM.
- A state is represented by a circle, and the transition between states is indicated by directed lines (or arcs) connecting the circles. Input conditions that cause state changes to occur and the resulting output signals are written adjacent to the directed arc.
State Table:
- The state table representation of a sequential circuit consists of three sections labeled present state, next state and output.
- The present state designates the state of flip-flops before the occurrence of a clock pulse.
- The next state shows the states of flip-flops after the clock pulse, and the output section lists the value of the output variables during the present state.