Finite State Machine Explained | Mealy Machine and Moore Machine | What is State Diagram ?

Summary

In this video, the concept of Finite State Machines (FSM) is explored, focusing on their role in representing sequential circuits. It explains the differences between Mealy and Moore machines, highlighting how outputs are generated in each type. The video covers FSM representations using state transition diagrams, state tables, and state equations. It emphasizes how the behavior of sequential circuits can be visualized with state diagrams, with a specific comparison between Mealy and Moore machine diagrams. The tutorial provides a clear understanding of how FSMs function and how to represent them using these methods.

Takeaways

• 😀 FSM (Finite State Machine) is a model used to represent sequential circuits in an abstract way.
• 😀 In combinational circuits, outputs depend only on the present inputs, while in sequential circuits, outputs depend on both the inputs and the current state of memory elements (flip-flops).
• 😀 Synchronous sequential circuits are known as FSMs because they have a finite number of internal states.
• 😀 Mealy machines generate outputs based on both the current state and present inputs to the circuit.
• 😀 Moore machines generate outputs based only on the current state of the memory elements, not the inputs.
• 😀 FSM behavior can be represented in three ways: state transition diagrams, state tables, and state equations.
• 😀 State diagrams are pictorial representations of FSM behavior, where states are represented as circles, and transitions are represented as arrows with input/output values.
• 😀 In Mealy machines, the output is displayed next to the input on the state diagram, while in Moore machines, the output is part of the state circle itself.
• 😀 State tables are another way to represent FSM behavior in tabular form, showing current states, inputs, next states, and outputs.
• 😀 In Moore machines, outputs are synchronized with clock edges, while in Mealy machines, the output depends on both the current input and state, which can change during the clock cycle.
• 😀 In Mealy machines, inputs are synchronized with the falling edge of the clock signal, and outputs are sampled just before the next clock edge.

Q & A

What is a Finite State Machine (FSM)?

A Finite State Machine (FSM) is an abstract model used to represent sequential circuits, where the output depends not only on the current inputs but also on the present state of the memory elements (flip-flops).

How do FSMs differ from combinational circuits?

In combinational circuits, the output only depends on the present inputs, whereas in sequential circuits (FSMs), the output depends on both the present inputs and the current state of the memory elements.

What are the two types of FSM models discussed in the video?

The two FSM models discussed are the Mealy machine and the Moore machine.

How does the Mealy machine generate its output?

In a Mealy machine, the output is a function of both the present state of the memory elements and the current inputs to the circuit.

What distinguishes the Moore machine from the Mealy machine?

In a Moore machine, the output depends only on the present state of the memory elements, while in a Mealy machine, the output also depends on the current inputs.

How are FSMs represented in the video?

FSMs can be represented using three methods: state transition diagrams, state tables, and state equations.

What is the purpose of a state transition diagram?

A state transition diagram visually represents the behavior of an FSM, where states are represented by circles and transitions are indicated by arrows labeled with input values that trigger the transitions.

What is the key feature of the Moore machine's state diagram?

In a Moore machine's state diagram, the output is associated with the states themselves, represented inside the state circle, and does not depend on the input.

What is a state table, and how is it useful?

A state table is a tabular representation of an FSM, showing the current state, input, next state, and output. It helps in understanding and designing FSMs by clearly outlining the state transitions and outputs.

How does the input behavior differ between Mealy and Moore machines?

In Mealy machines, the output can change within a clock cycle if the input changes, while in Moore machines, the output changes only with the state changes at clock edges.