Finite state machine and it's types and working
- 1. Seminar (ECD 1702) Department of Electronics and Communication Engineering NIT Mizoram Topic : Finite State Machine Presented by: Priya Devi & Yuvraj Singh
- 2. Finite State Machine • Introduction • Mealy Machine • Moore Machine • Comparison
- 3. Introduction: • FSM's can exist in several states and it goes from one state to another state based on the present state and the input conditions • Any synchronous circuit is an FSM of some form • This means that: Combinational logic is an FSM without memory Flip-Flops and counters are also FSM's
- 4. General FSM • There are 3 (S0, S1, S2) states so we need a minimum of 2 states variables (A,B) and 2 Flip-Flops. • The generalized circuit diagram is as show below:
- 5. General F SM • The circuit diagram consists of: ➤Combinational block: with primary input w and primary output z. it also consist of secondary inputs (present state) and secondary outputs (next state) ➤ Memory block: consist mainly of Flip-Flops.
- 6. Example There are numerous examples of everyday devices that are controlled by a state machine: • Traffic light • Garage Door Numeric Keypad • Vending Machine
- 7. Outputs of state machines: • No provision has been made to show the output z which is different from the state variables. The output can therefore be modelled in two distinct ways ➤ Moore machines ➤ Mealy machines
- 8. ➤D = F(W,Q) ➤Z = G(Q) ➤F and G are Boolean functions ➤Output only depends on the current state (Q) ➤Input (W) and current state (Q) determine the next state (D)
- 9. ➤ D = F ( W,Q ) ➤ Z = G( W,Q ) ➤ Fand G are Boolean functions ➤ Output depends on both current state (Q) and input (W) ➤ Next state (D) depends on input (W) and current state (Q)
- 10. Comparison: Moore vs Mealy • Output Timing • Complexity of State Design • Response Time to Input Changes • Applications • Design Complexity
- 11. Choosing between Moore and Mealy machines • It actually comes down to the task at hand when choosing between Mealy and More machines • These are a few questions to ask when choosing between either of the two: Does one want to have a synchronous or asynchronous machine? Is speed paramount? Are both the inputs and present state readily available? • The answer to each of these questions determines the type of machine that would work best.
- 12. Thank you