Generaly when designing mealy or moore ckts when to pick which?

[trickae]

Homework Statement

Not really a HW question but say we follow the steps in converting a state diagram down to its excitation table - how do we determine whether the best ckt implementation would be best implemented with either a mealy or a moore system

Homework Equations

mealy :
state equation : Q = f(present state, current inputs)
output equation: Z = h(present state, current inputs)

Moore :
state eqaution : Q = f(present state, current inputs)
output equation: Z = h(present state)

The Attempt at a Solution

1) granted we 're given a function for a truth table
f(A,B,C,D...,etc) = logic function

2) we convert it into a state / excitation table depending on the kind of flip flops we want to use

D flip flop: 

q  Q | D
0..0    0  
0  1    1
1  0    0
1  1    1

not Q = C' . d + Q.D
or Q = D

T flip flops

q  Q | T
0  0    0
0  1    1
1  0    1
1  1    0

Q = Tq' + T'q

J/K flip flops

q Q | J  K 
0 0    0 x
0 1    1 x
1 0    x 1
1 1    x 0

let x = don't care values

Q = Jq' + K'q

 

[berkeman]

I generally use the Moore structure, and I think it is the more commonly used. I think you would only use the Mealy structure if you needed to propagate input changes through the structure a clock earlier than you get with the Moore.

 

[piercas]

When designing a circuit, whether it is better to use a Mealy or Moore system depends on the specific needs and requirements of the circuit. Both types have their advantages and disadvantages, and it is important to consider these factors when making a decision.

A Mealy circuit has outputs that are dependent on both the current inputs and the current state. This means that it can respond quickly to changes in inputs, but it may also produce more complex output equations. On the other hand, a Moore circuit has outputs that are only dependent on the current state, making it simpler to design and implement. However, it may not respond as quickly to changes in inputs.

To determine which type of circuit would be best for a particular design, it is important to consider factors such as the complexity of the output equations, the speed of response needed, and the overall goals of the circuit. For example, if the circuit needs to respond quickly to changes in inputs and the output equations are not too complex, a Mealy circuit may be the best choice. However, if the circuit needs to be simple and efficient, a Moore circuit may be a better option. Ultimately, the decision should be based on the specific requirements and goals of the circuit.

 

[piercas]

When designing mealy or moore circuits, the decision of which to use depends on the specific requirements and constraints of the system. Mealy circuits are generally more complex and have more gates, but they can respond faster to inputs and have more flexibility in terms of output functions. Moore circuits, on the other hand, are simpler and have fewer gates, but they may have a slower response time and limited output functions.

One way to determine which type of circuit would be best is to consider the complexity of the output function. If the output function is complex and depends on both the present state and current inputs, a mealy circuit may be more suitable. This is because the output function can be directly incorporated into the state equation, making the circuit more efficient.

On the other hand, if the output function is simple and only depends on the present state, a moore circuit may be a better choice. This is because the output function can be directly mapped to the output equation, simplifying the circuit and reducing the number of gates.

Another factor to consider is the speed of the system. Mealy circuits can respond faster to inputs, as the output is directly affected by the current inputs. Moore circuits, on the other hand, have a slight delay as the output is only updated when the system transitions to a new state. If speed is a critical factor, a mealy circuit may be more suitable.

In summary, the decision to use a mealy or moore circuit ultimately depends on the specific requirements and constraints of the system. A thorough analysis of the output function, speed requirements, and complexity of the circuit can help determine the best implementation.