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

  • Thread starter trickae
  • Start date
  • #1
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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

Code:
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
 
Last edited:

Answers and Replies

  • #2
berkeman
Mentor
59,054
9,156
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.
 

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