Guidelines for Determining Flip-Flop InputEquations from Next-State Map

Type Input

• D

• EN

S-R S

R

J-K J

K

Qn = 0

Qn+1=0 Qn+1=1

0 1

0 1

0 1

* 0

0 1

* *

Qn = 1

Qn+1=0 Qn+1 =1

0 1

1 0

0 *

1 0

* *

1 0

Rules for forming input map from next-state map (2)

Qn =0 half Qn =1 half

no change no change

no change complement

no change replace 1s with *s

replace 0s with *s complement

no change fill in with *s

fill in with *s complement

? Notes:

(1) * = "don't care"

(2) Always copy *s from next-state map to input map first

(3) For S, Qn=1 half and R, Qn=0 half, fill remaining entries with 0s.

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