Question: Design mealy sequence detector to detect a sequence ----1010---- using D filpflop and logic
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Mumbai University > ELECTRO > Sem 3 > Digital Circuits and Designs

Marks: 10M

Year: Dec 2014

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modified 3.2 years ago  • written 3.2 years ago by gravatar for Pooja Joshi Pooja Joshi740
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  • A sequence detector is a sequential state machine. In a Mealy machine, output depends on the present state and the external input (x). Hence in the diagram, the output is written outside the states, along with inputs. The state diagram of a Mealy machine for a 1010 detector is:

enter image description here

  • The state table for the above diagram:

enter image description here

  • State assignments: Let $S_0$ = 00

$S_1$ = 01

$S_2$ = 10

$S_3$ = 11

The above state table becomes:

enter image description here

  • Four states will require two flip flops. Consider two D flip flops. Their excitation table is shown below.

  • Excitation table:

enter image description here

  • K-maps to determine inputs to D Flip flop:

enter image description here

  • Circuit diagram for the sequence detector:

enter image description here

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written 3.2 years ago by gravatar for Pooja Joshi Pooja Joshi740

if i design it using 5 states, is the method wrong in case of mealy FSM?

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written 21 months ago by gravatar for raghavaggarwal19 raghavaggarwal190
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