ECE 301 – Digital Electronicsece.gmu.edu/~clorie/Spring11/ECE-301/Lectures/Lecture_25.pdfECE 301...
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ECE 301 – Digital Electronics FSM Design Examples (Lecture #25) The slides included herein were taken from the materials accompanying Fundamentals of Logic Design, 6 th Edition, by Roth and Kinney, and were used with permission from Cengage Learning.
Transcript of ECE 301 – Digital Electronicsece.gmu.edu/~clorie/Spring11/ECE-301/Lectures/Lecture_25.pdfECE 301...
ECE 301 – Digital Electronics
FSM Design Examples
(Lecture #25)
The slides included herein were taken from the materials accompanying
Fundamentals of Logic Design, 6th Edition, by Roth and Kinney,
and were used with permission from Cengage Learning.
Spring 2011 ECE 301 - Digital Electronics 2
Sequential Circuit Design1. Understand specifications
2. Draw state graph (to describe state machine behavior)
3. Construct state table (from state graph)
4. Perform state reduction (if necessary)
5. Assign a binary value to each state (state assignment)
6. Create state transition table
7. Select type of Flip-Flop to use
8. Derive Flip-Flop input equations and FSM output equation(s)
9. Draw circuit diagram
Spring 2011 ECE 301 - Digital Electronics 3
FSM Design
Example #1:
Design a sequence detector that outputs a 1 when either 011 or 101 is detected.
The FSM does not reset when a sequence is detected.
Requirements:
1. Mealy machine2. Binary state-assignment
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Example #1: State Graph
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Example #1: State Table
Present Next State Output
State X = 0 X = 1 X = 0 X = 1
Spring 2011 ECE 301 - Digital Electronics 6
Example #1: State Reduction
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Example #1: State Transition Table(using Binary state assignment)
A+B+C+ Z
ABC X = 0 X = 1 X = 0 X = 1
Spring 2011 ECE 301 - Digital Electronics 8
FSM Design
Example #2:
Design a sequence detector that outputs a 1 when either 11 or 010 is detected.
The FSM does not reset when a sequence is detected.
Requirements:
1. Mealy machine2. Binary state-assignment3. JK Flip-Flops
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Example #2: State Graph
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Example #2: State Table
Present Next State Output
State X = 0 X = 1 X = 0 X = 1
Spring 2011 ECE 301 - Digital Electronics 11
Example #2: State Reduction
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Example #2: State Transition Table(using Binary state assignment)
A+B+ Z
AB X = 0 X = 1 X = 0 X = 1
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Example #2: JK Excitation Table
Q Q+ J K
0 0 0 x
0 1 1 x
1 0 x 1
1 1 x 0
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Example #2: State Transition Table
A+B+ JAKA JBKB
AB X = 0 X = 1 X = 0 X = 1 X = 0 X = 1
(using Binary state assignment)
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Example #2: FF Input Equations
JA = KA =
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Example #2: FF Input Equations
JB = KB =
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Example #2: FSM Output Equation
Z =
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Example #2: FSM Circuit Diagram
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FSM Design
Example #3:
Design a sequence detector that outputs a 1 when either 11 or 010 is detected.
The FSM does not reset when a sequence is detected.
Requirements:
1. Mealy machine2. Binary state-assignment3. T Flip-Flops
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Example #3: T Excitation Table
Q Q+ T
0 0 0
0 1 1
1 0 1
1 1 0
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Example #3: State Transition Table(using Binary state assignment)
A+B+ TA TB
AB X = 0 X = 1 X = 0 X = 1 X = 0 X = 1
Spring 2011 ECE 301 - Digital Electronics 22
Example #3: FF Input Equations
TA = TB =
Spring 2011 ECE 301 - Digital Electronics 23
Example #3: FSM Output Equation
Z =
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Example #3: FSM Circuit Diagram
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Questions?
