1. Counters & Sequential Circuit Design

2. Sequential Logic Design
Contents
Why sequential logic?
Flip-flop criteria table
Sequential circuit analysis
Sequential circuit design

3. Why Sequential Logic?
Sequential circuit has additional dimension which is time
Combinational logic only depends on current input
Sequential circuit output depends on previous input other than current input
More powerful than combination logic
Able to model condition which can’t be modeled by combinational logic

4. Counters 2-bit Asynchronous

5. 3-bit Asynchronous

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2-bit Synchronous
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3-bit Synchronous
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8. Sequential Circuit Analysis

9. Sequential Circuit Analysis
From the state equations and output function, we can derive state table which contains all combined binary available for current condition and input
State table
The same as Truth Table
Input and condition pad on the left
Output and next condition on the right
combined binary available for current condition and input
M flip-flop and n input => 2m+n line

10. Design of Synchrounous counters and statemachine (Menu)
1.Make State diagram
2.Make next state table
3.Choose Flip-Flops and make Flip-Flop-transition table
4. Make logic expressions(now without Karnaught)
5. Draw Implementation

11. Sequential Circuit Analysis
From the truth table, we can draw state diagram
State diagram
Each state is represented by circle
Each arrow (between two circle) represent transfer for sequential logic (i.e. line transition in truth table)
a/b label for each arrow where a represent inputs and b represent output for circuit in transition
Each flip-flop value combination represent state. Therefore, m flip-flop=> until 2m state.

12. Sequential Circuit Analysis step1. make state diagram

13. Sequential Circuit Analysis step2. make state next state table
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14. Sequential Circuit Analysis step3. choose flip-flops
With 8 states we need 3 flipflops !
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15. Sequential Circuit Analysis step3. Transitiontable JKFF
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16. Sequential Circuit Analysis step4. Logic expressions
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17. Sequential Circuit Analysis step4. Logic expressions
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18. Sequential Circuit Analysis 5. Draw Implementation
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Counter decoding
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Counter decoding
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