1. Sequential Circuit Introduction to Counter
Asynchronous Counter - Ripple
Asynchronous Down Counter
Synchronous Counter – Parallel
Synchronous Counter Up/Down
Designing Synchronous Counter
Counter with Parallel Load
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2. Sequential Circuit Contents Register Introduction Shift Register
Simple register
Register with parallel load
Shift Register
Shift Register Serial In/Serial Out
Shift Register Serial In/Parallel Out
Shift Register Parallel In/Serial Out
Shift Register Parallel In/ Parallel Out
Two way shift register
Random Access Memory
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3. Sequential Circuit: Counter
Introduction
Counter is a circuit which cycle through state sequence
Two types of counter
Synchronous counter (e.g. parallel)
Asynchronous counter (e.g. ripple)
Ripple counter let some flip-flop output to be used as clock signal source for other flip-flop
Synchronous counter use the same clock signal for all flip-flop
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4. Sequential Circuit: Counter
Asynchronous Counter (Ripple)
Asynchronous Counter : flip-flop doesn’t change condition simultaneously because it doesn’t use single clock signal
Also known as ripple counter because clock signal input as ripple through counter
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5. Sequential Circuit: Counter
Asynchronous Counter (Ripple)
Example: 2-bit ripple counter
Output from one flip-flop is connected to clock input for the next flip-flop MSB
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6. Sequential Circuit: Counter
Asynchronous Counter (Ripple)
Example: 3-bit ripple counter
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7. Sequential Circuit: Counter
Asynchronous Counter (Ripple)
Example: 4-bit ripple counter (negative edge triggered)
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8. Sequential Circuit: Counter
Asynchronous Down Counter
The previous example is up asynchronous counter
Down asynchronous counter count from large to zero and repeat
Example: 3-bit binary down counter
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9. Sequential Circuit: Counter
Asynchronous Down Counter
Example: 3-bit binary down counter (MOD 8)
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10. Sequential Circuit: Counter
Synchronous Counter (Parallel)
Synchronous counter: flip-flop with the same synchronous clock signal
We can build synchronous counter using process to design sequential circuit
Example: 2-bit synchronous binary counter (using T flip-flop or JK)
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11. Sequential Circuit: Counter
Synchronous Counter (Parallel)
Example: 2-bit synchronous binary counter (using T flip-flop or JK) cont….
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12. Sequential Circuit: Counter
Synchronous Counter (Parallel)
Example: 2-bit synchronous binary counter (using T flip-flop or JK) cont….
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13. Sequential Circuit: Counter
Synchronous Counter (Parallel)
Example: 2-bit synchronous binary counter (using T flip-flop or JK) cont….
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14. Sequential Circuit: Counter
Synchronous Counter (Parallel)
Example: 2-bit synchronous binary counter (using T flip-flop or JK) cont….
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15. Sequential Circuit: Counter
Synchronous Counter (Parallel)
Example: BCD Synchronous Counter
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16. Sequential Circuit: Counter
Synchronous Counter (Parallel)
Example: BCD Synchronous Counter
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17. Sequential Circuit: Counter
Up/Down Synchronous Counter
Up/Down Synchronous Counter: two way counter which able to count up or down
Up/Down control input line which determine the counter
Up/Down = 1 (count up)
Up/Down = 0 (count down)
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18. Sequential Circuit: Counter
Up/Down Synchronous Counter
Example: 3-bit Up/Down Synchronous Counter
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19. Sequential Circuit: Counter
Up/Down Synchronous Counter
Example: 3-bit Up/Down Synchronous Counter (cont)
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20. Sequential Circuit: Counter
Designing Synchronous Counter
See sequential logic lecture notes
Example: 3-bit Gray Code Counter (using JK flip-flop)
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21. Sequential Circuit: Counter
Designing Synchronous Counter
3-bit Gray Code Counter: flip-flop input
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22. Sequential Circuit: Counter
Designing Synchronous Counter
3-bit Gray Code Counter: logic diagram
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23. Sequential Circuit: Counter
Counter with Parallel Load
Counter with Parallel Load able to
Count at different condition
Count in different sequence
For increment/decrement function
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24. Sequential Circuit: Counter
Counter with Parallel Load
Different method to get MOD-6 counter
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25. Sequential Circuit: Counter
Counter with Parallel Load
Counter with 4-bit parallel load
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26. Sequential Logic Contents Register Introduction Shift Register
Simple register
Register with parallel load
Shift Register
Shift Register Serial In/Serial Out
Shift Register Serial In/Parallel Out
Shift Register Parallel In/Serial Out
Shift Register Parallel In/ Parallel Out
Two way shift register
Random Access Memory
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