Sequential Circuit

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

2
Sequential Circuit

• Contents
• Register Introduction
• 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

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

4
Sequential Circuit Counter

• Asynchronous Counter (Ripple)
• Asynchronous Counter flip-flop doesnt change
  condition simultaneously because it doesnt use
  single clock signal
• Also known as ripple counter because clock signal
  input as ripple through counter

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

6
Sequential Circuit Counter

• Asynchronous Counter (Ripple)
• Example 3-bit ripple counter

7
Sequential Circuit Counter

• Asynchronous Counter (Ripple)
• Example 4-bit ripple counter (negative edge
  triggered)

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

9
Sequential Circuit Counter

• Asynchronous Down Counter
• Example 3-bit binary down counter (MOD 8)

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)

11
Sequential Circuit Counter

• Synchronous Counter (Parallel)
• Example 2-bit synchronous binary counter (using
  T flip-flop or JK) cont.

12
Sequential Circuit Counter

• Synchronous Counter (Parallel)
• Example 2-bit synchronous binary counter (using
  T flip-flop or JK) cont.

13
Sequential Circuit Counter

• Synchronous Counter (Parallel)
• Example 2-bit synchronous binary counter (using
  T flip-flop or JK) cont.

14
Sequential Circuit Counter

• Synchronous Counter (Parallel)
• Example 2-bit synchronous binary counter (using
  T flip-flop or JK) cont.

15
Sequential Circuit Counter

• Synchronous Counter (Parallel)
• Example BCD Synchronous Counter

16
Sequential Circuit Counter

• Synchronous Counter (Parallel)
• Example BCD Synchronous Counter

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)

18
Sequential Circuit Counter

• Up/Down Synchronous Counter
• Example 3-bit Up/Down Synchronous Counter

19
Sequential Circuit Counter

• Up/Down Synchronous Counter
• Example 3-bit Up/Down Synchronous Counter (cont)

20
Sequential Circuit Counter

• Designing Synchronous Counter
• See sequential logic lecture notes
• Example 3-bit Gray Code Counter (using JK
  flip-flop)

21
Sequential Circuit Counter

• Designing Synchronous Counter
• 3-bit Gray Code Counter flip-flop input

22
Sequential Circuit Counter

• Designing Synchronous Counter
• 3-bit Gray Code Counter logic diagram

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

24
Sequential Circuit Counter

• Counter with Parallel Load
• Different method to get MOD-6 counter

25
Sequential Circuit Counter

• Counter with Parallel Load
• Counter with 4-bit parallel load

26
Sequential Logic

• Contents
• Register Introduction
• 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