1 of 26

Ali Adib Arnab�Senior Lecturer and Chairman, Department of Electrical and Electronic Engineering�University of Global Village�MSc in Telecommunication and Wireless Systems and Management, Queen Mary University of London

My Google Site Link: https://sites.google.com/view/ali-adib-arnab/home

2 of 26

Topic 5

Synchronous Sequential Logic

3 of 26

Latches

  • SR Latch

3

S R

Q

0 0

Q0

0 1

0

1 0

1

1 1

Q=Q’=0

No change

Reset

Set

Invalid

C S R

Q

0 x x

Q0

1 0 0

Q0

1 0 1

0

1 1 0

1

1 1 1

Q=Q’

No change

No change

Reset

Set

Invalid

  • SR Latch with Control Input

4 of 26

Controlled Latches

  • D Latch (D = Data)

Eastern Mediterranean University

4

C D

Q

0 x

Q0

1 0

0

1 1

1

No change

Reset

Set

C

Timing Diagram

D

Q

t

Output may change

D

Q

Q

Q (t+1) = D

When Clock is enabled

​

Q(t+1) = Q(t)

When Clock is disabled

5 of 26

Controlled Latches (Task 1)

  • D Latch (D = Data)

Eastern Mediterranean University

5

C D

Q

0 x

Q0

1 0

0

1 1

1

No change

Reset

Set

C

Timing Diagram

D

Q

t

Output may change

D

Q

Q

Q (t+1) = D

When Clock is enabled

​

Q(t+1) = Q(t)

When Clock is disabled

6 of 26

Controlled Latches

  • D Latch (D = Data)

Eastern Mediterranean University

6

C D

Q

0 x

Q0

1 0

0

1 1

1

No change

Reset

Set

C

Timing Diagram

D

Q

Output may change

D

Q

Q

Q (t+1) = D

When Clock is enabled

​

Q(t+1) = Q(t)

When Clock is disabled

7 of 26

Flip-Flops

  • T Flip-Flop

Eastern Mediterranean University

7

D = TQ’ + T’Q = T ⊕ Q

J

Q

Q

K

T

D

Q

Q

T

D = JQ’ + K’Q

T

Q

Q

8 of 26

Flip-Flops

  • Master-Slave D Flip-Flop

Eastern Mediterranean University

8

D Latch

(Master)

D

​

C

Q

D Latch

(Slave)

D

​

C

Q

Q

D

CLK

CLK

D

QMaster

QSlave

Looks like it is negative edge-triggered

Master

Slave

9 of 26

Flip-Flops

  • JK Flip-Flop

Eastern Mediterranean University

9

J

Q

Q

K

D = JQ’ + K’Q

Q (t+1) = D = JQ’ + K’Q

J

K

Q(t+1)

0

0

Q(t)

0

1

0

1

0

1

1

1

Q’(t)

10 of 26

Flip-Flop Characteristic Equations

  • Analysis / Derivation

Eastern Mediterranean University

10

J

Q

Q

K

J

K

Q(t)

Q(t+1)

0

0

0

0

0

0

1

1

0

1

0

​

0

1

1

​

1

0

0

​

1

0

1

​

1

1

0

​

1

1

1

​

No change

​

Reset

​

Set

​

Toggle

11 of 26

Flip-Flop Characteristic Equations

  • Analysis / Derivation

Eastern Mediterranean University

11

J

Q

Q

K

J

K

Q(t)

Q(t+1)

0

0

0

0

0

0

1

1

0

1

0

0

0

1

1

0

1

0

0

​

1

0

1

​

1

1

0

​

1

1

1

​

No change

​

Reset

​

Set

​

Toggle

12 of 26

Flip-Flop Characteristic Equations

  • Analysis / Derivation

Eastern Mediterranean University

12

J

Q

Q

K

J

K

Q(t)

Q(t+1)

0

0

0

0

0

0

1

1

0

1

0

0

0

1

1

0

1

0

0

1

1

0

1

1

1

1

0

​

1

1

1

​

No change

​

Reset

​

Set

​

Toggle

13 of 26

Flip-Flop Characteristic Equations

  • Analysis / Derivation

Eastern Mediterranean University

13

J

Q

Q

K

J

K

Q(t)

Q(t+1)

0

0

0

0

0

0

1

1

0

1

0

0

0

1

1

0

1

0

0

1

1

0

1

1

1

1

0

1

1

1

1

0

No change

​

Reset

​

Set

​

Toggle

14 of 26

Mealy and Moore Models

  • The Mealy model: the outputs are functions of both the present state and inputs
    • The outputs may change if the inputs change during the clock pulse period.
      • The outputs may have momentary false values unless the inputs are synchronized with the clocks.
  • The Moore model: the outputs are functions of the present state only.
    • The outputs are synchronous with the clocks.

​

​

Eastern Mediterranean University

14

15 of 26

Mealy and Moore Models

Eastern Mediterranean University

15

Fig. 5.21 Block diagram of Mealy and Moore state machine

16 of 26

Mealy and Moore Models

Eastern Mediterranean University

16

Present State

I/P

Next State

O/P

A

B

x

A

B

y

0

0

0

0

0

0

0

0

1

0

1

0

0

1

0

0

0

1

0

1

1

1

1

0

1

0

0

0

0

1

1

0

1

1

0

0

1

1

0

0

0

1

1

1

1

1

0

0

Mealy

For the same state,�the output changes with the input

Present State

I/P

Next State

O/P

A

B

x

A

B

y

0

0

0

0

0

0

0

0

1

0

1

0

0

1

0

0

1

0

0

1

1

1

0

0

1

0

0

1

0

0

1

0

1

1

1

0

1

1

0

1

1

1

1

1

1

0

0

1

Moore

For the same state,�the output does not change with the input

17 of 26

Binary Counter Example

  • How about a random number generator.
  • Check the following state diagram and try to identify what it is trying to do :

​

Eastern Mediterranean University

17

18 of 26

Binary Counter Example

  • How about a random number generator.
  • Check the following state diagram and try to identify what it is trying to do :

​

Eastern Mediterranean University

18

19 of 26

Binary Counter Example

  • How about a random number generator.

​

Eastern Mediterranean University

19

20 of 26

Memory Hierarchy

21 of 26

Registers

  • Group of storage elements read/written as a unit
    • Store related values (e.g. a binary word)
  • Collection of flip-flops with common control
    • Share clock, reset, set lines
  • Example:
    • Storage registers
    • Shift registers
    • Counters

21

22 of 26

Storage registers

  • Basic storage registers use flip-flops
  • Example: 4 bit storage register

22

23 of 26

ROM

23

24 of 26

ROM

24

25 of 26

Function table

25

​

​

0  0

0   1

0  1

1   0

1  0

1   1

1  1

1   0

F0 (A,B) = A’B+AB’+AB

​

F1(A,B) = A’B’

​

22 x 2

ROM

2 bit Input

(Address)

2 bit Output

(Data)

A B F0 F1

26 of 26

Published Papers��[1] Ali Adib Arnab, Sheikh Sadia Afrin, F.M. Fahad, Hasan U. Zaman, "A cost effective way to build a web controlled search and CO detector rover," DOI:10.1109/CCWC.2017.7868451 (Received the track Best Paper Award), Proceedings of the 7th IEEE Annual Computing and Communication Workshop and Conference (IEEE CCWC 2017), Las Vegas, USA, 9-11 January, 2017, Publisher: IEEE�[2] Ali Adib Arnab, Sheikh Md. Razibul Hasan Raj, John Schormans, Sultana Jahan Mukta, Nafi Ahmad "Analysis of the Cost of Varying Levels of User Perceived Quality for Internet Access," https://doi.org/10.1007/978-3-030-68154-8_36 , Proceedings of the 3rd International Conference on Intelligent Computing & Optimization – ICO 2020, Hua Hin, Thailand, 22-23 April, 2021, Publisher: Springer

  • Research and Teaching Interests: 
  • Wireless and Mobile Communication
  • Telecommunication Engineering
  • Communication Theory
  • Electronics
  • Internet of Things
  • Digital Electronics
  • Renewable Energy
  • VLSI

​