Dee2034 chapter 6 register

By:
Siti Sabariah Hj. Salihin
Electrical Engineering Department
DEE2034 : DIGITAL ELECTRONICS
1
CHAPTER 6 : REGISTER

Course Learning Outcomes, CLO
Upon completion of the course, students should be able to:
 CLO 3 : Draw logics diagrams, truth tables and timing diagrams for
all common flip flops and use these to implement sequential logic
circuits correctly.

Upon completion of this Chapter, students should be able to:
6.1 Understand the concepts and applications of registers and shift
Registers.
6.1.1 Classify the Shift Register according to the methods of data
input/output: SISO, PIPO, SIPO, PISO.
6.1.2 State the applications of Shift registers listed in 6.1.1
6.1.3 Interpret the Operation and circuit of Shift Register listed in
6.1.1
6.1.4 Interpret the Operation and application of an integrated
circuits
Shift Register listed in 6.1.1
6.1.5 Explain the application of Shift Register as arithmetic circuits:
6.1.6 Explain the operations and application of Ring Counters and
Johnson Counter

Introduction – Shift Register
4
 Shift registers are constructed using several flip-
flop, connected in such a way to STORE and
TRANSFER/ Shift digital data.
 Basically, D flip-flop is used. The input data
(either ‘0’ or ‘1’) is applied to the D terminal and
the data will be stored at Q during
positive/negative-edge transition of the clock
pulse. D Q
Q

5
 One D FF is used to store 1-bit of data. Thus, the
number of flip-flops used is the same with the
number of bit stored.
 Shift register mean that the data in each FF can be
transferred/move to other FF upon edge triggering
of the clock signal.
 Four types of data movement in shift register are:-
 Parallel in / parallel out (PIPO)
 Serial in / serial out (SISO)
 Parallel in / serial out (PISO)
 Serial in / parallel out (SIPO)
Shift Register

6
Serial Parallel
•Movement of N-bit data
require N number of CLK
pulses. Thus, the operation is
slow.
•Only one FF is required to be
connected at the output
terminal, thus only one wire is
required.
•Require only one CLK pulse
to transfer all N-bit of data.
Thus, operation is faster than
serial.
•Required N number of
connection to the output
terminal, which is proportional
to the number of bit. Thus, too
many connection is required.
 Serial Data VS Parallel Data movement

7
D Q2
CP
D Q1
CP
D Q3
CP
D Q0
CP
D3 D2 D1 D0
Q3 Q2 Q1 Q0
 Flip-flop configuration for PIPO register.
CLK

Parallel in / parallel out (PIPO)
8
PIPO data movement.
Q3
Q2
CLK
Q1
Q0
1 0 1 1 1
0
0
0
0
1 0 10 0
0
0
1 1 1 1
0 0 1 0
D3
D2
D1
D0
1
0
1
0
0
1
1
0

9
 Flip-flop connection for SISO.
D Q1
FF1
CP
D Q2
FF2
CP
D Q0
FF0
CP
D Q3
FF3
CPCLK
DIN
1st CLK 2nd CLK 3rd CLK 4th CLK

Serial in / serial out (SISO)
10
SISO data movement. Binary data 10111 is transferred!
DATA-IN
Q3
Q0
Q1
1st
CLK
2nd 3rd 4th 5th
Q2
1 0 1 1 1

11
Flip-flop connection for PISO
D Q1
FF1
CP
D Q2
FF2
CP
D Q0
FF0
CP
D Q3
FF3
CPCLK
D0 D1 D2 D3SHIFT/LOAD
Serial
data
out

12
Parallel in / serial out (PISO)
 PISO data movement.
SHIFT/
LOAD
CLK
Q3
0
0 1 1 1
1 0 1
0
0
0
1
1 1 1 1
0 0 1 1
D0
D1
D2
D3
1 00 1 0 1

13
Integrated circuits Shift Register
Chips for shift registers
 74164 is a 8-bit SIPO shift register
74164
CLK
CLR
A
B
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7

14
 74165 is a 8-bit PISO register
74165
CLK
CLK INH
SH/LD
SER
D0 D1 D2 D3 D4 D5 D6 D7
Q7
Q7

15
 74195 can be used as a 4-bit PIPO
register
74195
CLK
SH/LD
J
K
Q0 Q1 Q2 Q3
CLR
D0 D1 D2 D3

 Shift Register as Divider 2 circuits
Example :
14 = 1 1 1 0
7 = 0 1 1 1
3.5= 3 = 00 1 1
1.5 = 1 = 0 0 0 1
Notes : Shift to RIGHT as divider 2.
Shift Register as arithmetic circuits:

 Shift Register as Multiplier 2 circuits
Example :
8 = 1000
16 = 10000
32 = 100000
64 = 1000000
Notes : Shift to LEFT as Multiplier 2.
Shift Register as arithmetic circuits:

18
 A shift register counter is a shift register whose
output being fed back (connected back) to the
serial input. This shift register would count the
state in a unique sequence!
 Two types of shift register counter:-
 The ring counter
 The Johnson counter
Shift Register Counters

19
Ring Counter (continue)
Ring counters are used to
construct “One-Hot”
counters
It can be constructed for any
desired MOD number
A MOD-N ring counter uses
N flip-flops connected in the
arrangement as shown in fig.
a)
In general ring-counter will
require more flip-flops than a
binary counter for the same
MOD number DEE2034 : DIGITAL ELECTRONICS

20
Ring Counter
Q3 Q2 Q1 Q0

21

22
0 0 0 1
1 0 0 0
0 1 0 0
0 0 1 0

 Exercise: Draw a 3 Bit Ring Counter
Circuit with initial input 010 . show a True
Table until 8 clock pulse/number sequence and draw the
output waveform.
 Answer:
Discuss with Your lecturer
23

24
Johnson Counter
Or Twisted-ring counter
Johnson counter constructed exactly like a normal ring counter
except that the inverted output of the last flip-flop is fed back to
first flip-flop

25
Johnson Counter
(Continue)

26
Johnson Counter
(Continue)
A
B
C
0 1 1 1
0 0 1 1
0 0 0 1

1. "Digital Systems Principles And Application"
Sixth Editon, Ronald J. Tocci.
2. "Digital Systems Fundamentals"
P.W Chandana Prasad, Lau Siong Hoe,
Dr. Ashutosh Kumar Singh, Muhammad Suryanata.
REFERENCES:
Download Tutorials Chapter 5: Register
http://www.portal.cidos.edu.my
http://www.baiasalihin.wordpress.com

28EE 202 : DIGITAL ELECTRONICS

Dee2034 chapter 6 register

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