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Encoder and Decoder

This document discusses encoders, decoders, and seven-segment displays. It defines encoders as circuits that produce a binary output code based on activated inputs, and decoders as circuits that convert a binary code into a single numeric output. It provides examples of encoders and decoders, and describes how a BCD to seven-segment decoder/driver works to display a decimal number on a seven-segment LED display based on a binary-coded decimal input. It includes examples of using specific ICs like the 74147 and 74LS42 as encoders and decoders.

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615 views17 pages

Encoder and Decoder

This document discusses encoders, decoders, and seven-segment displays. It defines encoders as circuits that produce a binary output code based on activated inputs, and decoders as circuits that convert a binary code into a single numeric output. It provides examples of encoders and decoders, and describes how a BCD to seven-segment decoder/driver works to display a decimal number on a seven-segment LED display based on a binary-coded decimal input. It includes examples of using specific ICs like the 74147 and 74LS42 as encoders and decoders.

Uploaded by

Ureyno
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PPTX, PDF, TXT or read online on Scribd
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Teknik Digital

Zulhelman
Encoding, Decoding, and
Seven-Segment Displays

Encoder/Decoder Vocabulary
ENCODER- a digital circuit that
produces a binary output code
depending on which of its inputs are
activated.
DECODER- a digital circuit that converts
an input binary code into a single
numeric output.

ENCODERS AND DECODERS


A

A
A

ENCODER

DECODER

O
O

ONLY ONE INPUT


ACTIVATED AT A TIME
BINARY CODE OUTPUT

4
5

BINARY CODE INPUT


ONLY ONE OUTPUT
ACTIVATED AT A TIME

THE 8421 BCD CODE


BCD stands for Binary-Coded Decimal.
A BCD number is a four-bit binary group that
represents one of the ten decimal digits 0 through 9.
Example:

Decimal number 4926

8421 BCD coded number 0100 1001 0010 0110

ELECTRONIC ENCODER DECIMAL TO BCD


BCD output
Decimal input

7
5
3

00
10
0
11
Decimal
to
BCD
Encoder

Encoders are available in IC form.


This encoder translates from decimal
input to BCD output.

10 line to 4 line Encoder

10 line to 4 line Encoder


BINARY (BCD)

DECIMAL
8
ENCODER
9 5V
8 5V
7 5V
6 5V
5 5V
4 5V
3 5V
2 5V
1 5V

I9
I8
I7
I6
I5
I4
I3
I2
I1

74147
A3
A2
A1
A0

4 line to 10 line Decoder


DECIMAL
9
8
DECODER
BINARY (BCD)

8 0V
4 0V
2 0V
1 0V

74LS42

A3
A2
A1
A0

7
9
8
7
6
5
4
3
2
1
0

6
5
4
3
2
1
0

DECODERS: BCD TO
7-SEGMENT DECODER/DRIVER
Decimal output
LED

BCD input

0 10 01 01
BCD-to7-Segment
Decoder/
Driver

Electronic decoders are available in IC form.

This decoder translates from BCD to decimal.


Decimals are shown on an 7-segment LED display.
This IC also drives the 7-segment LED display.

TEST
Q #4#5- What is the decimal output from the decoder that
#1#2#3appears on the 7-segment display?

Answer: 6
3
0
9
7

BCD input

Decimal output

010 100 010 0110


BCD-to7-Segment
Decoder/
Driver

BCD-T O-SEVEN SEGMENT DECODER DRIVER


V+

abcdef g .

5V

74LS47
A3
g
A2
f
A1
e
A0
d
c
b
a
test
RBI RBO

TEST
A

ENCODER

INPUT O3 O2 O1 O0
A1=1
A4=1
A6=1
A8=1

TEST
A
A

A
A

DECODER

O
O

O
O

O
O

O
O

O
O

A3
0
0
0
1

A2
0
1
1
0

A1
0
0
1
0

A0 OUTPUT
0
1
1
1

TEST
ANSWER THE FOLLOWING QUESTIONS WITH ONE OR MORE
OF THESE WORDS: MUX, DEMUX, ENCODER, DECODER.
A. Has more inputs than outputs. ENCODER, MUX
B. Uses select inputs. MUX, DEMUX
C. Can be used in parallel-to-serial conversion. MUX
D. Produces a binary code at its output. ENCODER
E. Only one of its outputs is activated at one time. DEMUX, DECODER
F. Used to route input signals to one of several outputs. MUX
G. Used to generate arbitrary logic functions. MUX, DEMUX
H. 3 line-to-8 line or binary to octal. DECODER
I. Data Selectors are also MUX.

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