encoders decoders

8/6/2019 Encoders Decoders

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Digital ElectronicsDigital ElectronicsElectronics TechnologyElectronics Technology

Landon Johnson

Encoding, Decoding, and

Seven-Segment Displays


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Encoder/Decoder CompetenciesEncoder/Decoder Competencies

52. Given four different input combinations to a 10 line to 4 lineencoder, the student will state the output combinations with100% accuracy.

53. Given four different input combinations for a 4 line to 10line decoder, the student will state the output combinations

with 100% accuracy.


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Encoder/Decoder VocabularyEncoder/Decoder Vocabulary

ENCODER- a digital circuit that produces abinary output code depending on which of itsinputs are activated.

DECODER- a digital circuit that converts aninput binary code into a single numericoutput.


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ENCODERS AND DECODERSENCODERS AND DECODERS

A0

A1

A2

A3

A4A

5

A6

A7

ENCODER

O0

O1

O2

A0

A1

A2

O0

O1

O2

O3

O4O

5

O6

O7

DECODER

ONLY ONE INPUTONLY ONE INPUT

ACTIVATED AT A TIMEACTIVATED AT A TIME

BINARY CODE OUTPUTBINARY CODE OUTPUT

BINARY CODE INPUTBINARY CODE INPUT

ONLY ONE OUTPUTONLY ONE OUTPUT

ACTIVATED AT A TIMEACTIVATED AT A TIME


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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 4 9 2 6

8421 BCD coded number 0100 1001 0010 0110


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ELECTRONIC ENCODER -

DECIMALTO BCD

0

Decimal

to

BCD

Encoder

BCD output

Decimal input0 0 0 0

5

0 1 0 1

7

0 1 1 1

3

0 0 1 1

Encoders are available in IC form.

This encoder translates from decimal

input to BCD output.


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10 line to 4 line Encoder10 line to 4 line Encoder


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ENCODER

1248

DECIMAL BINARY (BCD)

9 5V

8 5V

7 5V

6 5V

5 5V

4 5V3 5V

2 5V

1 5V

74147I9I8I7I6I5I4

I3I2I1

A0A1A2A3

10 line to 4 line Encoder10 line to 4 line Encoder


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0

1

2

3

4

5

6

7

8

9

DECODER

BINARY (BCD)

DECIMAL

1 0V

2 0V

4 0V

8 0V

74LS42

A3A2A1A0

9876543210

4 line to 10 line Decoder4 line to 10 line Decoder


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BCD-to-

7-Segment

Decoder/

Driver

DECODERS: BCD TO

7-SEGMENT DECODER/DRIVER

BCD input

0 0 0 0

Decimal outputLED

0 0 0 10 0 1 00 0 1 10 1 0 0

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.


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BCD-to-

7-Segment

Decoder/Driver

BCD inputDecimal output

0011

?

Q #1- What is the decimal output from the decoder thatappears on the 7-segment display?

Answer: 3


0000

Answer: 0


1 0 0 1

Answer: 9


Answer: 7

0 1 1 1


Answer: 6

0 1 1 0

TEST


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BCD-TO-SEVEN SEGMENT DECODER DRIVER

5V

abcdef g .

V+

74LS47A3A2A1A0

testRBI

gfedcba

RBO


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TEST

A0

A1

A2

A3

A4

A5

A6

A7

ENCODER

O0

O1

O2

O3

A8

A9

I PUT 3

A1=1

A4=1

A6=1

A8=1


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TEST

A0

A1

A2

O0

O1

O2

O3

O4

O5

O6

O7

DECODER

O8

O9

A3

A3 A2 A1 A0

0 0 0 00 1 0 1

0 1 1 1

1 0 0 1


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TEST

ANSWERTHE FOLLOWING QUESTIONS WITH ONE ORMOREOF THESE WORDS: M X, DEM X, 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. MUXD. 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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