System Digital

Encoder, Decoder, andContoh Penerapanya

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 0

A 1

A 2

A 3

A 4

A 5

A 6

A 7

ENCODER

O 0

O 1

O 2

A 0

A 1

A 2

O 0

O 1

O 2

O 3

O 4

O 5

O 6

O 7

DECODER

Hanya Satu masukan yang aktif pada satu waktuKeluaran berupa kode biner

Masukan berupa kode biner

Hanya satu keluaran yang aktif pada satu waktu

The truth table of 2-to-4 Decoder

2-to-4 Decoder

2-to-4 Decoder

The truth table of 3-to-8 Decoder

A2 A1 A0 D0 D1 D2 D3 D4 D5 D6 D7

0 0 0 1

0 0 1 1

0 1 0 1

0 1 1 1

1 0 0 1

1 0 1 1

1 1 0 1

1 1 1 1

3-to-8 Decoder

3-to-8 Decoder with Enable

2-to-4 Decoder: NAND implementation

Decoder is enabled when E=0 and an output is active if it is 0

2-4 Decoder with 2-input and Enable

Decoder Expansion

Decoder expansion Combine two or more small decoders with enable

inputs to form a larger decoder

3-to-8-line decoder constructed from two 2-to-4-line decoders The MSB is connected to the enable inputs if A2=0, upper is enabled; if A2=1, lower is enabled.

Decoder Expansion

Combining two 2-4 decoders to form one 3-8 decoder using enable switch

The highest bit is used for the enables

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

ELECTRONIC ENCODER -

DECIMAL TO BCD

0

Decimalto

BCDEncoder

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.

10 line to 4 line Encoder

ENCODER1248

DECIMAL BINARY (BCD)

9 5V

8 5V

7 5V

6 5V5 5V

4 5V3 5V

2 5V1 5V

74147I9I8I7I6I5I4I3I2I1

A0A1A2A3

10 line to 4 line Encoder

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 Decoder

BCD-to-7-SegmentDecoder/

Driver

DECODERS: BCD TO 7-SEGMENT DECODER/DRIVER

BCD input

0 0 0 00 0 0 0

Decimal outputLED

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

BCD-to-7-SegmentDecoder/

Driver

BCD inputDecimal output

0 0 1 1

?

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

Answer: 3

Q #2- What is the decimal output from the decoder that appears on the 7-segment display?

0 0 0 0

Answer: 0

Q #3- What is the decimal output from the decoder that appears on the 7-segment display?

1 0 0 1

Answer: 9

Q #4- What is the decimal output from the decoder that appears on the 7-segment display?

Answer: 7

0 1 1 1

Q #5- What is the decimal output from the decoder that appears on the 7-segment display?

Answer: 6

0 1 1 0

TEST

BCD-TO-SEVEN SEGMENT DECODER DRIVER

5V

abcdef g .

V+

74LS47A3A2A1A0

testRBI

gfedcba

RBO

TEST

A 0

A 1

A 2

A 3

A 4

A 5

A 6

A 7

ENCODER

O 0

O 1

O 2

O 3

A 8

A 9

INPUT O3 O2 O1 O0A1=1A4=1A6=1A8=1

TEST

A 0

A 1

A 2

O 0

O 1

O 2

O 3

O 4

O 5

O 6

O 7

DECODER

O 8

O 9

A 3

A3 A2 A1 A0 OUTPUT0 0 0 00 1 0 10 1 1 11 0 0 1

TESTANSWER 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 alsoMUX.