encoder & decoder ppt
TRANSCRIPT
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Alpha Breathing
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Evocation
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ENCODER & DECODER
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INTRODUCTION
ENCODER- a digital circuit that producesa 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.
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ENCODERS AND DECODERS
REPRESENTATION
A0
A1
A2
A3
A4
A5
A6
A7
ENCODER
O0
O1
O2
A0
A1
A2
O0
O1
O2
O3
O4
O5
O6
O7
DECODER
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THE 8421 BCD CODE
BCD stands for Binary-Coded Decimal.
A BCD number is a four-bit binary group thatrepresents 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 -
DECIMAL TO 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 Encoder
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ENCODER
1248DECIMAL BINARY (BCD)
95V
85V
7 5V
65V
5 5V
4 5V3 5V
2 5V
15V
74147I9I8I7I6I5I4
I3I2I1
A0A1A2A3
10 line to 4 line Encoder
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Decoder
Accepts a value and decodes it
Output corresponds to value of ninputs
Consists of: Inputs (n)
Outputs (2n, numbered from 02n- 1)
Selectors / Enable (active high or active low)
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The truth table of 2-to-4
Decoder
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2-to-4 Decoder
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2-to-4 Decoder
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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
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3-to-8 Decoder
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3-to-8 Decoder with Enable
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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.
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Decoder Expansion
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Combining two 2-4 decoders to form
one 3-8 decoder using enable switch
The highest bit is used for the enables
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How about 4-16 decoder
Use how many 3-8 decoder?
Use how many 2-4 decoder?
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Encoders
Perform the inverse operation of a
decoder
2n(or less) input lines and n output lines
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Encoders
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Encoders with OR gates
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Encoders
Perform the inverse operation of a decoder
2n(or less) input lines and n output lines
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Accepts multiple values and encodes them
Works when more than one input is active
Consists of:
Inputs (2n)
Outputs
when more than one output is active, setsoutput to correspond to highest input
V (indicates whether any of the inputs areactive)
Selectors / Enable (active high or active low)
Priority Encoder
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D3 D2 D1 D0 A1 A0 V
0 0 0 0 x X 0
0 0 0 1 0 0 1
0 0 1 0 0 1 1
0 0 1 1 0 1 1
0 1 0 0 1 0 1
0 1 0 1 1 0 1
0 1 1 0 1 0 1
0 1 1 1 1 0 1
1 0 0 0 1 1 1
1 0 0 1 1 1 1
1 0 1 0 1 1 1
1 0 1 1 1 1 1
1 1 0 0 1 1 1
1 1 0 1 1 1 1
1 1 1 0 1 1 1
1 1 1 1 1 1 1
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Priority Encoder
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Puzzles
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Mind Map Encoder and Decoder
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Encoder Applications
Applications
Priority Encoder
Mind Map Encoder and Decoder
Decoder2 to 4 line
decoder
3 to 8 line
Decoder
Decimal BCD
to encoder
TruthtableBlockdiagram Logicdiagram
Code
conversion
Octal to binary
encoder
Hexadecimal to
binary encoder
Counter system
A to D counter
Display system
Block
diagramTruth
table
Logic
diagram
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Summary
Encoders & Decoders
Truth table
K-Map
Logic Diagram
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