Encoders

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# Encoders - PowerPoint PPT Presentation

Encoders. Lecture L6.11 Section 6.4. Encoders. Encoders Priority Encoders TTL Encoders. I0. 4-to-2 . I1. A . Encoder . I2. B . I3. Encoders. I0 I1 I2 I3 B A. 1 0 0 0 0 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 1. I0. I1. A = I1 # I3. I2.

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### Encoders

Lecture L6.11

Section 6.4

Encoders
• Encoders
• Priority Encoders
• TTL Encoders

I0

4-to-2

I1

A

Encoder

I2

B

I3

Encoders

I0 I1 I2 I3 B A

1 0 0 0 0 0

0 1 0 0 0 1

0 0 1 0 1 0

0 0 0 1 1 1

I0

I1

A = I1 # I3

I2

B = I2 # I3

I3

Encoders

Assume only 1 input

can be high at any time.

I0 I1 I2 I3 B A

1 0 0 0 0 0

0 1 0 0 0 1

0 0 1 0 1 0

0 0 0 1 1 1

A = I1 # I3

B = I2 # I3

I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0

1 0 0 0 0 0 0 0 0 0 0

0 1 0 0 0 0 0 0 0 0 1

0 0 1 0 0 0 0 0 0 1 0

0 0 0 1 0 0 0 0 0 1 1

0 0 0 0 1 0 0 0 1 0 0

0 0 0 0 0 1 0 0 1 0 1

0 0 0 0 0 0 1 0 1 1 0

0 0 0 0 0 0 0 1 1 1 1

8-to-3 Encoder

Y2 = I7 # I6 # I5 # I4

Y1 = I7 # I6 # I3 # I2

Y0 = I7 # I5 # I3 # I1

encoder.abl

MODULE encoder83

TITLE 'Encoder, D. Hanna, 7/15/02'

DECLARATIONS

" INPUT PINS "

I7..I0 PIN 11, 7, 6, 5, 4, 3, 2, 1; " Switch 1..8

" OUTPUT PINS "

Y2..Y0 PIN 41, 43, 44 ISTYPE 'com'; " LED 14..16

EQUATIONS

Y2 = I7 # I6 # I5 # I4;

Y1 = I7 # I6 # I3 # I2;

Y0 = I7 # I5 # I3 # I1;

END encoder83

Priority Encoder

I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0

1 0 0 0 0 0 0 0 0 0 0

X 1 0 0 0 0 0 0 0 0 1

X X 1 0 0 0 0 0 0 1 0

X X X 1 0 0 0 0 0 1 1

X X X X 1 0 0 0 1 0 0

X X X X X 1 0 0 1 0 1

X X X X X X 1 0 1 1 0

X X X X X X X 1 1 1 1

Priority Encoder

I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0

1 0 0 0 0 0 0 0 0 0 0

X 1 0 0 0 0 0 0 0 0 1

X X 1 0 0 0 0 0 0 1 0

X X X 1 0 0 0 0 0 1 1

X X X X 1 0 0 0 1 0 0

X X X X X 1 0 0 1 0 1

X X X X X X 1 0 1 1 0

X X X X X X X 1 1 1 1

Y2 = L7

# L6

# L5

# L4

L7 = I7

L6 = !I7 & I6

L5 = !I7 & !I6 & I5

L4 = !I7 & !I6 & !I5 & I4

Priority Encoder

I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0

1 0 0 0 0 0 0 0 0 0 0

X 1 0 0 0 0 0 0 0 0 1

X X 1 0 0 0 0 0 0 1 0

X X X 1 0 0 0 0 0 1 1

X X X X 1 0 0 0 1 0 0

X X X X X 1 0 0 1 0 1

X X X X X X 1 0 1 1 0

X X X X X X X 1 1 1 1

Y1 = L7

# L6

# L3

# L2

L7 = I7

L6 = !I7 & I6

L3 = !I7 & !I6 & !I5 & !I4 & I3

L2 = !I7 & !I6 & !I5 & !I4 & !I3 & I2

Priority Encoder

I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0

1 0 0 0 0 0 0 0 0 0 0

X 1 0 0 0 0 0 0 0 0 1

X X 1 0 0 0 0 0 0 1 0

X X X 1 0 0 0 0 0 1 1

X X X X 1 0 0 0 1 0 0

X X X X X 1 0 0 1 0 1

X X X X X X 1 0 1 1 0

X X X X X X X 1 1 1 1

Y0 = L7

# L5

# L3

# L1

L7 = I7

L5 = !I7 & !I6 & I5

L3 = !I7 & !I6 & !I5 & !I4 & I3

L1 = !I7 & !I6 & !I5 & !I4 & !I3 & !I2 & I1

pencoder.abl

MODULE pencoder83

TITLE 'Priority Encoder'

DECLARATIONS

" INPUT PINS "

I0..I7 PIN 11, 7, 6, 5, 4, 3, 2, 1; " Switch 1..8

" OUTPUT PINS "

Y2..Y0 PIN 41, 43, 44 ISTYPE 'com'; " LED 14..16

VALID PIN 35; " LED 9

" VALID = 1 for valid binary output

pencoder.abl (cont’d)

" Definitions "

L7 = I7;

L6 = !I7 & I6;

L5 = !I7 & !I6 & I5;

L4 = !I7 & !I6 & !I5 & I4;

L3 = !I7 & !I6 & !I5 & !I4 & I3;

L2 = !I7 & !I6 & !I5 & !I4 & !I3 & I2;

L1 = !I7 & !I6 & !I5 & !I4 & !I3 & !I2 & I1;

EQUATIONS

Y2 = L7 # L6 # L5 # L4;

Y1 = L7 # L6 # L3 # L2;

Y0 = L7 # L5 # L3 # L1;

END pencoder83

1

16

Vcc

4

2

15

5

E0

3

14

6

GS

4

13

7

3

5

12

E1

2

6

11

A2

1

7

10

A1

0

8

9

A0

GND

74LS148

TTL Encoder

EI 0 1 2 3 4 5 6 7 A2 A1 A0 GS EO

1 X X X X X X X X 1 1 1 1 1

0 1 1 1 1 1 1 1 1 1 1 1 1 0

0 X X X X X X X 0 0 0 0 0 1

0 X X X X X X 0 1 0 0 1 0 1

0 X X X X X 0 1 1 0 1 0 0 1

0 X X X X 0 1 1 1 0 1 1 0 1

0 X X X 0 1 1 1 1 1 0 0 0 1

0 X X 0 1 1 1 1 1 1 0 1 0 1

0 X 0 1 1 1 1 1 1 1 1 0 0 1

0 0 1 1 1 1 1 1 1 1 1 1 0 1

Priority Encoder

68000 Interrupt Logic

A0

A1

A2

74138

Decoder

68000

IRQA

IP0

IP1

IP2

74148

Encoder

Peripheral

IRQ

Data Bus