# Encoders Module M9.3 Section 6.3. Encoders Priority Encoders TTL Encoders.

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Encoders Module M9.3 Section 6.3

Encoders Priority Encoders TTL Encoders

Encoders A B I0 I1 I2 I3 4-to-2 Encoder 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 I2 I3 B A

Encoders 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 I2 I3 B A Assume only 1 input can be high at any time. A = I1 # I3 B = I2 # I3 I1 I2 I3 I0 B = I2 # I3 A = I1 # I3

8-to-3 Encoder 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 I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0 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 6, 7, 11, 5, 72, 71, 66, 70; " Switch 1..8 " OUTPUT PINS " Y2..Y0 PIN 37, 36, 35 ISTYPE 'com'; " LED 6..8 EQUATIONS Y2 = I7 # I6 # I5 # I4; Y1 = I7 # I6 # I3 # I2; Y0 = I7 # I5 # I3 # I1; END encoder83

Priority Encoder 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 I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0

Priority Encoder 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 I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0 Y2 = L7 # L6 # L5 # L4 L7 = I7 L6 = !I7 & I6 L5 = !I7 & !I6 & I5 L4 = !I7 & !I6 & !I5 & I4

Priority Encoder 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 I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0 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 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 I0 I1 I2 I3 I4 I5 I6 I7 Y2 Y1 Y0 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, A. Student, 7/15/02' DECLARATIONS " INPUT PINS " I7..I0 PIN 6, 7, 11, 5, 72, 71, 66, 70; " Switch 1..8 " OUTPUT PINS " Y2..Y0 PIN 37, 36, 35 ISTYPE 'com'; " LED 6..8 VALID PIN 44;" LED 1 " VALID = 1 for valid binary output " INTERMEDIATE NODES " L7..L0 NODE ISTYPE 'com'; " internal vector

pencoder.abl (cont’d) EQUATIONS 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; Y2 = L7 # L6 # L5 # L4; Y1 = L7 # L6 # L3 # L2; Y0 = L7 # L5 # L3 # L1; END pencoder83

TTL Encoder 1 2 3 4 5 6 7 89 10 11 12 13 14 15 16 GND Vcc 1 2 3 4 5 6 7 A2 A1 E1 E0 GS 0 A0 74LS148 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 EI 0 1 2 3 4 5 6 7 A2 A1 A0 GS EO Priority Encoder

68000 Interrupt Logic Peripheral 74148 Encoder 74138 Decoder IP0 IP1 IP2 A0 A1 A2 IRQA 68000 Data Bus IRQ

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