APPLICATION EXAMPLES

+5V GNo

-2

b26 L

Vee VOD Vss

XTAL 1

-3

XTAl2

-4

RESET

8049

-7EA8048 8748

- ss 8021" 8035

8039

8022·

1 _ TO

39

PlO

27

Pl1

28

P12

29

 

 

PT3

30

W

EO

.14

31

 

El

P15

32

 

E2

PT6

33

 

E3

.17

34

 

E4

 

 

 

E5

P20

21

 

E6

 

~-+---IA

74150

P21

22

E7

(24)

P22

23

E8

P23

17:--+---1 C

 

E9

~-+='-----Io

 

24

 

 

P24

35

 

El0

P25

36

 

Ell

P26

37

 

E12

P27

38

 

E13

 

 

 

E14

DBO 12

 

E15

DBT

13

 

 

Normal 1/0 port is used to select an address for the 16-to-1 multiplexer. The output of the multiplexer is brought into a test input. Eight inputs could be added with a 74LS151 8-to-1 multiplexer using the same structure.

Nota: If external program memory Is being addressed, use P24-P27 instead of P20-P23.

Tl -6iNT

ADDING 16 INPUT LINES

DB2'4

DB3 15

DB4 16

 

DBS 11

 

DBB 18

 

DB7 19

'PINNUMBERS ARE DIFFERENT FOR 8021. 8022

 

 

+5V

GNo

 

 

 

 

 

 

 

 

b26 L

 

 

 

 

 

 

 

 

Vee

VOD Vss

PTO

27

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

Pl1

28

 

 

 

 

- XTAlT

 

 

 

 

 

 

P12

29

 

 

 

 

 

3

 

 

PT3

30

 

 

 

 

 

 

 

P14

31

 

 

 

 

- XTAl2

 

 

 

 

 

 

P15

32

 

 

 

 

 

4

 

 

P16

33

 

 

 

 

 

 

 

P17

34

 

 

 

 

- RESET

 

 

 

 

 

 

 

 

 

 

 

 

-

7

 

 

PlO

21

 

 

 

 

EA

 

P21

22

 

 

 

 

 

8049

 

 

 

 

 

 

P22

23

 

 

 

 

 

 

ss

8048

.23

24

 

 

 

 

 

 

8748

P24

35

 

 

 

 

 

 

 

 

P25

36

 

 

 

 

 

 

 

 

P26

37

 

 

 

 

 

 

 

 

P27

38

 

 

 

 

 

1

 

 

DBD 12

14 60

 

6a

- TO

 

 

39

 

 

DBT

13

13

60

 

sa

- Tl

 

oB2 14

11

40

74LS174

4a

 

6

 

 

0B3 15

6

3D

(16)

3a

 

 

 

 

-

iNf

 

oB4 16

 

20

 

2a

 

 

DBS 17

 

10

ClK

la

 

 

 

 

DBB 18

 

 

 

 

 

 

 

 

DB7 19

 

 

 

 

The latch can be loaded with the OUTL instruction. After the latch is loaded the BUS output state can be modified with the ANL BUS, # DATA and the ORL BUS, # DATA. The OUTL generates a WR strobe; ANL and ORL do not. In this configuration DBo-DB7 will be momentarily disturbed while the external latch is loaded.

ADDING 6 OUTPUT LINES

5·15

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Image 126
Intel mcs-48 manual Application Examples, ·15