Intel mcs-48 manual Adding Output for KEYBOARD/DISPLAY Scanning

Models: mcs-48

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APPLICATION EXAMPLES

+5V GND

 

Vee

VSS

18

 

15

 

P10

DISPLAY

 

Pl1

19

-

XTAll

P12

20

AND/OR

 

 

 

 

KEYBOARD

 

 

Pt3

21

_ 16

 

ARRAY

XTAl2

P14

22

 

 

 

P15

23

 

17 __

P16

24

 

P17

25

 

-

RESET

 

 

 

 

8049

.20...,2;::-6--- I A

 

8049

 

P21

27

14LSl64

8748

P22

1

1141

8021"

P23

,2

 

 

>

 

8035

 

 

 

CLR

 

8039

 

 

 

8022*

 

'-t---+1

 

 

 

 

 

POQ

12

 

This is most useful when the outputs of the 74LS164 eight-bit shift register will be used to scan a display and/or keyboard. In this case an ANLD P7, A with A = OFFH can be used to load the initial "1" and an ANLD P6, Awith A =OFEH can be used to move it down the shift register.

13

POt

13

 

P02

14

 

_ T1

 

 

POl

15

 

 

P04

16

 

 

P05

17

 

 

POG

18

'PINNUMBERS ARE DIFFERENT FOR 8021, 8022

 

P07 19

ADDING OUTPUT FOR KEYBOARD/DISPLAY SCANNING

5-16

Page 127
Image 127
Intel mcs-48 manual Adding Output for KEYBOARD/DISPLAY Scanning