SAN3010

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MCS-51 MACRO ASSEMBLER

KEY

09/09/96

PAGE

1

LOC

OBJ

LINE

SOURCE

1

; (c) Austria Mikro Systeme International AG AMS

2

; J.Janisch

/ telecom applications

3

; Program name:

KEY.ASM

4

; Version:

A01

5

; Date:

1996-09-09

6

; Author:

J.Janisch / Telecom Applications

7

;

8

; User program for 8051 interface to SA253x for key entry via

9

;

microcontroller

10

; Application Note AN3010

11

; Program code is at Address 4000 HEX

12

;

13

; Reference for calculations:

14

; Clock Frequency of Microcontroller (80C31) = 11.0592 MHz

15

;

--> 1 machine cycle = 12 clock cycles = 1.085 us

16

;

17

; Decoder Logic:

18

; Port1:

19

; P1.7 : active low input; detects rising edge of C1 OR C2

20

;

should be set high by any output command to port 1

21

; P1.6 : not used

22

; P1.5 : not used

23

; P1.4 : forces selected row/column high or low

24

; P1.3 : when high, disables all rows/columns (high Z)

25

; P1.2 : row / column selector

MSB

26

; P1.1 : row / column selector

27

; P1.0 : row / column selector

LSB

28

;

29

;

P1.2 P1.1 P1.0

select:

30

;

0

0

0

row 1

31

;

0

0

1

row 2

32

;

0

1

0

row 3

33

;

0

1

1

row 4

34

;

1

0

0

column 1

35

;

1

0

1

column 2

36

;

1

1

0

column 3

37

;

1

1

1

column 4

38

;

39

40

0000

41

Row1

equ

0

0001

42

Row2

equ

1

0002

43

Row3

equ

2

0003

44

Row4

equ

3

0004

45

Col1

equ

4

0005

46

Col2

equ

5

0006

47

Col3

equ

6

0007

48

Col4

equ

7

0090

49

ForceHi equ

90H

0080

50

ForceLo equ

80H

13 Appendix C: Sample Software listing