SAN3010

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PAGE

2

LOC

OBJ

LINE

SOURCE

0088

51

Disable equ

88H

52

53

; #############################################################

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; Main program: load Accumulator with key code (see below) and

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;

call subroutine "Key_In"

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4000

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Org

04000H

; set start address of program

4000 758160

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mov

SP,#060H

; set stack pointer

4003 00

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HS_OK:

NOP

; make sure that at this point

60

; the SA253x has been off-hook

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; for >20ms

4004 740A

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Ld_Key: mov

a,#10

; load keycode, here key "0"

4006 12400B

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Call

Key_in

; execute keystroke

4009 80FE

64

jmp

$

; end of main program, exit at

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; this point or continue with

66

; next key entry

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; rem.: add additional delay when

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; cascading memories (s. Delay7:)

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; #############################################################

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; *************************************************************

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; Subroutine Key_in

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; *************************************************************

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; this subroutine executes a key entry to the SA253x

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; the corresponding key code(0...31) must be loaded in the accu

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; see table at label:"scantbl"

for key codes

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; affected Registers:

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;

A,B,R1,R2,R3,R5,R6,R7,DPTR

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80

400B 12405C

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Key_in: call

getScTb

; preload Reg5..7 with scan table

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; Row X: variable in Reg5

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; Row Y: variable in Reg6

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; Col X: variable in Reg7

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400E 7B00

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Exe_Key:mov

R3,#0

; clear loop counter

4010 7480

87

mov

a,#ForceLO

; force R1 low

4012 F590

88

mov

P1,A

4014 3097FD

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sync:

jnb

P1.7, $

; make sure, C1= C2 = low

4017 2097FD

90

jb

P1.7, $

; wait for rising edge C1 or C2

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; = trigger for asynch. timing

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93

;- Delay 1:wait 71.5 us = 66 machine cycles and force RowX high

401A 791F

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delay1: mov

R1,#31

; 1 cycle

401C D9FE

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djnz

R1,$

; 2 cycles; #Loops=(66-4)/2 =31

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401E 7490

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SCAN1:

mov

A,#ForceHi

; 1 cycle

4020 4D

98

orl

A,R5

; 1 cycle

4021 F590

99

mov

P1,A

; 1 cycle

100

101

;--------------------------------------------------------------

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;Delay2:wait 107.25us= 99 machine cycles +disable all rows/cols

4023 7930

103

delay2: mov

R1,#48

; 1 cycle

4025 D9FE

104

djnz

R1,$

; 2 cycles; #Loops =(99-3)/2 = 48

4027 7488

105

mov

A,#Disable

; 1 cycle