 2000 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA

Appnote 49

www.infineon.com/opto • 1-888-Infineon (1-888-463-4636)

OSRAM Opto Semiconductors GmbH & Co. OHG • Regensburg, Germany

www.osram-os.com • +49-941-202-7178

6

May 31, 2000-14

0044 F8

61

MOV

R0,A

;Pointer in the RAM buffer

0045 7600

62

MOV

@R0,#00H

;Displayed so far

0047 7820

63

MOV

R0,#20H

;Beginning of the RAM buffer

0049 E6

64

MOV

A,@R0

;Read the character

004A C0E0

65

PUSH

ACC

;Save it

004C 08

66

AGAIN:

INC

R0

;Next location in RAM buffer

004D E6

67

MOV

A,@R0

;Read the next character

004E 18

68

DEC

R0

;Back to first character

004F F6

69

MOV

@R0,A

;Replace with second character

0050 08

70

INC

R0

;Process repeats

0051 DDF9

71

DJNZ

R5,AGAIN

;Moving character backwards

0053 08

72

INC

R0

0054 7600

73

MOV

@R0,#00H

;End of character buffer

0056 D0E0

74

POP

ACC

;Restore character

0058 7820

75

CONT0:

MOV

R0,#20H

;Beginning of character buffer

005A E9

76

MOV

A,R1

;Check if end of character buffer

005B 6087

77

JZ

OPTS

005D 120071

78

CALL

OUTC

0060 C2AF

79

CLR

IEN0.7

;Disable interrupt

0062 1200A4

80

CALL

WAITA

;Before delay

0065 75A881

81

MOV

IEN0,#81H

;Enable interrupt

0068 D288

82

SETB

IT0

;INT0 control bit

006A 012D

83

AJMP

SHIF

84

85

;

86

;

87

;

88

006C A3

89

NEXTC:

INC

DPTR

006D 7400

90

MOV

A,#0

006F 93

91

MOVC

A,@A+DPTR

;Move the character to Acc.

0070 22

92

RET

93

94

;

95

;

96

;

97

;

98

;

99

0071 C0E0

100

OUTC:

PUSH

ACC

0073 C082

101

PUSH

DPL

0075 C083

102

PUSH

DPH

0077 7A04

103

MOV

R2,#4

;For four digits (0 to 3) in a chip

0079 901004

104

MOV

DPTR,#1004H

;Digit 0 in first display chip

007C 120098

105

CALL

OUTC0

007F 902004

106

MOV

DPTR,#2004H

;Digit 0 in second display chip

0082 120098

107

CALL

OUTC0

0085 904004

108

MOV

DPTR,#4004H

;Digit 0 in third display chip

0088 120098

109

CALL

OUTC0

008B 908004

110

MOV

DPTR,#8004H

;Digit 0 in fourth display chip

008E 120098

111

CALL

OUTCO

0091 D083

112

POP

DPH

0093 0082

113

POP

DPL

0095 D0E0

114

POP

ACC

0097 22

115

RET

116

117

;

118

;

119

;

120

;

121

;

122

0098 E6

123

OUTC0:

MOV

A,@R0

The routine moves a character of the message to ACC.

This routine displays and moves a character over the four digits of

the PD2435 and then repeats for the next display chip and so on.

This is a nested subroutine. It moves a nonzero hex value (ASCII)

from left to right of the four digit display.