© 1995 Microchip Technology Inc.

DS70010I-page 5

AY0438

;The DP are not connected, but can be connected to seg8, 16, 24 & 32.

;For each digit, the segments are connected as:

;

Seg A --> seg(8*n + 1)

;

Seg B --> seg(8*n + 2)

;

Seg C --> seg(8*n + 3)

;

Seg D --> seg(8*n + 4)

;

Seg E --> seg(8*n + 5)

;

Seg F --> seg(8*n + 6)

;

Seg G --> seg(8*n + 7)

;where n = 0, 1, 2 and 3 for MSD, 3rdSD, 2ndSD and LSD respectively.

;The firmware uses the values in registers:

;

MSD, THRDSD, SCNDSD and LSD

to determine the values to be

;pulsed to the AY0438.

;In this example, a pushbutton connected to PORTB bit 7

;is checked periodically to see if it has been pressed. If so,

;the LCD values in locations MSD to LSD are updated.

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

list p=16c71,f=inhx8m

;

;

MSD

equ

0x20

THRDSD

equ

0x21

SCNDSD

equ

0x22

LSD

equ

0x23

count

equ

0x24

temp

equ

0x25

PORTB

equ

0x06

#define CLK

PORTB,0

#define DATAIN

PORTB,1

#define LOAD

PORTB,2

#define UPDATELCD PORTB,7

w

equ

0

STATUS

equ

0x03

C

equ

0

RP0

equ

5

OPTION

equ

0x81

RBPU

equ

7

PCL

equ

0x02

PCLATH

equ

0x0A

;

;

org

0

goto

start

org

0x10

;

;This DecodeValue table must reside in page 0 for this program to work

;

DecodeValue

addwf

PCL

retlw

B'00111111'

;decode for 0

retlw

B'00000110'

;decode for 1

retlw

B'01011011'

;decode for 2

retlw

B'01001111'

;decode for 3

retlw

B'01100110'

;decode for 4

retlw

B'01101101'

;decode for 5