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4-MULTIPLEXED LCD WITH A STANDARD ST62

How to customise: as long as all frontplane pins belong to the same I/O port, it is possible to

change I/O pin allocations or character coding just by modifying the equates and constant

table definitions located at the beginning of LCD_drv.st6:

– the mask equates selecting all or a subset of the frontplane pins,

– the look-up table for character coding,

– the bit definition equates selecting frontplane pins related to icon segments.

Figure 8. Operations to convert a character code into a frontplane waveform

inversion

charac:

DB

0aah,000h,055h,000h

; display 0

DB

0ffh,0aah,0ffh,0aah

; display 1

DB

0aah,055h,0aah,000h

; display 2

DB

0aah,0aah,0aah,000h

; display 3

DB

0ffh,0aah,000h,0aah

; display 4

DB

0aah,0aah,000h,055h

; display 5

DB

0aah,000h,000h,055h

; display 6

DB

0ffh,0aah,0ffh,000h

; display 7

DB

0aah,000h,000h,000h

; display 8

DB

0aah,0aah,000h,000h

; display 9

DB

0ffh,000h,000h,0aah

; display H

DB

0ffh,0ffh,0aah,0ffh

; display -

DB

0aah,055h,055h,0aah

; display L

DB

0ffh,055h,000h,000h

; display P

DB

0aah,055h,000h,055h

; display E

DB

0ffh,0ffh,0ffh,0ffh

; display ’Blank’

min_dig1I

= 9

LCD_Ph

mod 4 = 0

LCD_Ph

= 4

1

1

1

0

0

0 1 0

0

0

1

0

1

0 0

0

LCD_Ph

≥ 4

1

1

1

0

0

0 1

0

0

0

1

0

0

0 0

0

AND

0

0

0

0

0

1 0

0

previous value of

DR_seg_2

min_dig1

= 9

Step 1

0

0

1

0

0

1 0

0

ADD

new value stored

into DR_seg_2

look-up table defined

in LCD_drv.st6

image variable of

min_dig1

Example with minutes digit 1

; (Bit = 1) <=> pin is a frontplane pin for:

MIN0_SEL EQU

003h

; - digit 0 for minutes

MIN1_SEL EQU

00ch

; - digit 1 for minutes

HR0_SEL

EQU

030h

; - digit 0 for hours

HR1_SEL

EQU

0c0h

; - digit 1 for hours

equates defined in

LCD_drv.st6