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lcd3.s
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PORTB=$6000
PORTA=$6001
DDRB=$6002
DDRA=$6003
E=%10000000
RW=%01000000
RS=%00100000
.org $8000
reset:
lda #$ff
sta DDRB
sta DDRA
lda #$01 ; clear display
jsr lcd_sendInstruction
lda #$06 ; Left-to-right, shift off
jsr lcd_sendInstruction
lda #$0e ; Display on, cursor on, blink off
jsr lcd_sendInstruction
lda #$38 ; 8-bit mode, 2-lines, 5x8 Font
jsr lcd_sendInstruction
jsr printString
loop:
jmp loop
text: .string "Hello World"
printString:
ldx #0
printChar:
lda text, x
beq done
jsr lcd_sendChar
inx
jmp printChar
done:
rts
lcd_wait:
pha
lda #0
sta DDRB ; PORT B as inputs
lcd_busy:
lda #RW ; read from display
sta PORTA
lda #(RW|E)
sta PORTA
lda PORTB
and #%10000000
bne lcd_busy
lda #0
sta PORTA
lda #$ff
sta DDRB ; PORT B as outputs
pla
rts
lcd_sendInstruction:
jsr lcd_wait
sta PORTB
lda #0
sta PORTA
lda #E
sta PORTA
lda #0
sta PORTA
rts
lcd_sendChar:
jsr lcd_wait
sta PORTB
lda #0
sta PORTA
lda #(E|RS)
sta PORTA
lda #0
sta PORTA
rts
.org $fffc
.word reset
.word $ffff