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PORTB = $6000
PORTA = $6001
DDRB = $6002
DDRA = $6003
E = %10000000
RW = %01000000
RS = %00100000
.org #$f800
reset:
ldx #$FF ; initialize call stack to $1FF
txs
lda #%11111111 ; set output on all pins of PORTB
sta DDRB
lda #%11100000 ; set output on LCD control pins of PORTA
sta DDRA
lda #%00111000 ; set 8-bit, 2-line display, 5x8 font
jsr lcd_send_command
lda #%00001110 ; display on, cursor on, no blink
jsr lcd_send_command
lda #%00000001 ; clear display
jsr lcd_send_command
lda #%00000010 ; return home
jsr lcd_send_command
lda #%00000110 ; set entry mode: increment, no shift
jsr lcd_send_command
lda #'6' ; data to send
jsr lcd_send_data
lda #'5' ; data to send
jsr lcd_send_data
lda #'0' ; data to send
jsr lcd_send_data
lda #'2' ; data to send
jsr lcd_send_data
term:
jmp term
lcd_send_command:
sta PORTB
lda #$0 ; clear RS/RW/E
sta PORTA
lda #E ; clear RS/RW, set E, send instruction
sta PORTA
lda #$0 ; clear RS/RW/E
sta PORTA
rts
lcd_send_data:
sta PORTB ; data to send to port B
lda #RS ; clear RW, E, set RS for data
sta PORTA
lda #( E | RS ) ; clear RW, set E/RS, send data
sta PORTA
lda #RS ; clear RS, E, keep RS
sta PORTA
rts
.org #$fffc
.word reset
.word $0000
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