m820241130007LCD.asm

; (C) David Vajda
; 2024-11-30
; LCD HD44780 - Atmega 8

.include "m8def.inc"

ldi r16, HIGH (RAMEND)
out SPH, r16
ldi r16, LOW (RAMEND)
out SPL, r16

ldi r16, 0xff
out DDRD, r16

rcall lcd_init
ldi r16, ' '
rcall lcd_data
ldi r16, 'w'
rcall lcd_data
ldi r16, 'w'
rcall lcd_data
ldi r16, 'w'
rcall lcd_data
ldi r16, '.'
rcall lcd_data
ldi r16, 'y'
rcall lcd_data
ldi r16, 'u'
rcall lcd_data
ldi r16, 'n'
rcall lcd_data
ldi r16, '7'
rcall lcd_data
ldi r16, 'x'
rcall lcd_data
ldi r16, '.'
rcall lcd_data
ldi r16, 'd'
rcall lcd_data
ldi r16, 'e'
rcall lcd_data
end: rjmp end

sleep:
push r16
ldi r16, 0xff
sleep_loop1:
dec r16
brne sleep_loop1
pop r16
ret

lcd_enable:
sbi PORTD, 5
nop
nop
nop
cbi PORTD, 5
ret

lcd_init:
rcall sleep
ldi r16, 0x03
out PORTD, r16
rcall sleep
ldi r16, 0x03
out PORTD, r16
rcall sleep
ldi r16, 0x03
out PORTD, r16
rcall sleep
ldi r16, 0x02
rcall lcd_cmd
ldi r16, 0x20
rcall lcd_cmd
ldi r16, 0x01
rcall lcd_cmd
ldi r16, 0x02
rcall lcd_cmd
ret

lcd_data:
mov r17, r16
swap r16
andi r16, 0x0f
andi r17, 0x0f
ori r16, 0b00010000
ori r17, 0b00010000
out PORTD, r16
rcall lcd_enable
out  PORTD, r17
rcall lcd_enable
rcall sleep
ret

lcd_cmd:
mov r17, r16
swap r16
andi r16, 0x0f
andi r17, 0x0f
out PORTD, r16
rcall lcd_enable
out PORTD, r17
rcall lcd_enable
rcall sleep
ret