LCD

;; (C) David Vajda
;; 2024-12-20
;; LCD - RS232

.include "m8def.inc"

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

ldi r16, 0xff
out DDRB, r16

rcall lcd_init

ldi r16, HIGH (25)
out UBRRH, r16
ldi r16, LOW (25)
out UBRRL, r16

ldi r16, (1 << URSEL) | (1 << UCSZ1) | (1 << UCSZ0)
out UCSRC, r16
ldi r16, (1 << RXEN)
out UCSRB, r16

urecieve:
sbis UCSRA, RXC
rjmp urecieve
in r16, UDR
rcall lcd_data
rjmp urecieve


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

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

lcd_init:
push r16
rcall sleep
ldi r16, 0x03
out PORTB, r16
rcall sleep
ldi r16, 0x03
out PORTB, r16
rcall sleep
ldi r16, 0x03
out PORTB, r16
ldi r16, 0x02
rcall lcd_cmd
ldi r16, 0x20
rcall lcd_cmd
ldi r16, 0x01
rcall lcd_cmd
ldi r16, 0x02
rcall lcd_cmd
pop r16
ret

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

lcd_cmd:
push r17
push r16
mov r17, r16
swap r16
andi r16, 0x0f
andi r17, 0x0f
out PORTB, r16
rcall lcd_enable
out PORTB, r17
rcall lcd_enable
rcall sleep
pop r16
pop r17
ret