ATmega128: FLIP-FLOP de LEDs a várias frequências

; FLIP-FLOP de LEDs a várias frequências dependendo do switch premido

.include <m128def.inc>

.cseg

.org 0x00               ; vector: reset
    jmp main
.org 0x1E               ; vector: interrupcao timer/counter
    jmp subrotina
.org 0x46

init:
    ldi r16, 77             ; carrega 77 em r16
    out OCR0, r16           ; passa 77 para OCR0
    in r16, TIMSK           ; TC0, OCIE0 compara OCR0 e valor contador
    ori r16, 2              ; "ou"
    out TIMSK, r16          ; enable timer output compare interrupt

    ldi r16, 0x08           ; 0b00001000, TC0: modo 2CTC, timer off
    out TCCR0, r16          ; enable timer output compare interrupt

    ldi r17, 0x01           ; 0b00000001
    out DDRC, r17           ; PORTC como saida dados (LED)

    ser r17             ; = ldi r17, 0b11111111, 0xFF
    out PORTC, r17          ; leds apagados

    clr r16             ; = ldi r16,0b00000000, 0x00
    out DDRA, r16           ; PORTA como entrada

    sei                 ; activa interrupcoes globais
    ret                 ; return


subrotina:
    push r17
    in r20, SREG
    dec r18
    brne end_
    in r17, PORTC
    com r17                 ; complementa r17 0PINA 0 25-1-0-1
    out PORTC, r17
    mov r18, r19


end_:
    out SREG,r20
    pop r17
    reti ; return


main:
    ldi r16,0xff            ; stack pointer
    out SPL,r16
    ldi r16,0x10
    out SPH,r16
    call init

; f1 = 100
sw1:
    in r16, PINA
    andi r16, 0x01          ; 0b00000001, verifica SW1
    brne sw2                ; se sw1 nao activo verifica sw2
    ldi r18, 100
    mov r19, r18
    ldi r16, 0x0F           ; 0b00001111, TC0: modo 2CTC, prescaler 1024
    out TCCR0, r16
    jmp sw1             ; volta a ler sw1

; f2 = 50
sw2:
    in r16, PINA
    andi r16, 0x02          ; 0b00000010, verifica SW2
    brne sw3                ; se sw2 nao activo verifica sw3
    ldi r18, 50
    mov r19, r18
    ldi r16, 0x0F           ; 0b00001111, TCO: modo 2CTC,, prescaler 1024
    out TCCR0, r16
    jmp sw1

; f3 = 25
sw3:
    in r16, PINA
    andi r16, 0x04          ; 0b00000100, verifica SW3
    brne sw6                ; se sw2 nao activo verifica sw3
    ldi r18, 25
    mov r19, r18
    ldi r16, 0x0F           ; 0b00001111, TCO: modo 2CTC,, prescaler 1024
    out TCCR0, r16
    jmp sw1

; off
sw6:
    in r16, PINA            ; verifica sw6
    andi r16, 0x20          ; 0b00100000, se sw6 nao activo verifica sw1
    brne sw1
    ldi r16, 0x08           ; 0b00001000, TCO: modo 2CTC,, prescaler 1024
    out TCCR0, r16
    ser r17             ; apagar Led's
    out PORTC, r17
    jmp sw1