;****************************************************
;timer0.asm
;	timer0 overflow interrupt example
;   execute via "Auto Step"(Alt-F5)
;	Celio G.  MC404	Sept 2012
;   Atuakizado em 
;****************************************************
.nolist
.include "m88def.inc"
.list
.set MAXINT = 16   ; maximo numero de interruppcoes
.def	temp	=r16
start:
	rjmp	RESET	;reset handle

.org	0x10
    rjmp timer0		; go to timer0 overflow counter interrupt routine

RESET:
	clr xl			; will use X as an interrupt counter
	clr xh
	ldi temp,1		;  no Atmega88 este registrador está fora do espaço de E/S!
	sts TIMSK0,temp	; enable timer0 overflow interrupt (p.102 datasheet)
	ldi temp,1			; set prescalong: 1= no prescaling 5=  CK/1024 pre-scaling (p 102-103 datasheet)
	out TCCR0B,temp	; also starts timer0 counting
	                ;out SMCR,temp		 SMCR=1 selects idle mode sleep and enables sleep (p 37-38 datasheet)
	sei				; Global Interrupt enable

l0:					;sleep enter idle mode sleep: wait for interrupt
	cpi xl, MAXINT	        ; vamos contar somente MAXINT interruppcoes
	brne l0			; 
done: 				; yes stop timer0
    clr r17
    out TCCR0B,r17	; stop timer0 counter: no more interrupts 
	rjmp PC

;**************************************************************
					; timer0 overflow interrupt routine
timer0:	
    push temp		; save into stack
    in temp,SREG	; get SREG
	push temp		; and save it in stack			
    adiw x,1
	pop temp		; get SREG from stack
	out SREG, temp	; restore it
	pop temp		; now restore r
    reti
;**************************************************************