example1

main:
; Load stack register	 in two steps (4 commands) Note: When you are loading a 
LDI R16, HIGH(RAMEND)				; load UPPER byte 1-byte register from a 2-byte word, first
OUT SPH,R16								  ; to stack pointer  you load either the HIGH([word])
LDI R16,LOW(RAMEND)					; Lower byte  or the LOW([word]), second
OUT SPL,R16			            ; to stack pointer   ;OUT SPL,R16 writes R16 to SPL. 

; Define directions for port pins
ldi r16,(1<<PB0)|(1<<PB1)|(1<<PB2)|(1<<PB3)|(1<<PB4) ;load to R16  all ports set to output   0001 1111
out DDRB,R16          ; set direction .  OUT DDRB,R16 writes R16 to DDRB.  0x1F=31

ldi R16,(1<<CS01)     ; CS01 = 1 in def    clock counter with I/O clock/8  and WGM2   live in   TCCR0B
out TCCR0B,R16
		    ; =  One  (1)  shifted by 0 bit  = 1
ldi R16,(1<<WGM01)    ; WGM01 = 1  in def table ;WGM[2:0] = 0x2 sets CTC mode.Clear Timer on Compare Match (CTC) mode; COM0cn =0 | do not control pins with compare match.
out TCCR0A,R16        ;WGM1/WGM0  live in  TCCR0A    

ldi R16,(1<<OCIE0A)   ; OCIE0A = 4 in def Output Compare_0 interrupt enable  take a 1 and shif it by 4 (bit4   in TIMSK )
out TIMSK,R16			    ;put in the timsk register   OCIE0A = 4 in tne at85def.inc file

ldi R16,125		
out OCR0A,R16		; OCR0A = 125  =  1ms  =  125/125000Hz

sei		      ; set enable interrupt on the chip globally

loop:
rjmp loop	  ; when TCNT0 = 7D   out |2 clock cycles every F11 * 4 times  /= 8