Assembly: simple delay

;********************************************** 

;3/13/2019

;Blink LED 

;********************************************** 

.include "ATxmega128A1Udef.inc"

.equ BIT0 = 0x01

.org 0x0

rjmp MAIN

MAIN:

ldi R16, BIT0

sts PORTC_DIRSET, R16

sts PORTA_DIRCLR, R16

sts PORTC_OUT, R16

POLLING:

lds R16, PORTA_IN

andi r16, BIT0

cpi r16, BIT0

brne POLLING

ldi r19, 0x01

rcall DELAY_X_10MS

sts PORTC_OUTTGL, R16

rjmp POLLING

;****************************************** 

;Delays by x10 ms 

;******************************************

DELAY_X_10MS: 

cpi r19, 0 ;5 passed in from LOOP 

brne LOOP3 ;if not 0, go again 

ret 

LOOP3: 

rcall DELAY_10MS 

dec r19 

brne LOOP3 

ret 

;****************************************** 

;delays by 10 ms 

;****************************************** 

DELAY_10MS: 

ldi r17, 0x16 ;outer loop @ 1B

LOOP1: 

dec r17 

brne START_COUNT 

ret

START_COUNT: 

;ldi r18, 0xFF ;inner loop @ FF 

ldi r18, 0x02

LOOP2: 

dec r18 

brne LOOP2 

rjmp LOOP1