31 lines
951 B
NASM
31 lines
951 B
NASM
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.include "atmega1284definition.asm"
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; define constant
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.equ LED_PIN = PD7 ; use PD7 as LED pin
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; start vector
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.org 0x0000
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rjmp main ; jump to main label
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; main program
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main:
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sbi DDRD, LED_PIN ; set LED pin as output
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loop:
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sbic PIND, LED_PIN ; if bit of LED pin is clear, skip next line
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cbi PORTD, LED_PIN ; if 1, turn the LED off
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sbis PIND, LED_PIN ; if bit of LED pin is set, skip next line
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sbi PORTD, LED_PIN ; if 0, light the LED up
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delay_500ms:
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ldi r20, 32 ; set register, r20 = 32
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delay2:
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ldi r19, 64 ; set register, r19 = 64
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delay1:
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ldi r18, 128 ; set register, r18 = 128
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delay0:
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dec r18 ; decrement register, r18 = r18 - 1
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brne delay0 ; if r18 != 0, jump to label delay0
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dec r19 ; decrement register, r19 = r19 -1
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brne delay1 ; if r19 != 0, jump to label delay1
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dec r20 ; decrement register, r20 = r20 -1
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brne delay2 ; if r20 != 0, jump to label delay2
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rjmp loop ; if r20 == 0, jump to label loop
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