mirror of
https://github.com/sergeyyarkov/attiny24a_led-blink-example.git
synced 2026-10-11 10:18:57 +03:00
66 lines
2.0 KiB
NASM
66 lines
2.0 KiB
NASM
;
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; Project name: led-blink-example
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; Description: Blink an led every one second
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; Source code: https://github.com/sergeyyarkov/attiny24a_led-blink-example
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; Device: ATtiny24A
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; Package: 14-pin-PDIP_SOIC
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; Assembler: gavrasm v5.0
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; Clock frequency: 8MHz with CKDIV8
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; Fuses: lfuse: 0x42, hfuse: 0xDF, efuse: 0xFF, lock:0xFF
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;
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; Written by Sergey Yarkov 23.09.2021
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.device ATtiny24A ; Setup device name
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.list ; Enable listing
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.macro init_stack_p ; Setup stack pointer
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ldi @0, low(@1)
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out SPL, @0
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.endm
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.equ LED_DIR = DDRA ; LED Direction
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.equ LED_PORT = PORTA ; LED Port
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.equ LED_PIN = PINA0 ; LED Pin
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.org 0x00 ; Start program at 0x00
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.cseg ; Code segment
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main: ; Start up program
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init_stack_p r16, RAMEND
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rcall init_ports ; Initialize MCU ports
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loop: ; Program loop
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rcall toggle_led ; Toggle an LED
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rcall delay_1s ; Delay for 1 sec
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rjmp loop ; Jump to program loop again
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toggle_led: ; Toggle an LED
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eor r17, r16 ; Toggle bit
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out LED_PORT, r17 ; Update port of LED
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ret
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init_ports: ; Init MCU ports
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ldi r16, (1<<LED_PIN) ; Load to r16 high bit
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out LED_DIR, r16 ; Set LED direction to output
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ret
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delay_1s: ; For 1MHz frequency
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;
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; Calculate the values of count inner
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; and outer loops to obtain the desired delay.
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.equ outer_count = 100
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.equ inner_count = 2499
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ldi r18, outer_count ; Load outer loop counter value
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_reset: ; Load inner loop counter value
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ldi r24, low(inner_count)
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ldi r25, high(inner_count)
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_loop: ; Delay loop ; e.g inner_count*(2+2)-1 = inner loop cycles
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sbiw r24, 1 ; 2 cycles
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brne _loop ; 2 cycles or 1
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dec r18 ; 1 cycles
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brne _reset ; 2 cycles or 1
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ldi r18, outer_count
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ret |