initial commit

.editorconfig

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+[*.c]
+indent_style = tab

.gitignore

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+a.*

Makefile

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+all: a.bin
+
+a.out: main.c
+	avr-gcc -g -Os -mmcu=attiny84a $< -o $@
+
+a.bin: a.out
+	avr-objcopy -O binary $< $@
+
+deploy: a.bin
+	avrdude -p t84a -c stk500v1 -P/dev/tty.usbmodemflip_Rab3gao3 -U flash:w:$<:r

config.h

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+#define OSCILLATOR_CALIBRATION 0x76
+

main.c

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+#include <stdbool.h>
+#include <stdint.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+#include "config.h"
+
+uint32_t ms_since_boot = 0;
+
+ISR(TIM1_COMPA_vect)
+{
+	ms_since_boot++;
+}
+
+void setupio(void) {
+	// Set port A to inputs
+	DDRA = 0x00;
+	PORTA |= PORTA0 | PORTA1; // pull-up
+
+	// Set port B0 to output
+	DDRB = 0x01;
+}
+
+void setup_clock(void) {
+	OSCCAL = OSCILLATOR_CALIBRATION;
+
+	TCCR1B = 0x09;
+	OCR1A = 1000;
+	TIMSK1 = 0x02;
+}
+
+bool button_pressed(uint8_t pin) {
+	return (PINA & (1 << pin)) == 0;
+}
+
+int main() {
+	setupio();
+	setup_clock();
+	sei();
+
+	while(true) {
+		uint32_t sec = ms_since_boot / 1000;
+		if(sec % 2 == 0) {
+			PORTB = 1;
+		} else {
+			PORTB = 0;
+		}
+	}
+}
+