32 lines
619 B
C
32 lines
619 B
C
#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "millis.h"
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volatile unsigned long _millis; // for millis tick !! Overflow every ~49.7 days
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// Timer0
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// 1ms IRQ
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// Used for millis() timing
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void timer0_init()
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{
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TCCR0A = (1<<WGM01); //TIMER0 SET-UP: CTC MODE
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TCCR0B = (1<<CS01)|(1<<CS00); // PS 1:64
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OCR0A = 249; // 1ms reach for clear (16mz:64=>250kHz:250-=>1kHz)
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TIMSK0 |= 1<<OCIE0A; //IRQ on TIMER0 output compareA
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}
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ISR (TIMER0_COMPA_vect)
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{
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_millis++; // INC millis tick
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}
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unsigned long millis(void)
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{
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unsigned long i;
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cli();
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// Atomic tick reading
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i = _millis;
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sei();
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return i;
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}
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