43 lines
920 B
C
43 lines
920 B
C
#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "timer_counter.h"
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volatile uint16_t counter = 0;
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void timer0_init(void)
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{
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// Mode CTC: WGM01 = 1, WGM00 = 0
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TCCR0A = (1 << WGM01);
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// Prescaler 64: CS01 = 1, CS00 = 1 (CS02 = 0)
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// TCCR0B = (1 << CS01) | (1 << CS00);
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// Prescaler 8: CS01 = 1, (CS00 = 0, CS02 = 0)
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TCCR0B = (1 << CS01);
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// Setting OCR0A to 124 gives 1 ms with 8 MHz and prescaler of 64
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// OCR0A = 124;
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// Setting OCR0A to 99 gives 100 us with 8 MHz and prescaler of 8
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OCR0A = 99;
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// Enable Timer/Counter0 Output Compare Match A interrupt
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TIMSK0 = (1 << OCIE0A);
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}
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ISR(TIM0_COMPA_vect)
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{
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counter++;
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}
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uint16_t ticks100us(void)
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{
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uint16_t value1, value2;
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// Double-checked locking to ensure atomic read of counter
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do
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{
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value1 = counter;
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value2 = counter;
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} while (value1 != value2);
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return value1;
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} |