43 lines
617 B
C
43 lines
617 B
C
#include <avr/io.h>
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#include <avr/interrupt.h>
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/* This only works out for a 16MHz or 8MHz clock */
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#define CLOCK_HZ 16000000
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#define TICKS_PER_SECOND (CLOCK_HZ / 256)
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#define TICKS_PER_JIFFY (TICKS_PER_SECOND / 10)
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volatile uint32_t jiffies = 0;
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ISR(TIM1_COMPA_vect)
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{
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jiffies += 1;
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}
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int
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main(void)
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{
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unsigned char counter;
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/*
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* set PORTB for output
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*/
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DDRB = 0xFF;
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PORTB = 0x00;
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TCCR1A = 0;
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TCCR1B = 0;
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TCNT1 = 0;
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OCR1A = TICKS_PER_JIFFY - 1;
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TCCR1B |= (1 << WGM12);
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TCCR1B |= (1 << CS12);
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TIMSK1 |= (1 << OCIE1A);
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sei();
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while (1) {
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PORTB = 0xFF * ((jiffies/ 10) % 2);
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}
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return 0;
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}
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