40 lines
844 B
C
40 lines
844 B
C
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "mystd.h"
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#include "utils.h"
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#define PRESCALER 1024
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#define TIMER_FREQ (F_CPU / PRESCALER)
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// at a high level:
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// Set the OC1B (PB2) pin as output
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// set the TIMER1 mode to COMPARE (CTC)
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// say to compare against OC1A
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// set the value to be compated at X count
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// say the presacler for the timer is 512
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//
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// all these information are on page ~140
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void timer1_init(void) {
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// Set PB1 (OC1A) as output
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DDRB |= _BV(PB1);
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// CTC mode (WGM12 = 1)
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TCCR1B |= _BV(WGM12);
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// Toggle OC1B on compare match (COM1B0 = 1)
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TCCR1A |= _BV(COM1A0);
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// Set compare values
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OCR1A = TIMER_FREQ * 2;
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// Start timer with prescaler 1024 (CS12 | CS10)
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TCCR1B |= _BV(CS12) | _BV(CS10);
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// set OCR1A interrupt
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TIMSK1 = _BV(1);
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// HELLO NO `sei()` SO WE DO IT BY HAND
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SREG |= (1 << 7);
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}
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