70 lines
1.6 KiB
C
70 lines
1.6 KiB
C
#include <avr/io.h>
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#include "mystd.h"
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#include "utils.h"
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#define D1 PORTB0
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#define D2 PORTB1
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#define D3 PORTB2
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#define D4 PORTB4
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#define PRESCALER 256
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#define TIMER_FREQ (F_CPU / PRESCALER)
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// the PWM is something that counts from 0 to TOP
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// when it reached the value i'll name TOGGLE, it'll set the OUTPUT high
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// when it reaches TOP it'll reset COUNTER and set OUTPUT to low
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//
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// this means we have a clock that reaches TOP every X
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// and during this, we can set TOGGLE such that we set OUTPUT high
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void timer1_init(uint8_t duty) {
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// Set PB1 (OC1A) as output
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DDRB |= _BV(PB1);
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// Non-inverting OC1B -> the OC1B is set to low on TOP reached
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TCCR1A |= _BV(COM1A1);
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// set to PWM-fast with ICR1 as TOP
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TCCR1A |= _BV(WGM11);
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TCCR1B |= _BV(WGM13) | _BV(WGM12);
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// TOP => 1hz
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ICR1 = TIMER_FREQ - 1;
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// TOGGLE => 1/10th of ICR1
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OCR1A = ((TIMER_FREQ / 10) * duty);
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// Start timer with prescaler 256 (CS12)
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TCCR1B |= _BV(CS12);
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}
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#define SW1 PD2
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#define SW2 PD4
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int main(void) {
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uint8_t prev = 0;
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uint8_t duty_cycle = 1;
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timer1_init(duty_cycle);
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while (1) {
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bool has_changed = false;
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// lets read both button in a single byte, and keep track of that too
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uint8_t cur = (PIND & (_BV(SW1) | _BV(SW2)));
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// check for button SW1
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if (prev & (_BV(SW1)) && !(cur & (_BV(SW1)))) {
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duty_cycle++;
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has_changed = true;
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}
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// check for button SW2
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if (prev & (_BV(SW2)) && !(cur & (_BV(SW2)))) {
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duty_cycle--;
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has_changed = true;
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}
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prev = cur;
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if (has_changed) {
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if (duty_cycle > 10)
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duty_cycle = 10;
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if (duty_cycle < 1)
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duty_cycle = 1;
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timer1_init(duty_cycle);
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}
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delay_ms(10);
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}
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}
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