timer.c

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#include <avr/io.h>
 
#include "timer.h"
 
// PWM, OC1A 50% dutycycle
int tim1_PWM_init(void) {
  // Set OC1A on PD5 as output
  DDRD |= (1 << PD5);
 
  // Fast PWM,
  // Set Compare Output Mode
  TCCR1A = (1 << COM1A1);
  // Set Clock to PWM fast mode, and prescaler 10(CS10)
  TCCR1B = (1 << WGM13) | (1 << WGM12) | (1 << CS10);
  TCCR1A |= (1 << WGM11);
 
  ICR1L = 0x04; // frequency = fclk/(N*(1+ICR1)) 4 ~983khz
  ICR1H = ((0x04) >> 8);
  OCR1AL = 0x04 / 2; // 50% duty cycle
  OCR1AH = (0x04 / 2 >> 8);
 
  return 0;
}
 
// CTC timer, OC1A
int tim1_CTC_init(void) {
  // Set OC1A on PD5 as output
  DDRD |= (1 << PD5);
 
  // CTC mode, toggle OC1A on compare
  TCCR1A = (1 << COM1A0);
  TCCR1B = (1 << WGM12) | (1 << CS10);
 
  OCR1AL = 0x01; // Compare value
  OCR1AH = 0x01 >> 8;
  // With 4915200 Hz clk, N=8, value =  4915200/(2*8*(1+f_desierd)) = 1 MHz
  // 1 = ~1.23Mhz
 
  return 0;
}