Tooltron

#include "led.h"

#include <avr/io.h>

#include <avr/interrupt.h>

#define PRESCALE 64

#define CLOCK_SEL 3

/* F_CPU / PRESCALE = OCR * 1000 + ERROR */

#define OCR (F_CPU / PRESCALE / 1000UL)

#define ERROR (F_CPU / PRESCALE - OCR * 1000UL)

char blink_count;

enum color_t blink_color;

uint16_t blink_period;

uint16_t ms;

uint16_t error;

static void led_color(enum color_t color) {

  switch (color) {

    case OFF:

      led_off();

      break;

    case RED:

      led_red();

      break;

    case YELLOW:

      led_yellow();

      break;

    case GREEN:

      led_green();

      break;

  }

}

static void blink() {

  blink_count--;

  if (blink_count % 2) {

    led_color(blink_color);

  } else {

    led_off();

  }

}

ISR(TIMER0_COMPA_vect) {

  error += ERROR;

  if (error >= 1000) {

    error -= 1000;

    OCR0A = OCR+1;

  } else {

    OCR0A = OCR;

  }

  ms++;

  if (ms == blink_period) {

    blink();

    if (blink_count == 0) {

      TCCR0B = 0;

    }

    ms = 0;

  }

}

void led_blink_start(unsigned int period_ms, char n_times, enum color_t color) {

  ms = 0;

  error = 0;

  blink_count = n_times*2-1;

  blink_period = period_ms/2;

  blink_color = color;

  led_color(color);

  OCR0A = OCR;

  TIMSK = _BV(OCIE0A);

  TCCR0A = _BV(WGM01);

  TCCR0B = CLOCK_SEL;

}

char led_blink_done() {

  return blink_count == 0;

}