timer.c

/* 
 * Open-BLDC Firmware, Firmware for BrushLess Drive Controllers
 * Copyright (C) 2009 Piotr Esden-Tempski <piotr at esden.net>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <avr/interrupt.h>
#include <stdint.h>

#include "timer.h"

uint16_t timer_sw_counter = 0;

//#define TIMER_VAL (((uint16_t)TCNT0)|(((uint16_t)timer_overflow_counter)<<8))
#define TIMER_VAL TCNT0

void timer_init_0();

void timer_init() {
    timer_init_0();
}

void timer_init_0() {
    TIMSK = (1 << TOIE0); // Timer/Counter0 Overflow Interrupt Enable
    TCCR0 = (0 << CS02) | (1 << CS01) | (0 << CS00); // clk/8 => 1 MHz
}

void timer_wait(uint8_t time_in_us) {
    time_in_us = (uint8_t) TCNT0 + time_in_us;
    while ((TCNT0 - time_in_us) & 0x80) {
        asm("nop");
    }
}

/* start new stopwatch */
uint16_t timer_new_sw_ms(uint16_t time_in_ms) {
    return (timer_sw_counter + (time_in_ms * 1000L / 256));
}

uint16_t timer_sw_check(uint16_t sw_in_ms) {
    return ((sw_in_ms - timer_sw_counter) & 0x8000) >> 8;
}

ISR(TIMER0_OVF_vect)
{
    timer_sw_counter++;
}