/* * Name: timer.c * Project: AVR-Doper * Author: Christian Starkjohann <cs@obdev.at> * Creation Date: 2006-06-26 * Tabsize: 4 * Copyright: (c) 2006 by Christian Starkjohann, all rights reserved. * License: GNU GPL v2 (see License.txt) or proprietary (CommercialLicense.txt) * Revision: $Id: timer.c 566 2008-04-26 14:21:47Z cs $ */#include "hardware.h"#include <avr/io.h>#include <avr/interrupt.h>#include <avr/wdt.h>#include <util/delay.h>#include "timer.h"volatile uchar  timerTimeoutCnt;volatile uchar  timerLongTimeoutCnt;/* ------------------------------------------------------------------------- */void timerMsDelay(uchar ms){    timerSetupTimeout(ms);    while(!timerTimeoutOccurred());}/* ------------------------------------------------------------------------- */void timerTicksDelay(uchar ticks){char    d, until;    cli();#ifdef SFIOR    SFIOR = _BV(PSR10);     /* reset prescaler */#else    GTCCR = _BV(PSRSYNC);#endif    until = TCNT0 + ticks;    sei();    do{        d = TCNT0 - until;  /* enforce 8 bit arithmetics */    }while(d < 0);}/* ------------------------------------------------------------------------- *//* main configures Timer 0 with 1/64 prescaler * -> 12MHz/64 = 187.5kHz --> 5.333us * overflow every 256 counts = 732.422Hz --> 1.365ms */UTIL_INTERRUPT(SIG_OVERFLOW0)   /* run with global interrupt enable */{static uchar    prescaler = 1;    cli();    if(timerTimeoutCnt != 0)        timerTimeoutCnt--;    sei();  /* allow interrupts here */    cli();    if(--prescaler == 0){   /* scale down to 10 Hz */        prescaler = (uchar)((double)F_CPU / 64 / 256 / 10 + 0.5);        sei();        if(timerLongTimeoutCnt != 0)            timerLongTimeoutCnt--;    }else{        sei();    }}/* ------------------------------------------------------------------------- */void    timerSetupTimeout(uchar msDuration){/* We can either have 12 Mhz clock or roughly 16 MHz (15/16/16.5). The * following is precise enough. */#if F_CPU < 14000000    msDuration -= msDuration >> 2;  /* approximate milliseconds with our timebase */    /* 1 - 1/4 = 0.75; 1.365 ms * 0.75 = 1.024 ms --> 2.4% deviation */#endif    msDuration++;   /* Our resolution is 1.4 ms. Add one unit to avoid almost zero delays for low values */    timerTimeoutCnt = msDuration;}/* ------------------------------------------------------------------------- */