aversive_10-03-12/modules/base/time_ext/time_ext.c

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/*  
 *  Copyright Droids Corporation (2008)
 * 
 *  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 2 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

/*
 * Author : Julien LE GUEN - jlg@jleguen.info
 */

#include <aversive.h>
#include <aversive/error.h>
#include <aversive/wait.h>

#include <time_ext.h>
#include <time_ext_config.h>

/* Global time variable */
static volatile time_ext_t g_time;


/* Global counters */
static volatile uint32_t g_timer1_cnt;
static volatile uint16_t g_timer1_val;
static volatile uint32_t g_inst_number;
static volatile uint32_t g_frequency;
static volatile uint16_t g_nano_per_inst;

#if 0
/* Function pointer (points to the current interrupt) */
static volatile void (*g_timer1_ovf_interrupt)(void);
static volatile void (*g_timer2_ovf_interrupt)(void);


/*
 *      Interrupt vector: Timer1 OVerFlow
 */
void SIG_OVERFLOW1(void) __attribute__ ((signal));
void SIG_OVERFLOW1(void)
{
        g_timer1_cnt++;
}
#endif


/*
 *      Interrupt vector: Timer2 OVerFlow
 */
void SIG_OVERFLOW2(void) __attribute__ ((signal));
void SIG_OVERFLOW2(void)
{
#if 0
        TCNT1 = 0;
        g_timer1_cnt = 0;
#endif
        /* 256 times NANO_PER_QUARTZ_TICK / prescaler since last overflow */
        g_time.nano += (NANO_PER_QUARTZ_TICK << 8) / time_ext_get_prescaler();

        if(g_time.nano >= NANO_PER_S)
        {
                g_time.nano -= NANO_PER_S;
                g_time.sec++;
        }
}


#if 0
/*
 *      Timer1 overflow interrupt
 *      Basic one, used in production
 */
void timer1_ovf_basic(void)
{
        g_timer1_cnt++;
}

/*
 *      Timer1 overflow interrupt
 *      Calibration
 */
void timer1_ovf_calib(void)
{
        /* Remember how many times we were here */
        g_timer1_cnt++;
}

/*
 *      Timer2 overflow interrupt
 *      Basic one, used in production
 */
void timer2_ovf_basic(void)
{
        TCNT1 = 0;
        g_timer1_cnt = 0;
        /* 256 times NANO_PER_QUARTZ_TICK / prescaler since last overflow */
        g_time.nano += (NANO_PER_QUARTZ_TICK << 8) / time_ext_get_prescaler();

        if(g_time.nano >= NANO_PER_S)
        {
                g_time.nano -= NANO_PER_S;
                g_time.sec++;
        }
}

/*
 *      Timer2 overflow interrupt
 *      Used for crystal calibration
 */ 
void timer2_ovf_calib(void)
{
        /* XXX nothing for now */

        /*      
         *      When calibrating the main crystal, this
         *      interrupt is triggered exactly one second
         *      after the start of the calibration.
         *      This then reads the number of instructions
         *      executed during this second, and deduces the
         *      main crystal frequency.
         *      It then configures the module back to its normal
         *      function (that is, couting time).
         */
        
        /* STOP timers */
        TCCR1B = 0x00;
        TIFR1 = 0xFF;
        TCCR2B = 0x00;
        TIFR2 = 0xFF;

        /* Fetch the value of TCNT1 */
        g_timer1_val = TCNT1; //(((uint16_t)TCNT1H) << 8) + TCNT1L;

        /* Total number of instructions */
        g_inst_number = (((uint32_t)g_timer1_cnt) << 16) + g_timer1_val;

        /* Print that */
        NOTICE(E_TIME_EXT, "%ld instructions in 8 second !", g_inst_number);
        NOTICE(E_TIME_EXT, "timer_val = %d, timer_cnt = %ld", g_timer1_val, g_timer1_cnt);
        g_frequency = g_inst_number >> 3;
        NOTICE(E_TIME_EXT, "Main crystal frequency = %ld Hz", g_frequency);
        g_nano_per_inst = (1000000000UL / g_frequency);
        NOTICE(E_TIME_EXT, "Instruction every %d nanosecond", g_nano_per_inst);

        /* Come back to normal state */
        g_timer1_ovf_interrupt = timer1_ovf_basic;
        g_timer2_ovf_interrupt = timer2_ovf_basic;

        g_timer1_cnt = 0;
        TCNT2 = 0;

        TCCR1B = 0x01;
        TCCR2B = 0x01;
}
#endif




/*
 *      Initialize TIMER2
 */
void time_ext_init(void)
{
        /* 
         * Asynchronous operation of Timer2
         * Some considerations must be taken.
         * See DataSheet for additional information.
         */
        
        NOTICE(E_TIME_EXT, "Initialization");   

#if 0
        /* Set interrupt */
        g_timer1_ovf_interrupt = timer1_ovf_basic;
        g_timer2_ovf_interrupt = timer2_ovf_basic;

        /* Deactivate TIMER1 */
        TIMSK1 = 0x00;
        TCCR1A = 0x00;
        TCCR1B = 0x00;
        TCNT1 = 0x00;
        g_timer1_val = 0;
        g_timer1_cnt = 0;
#endif

        /* Asynchronous mode:
         *      EXCLK = 0 (we have an oscillator)
         *      AS2 = 1
         *      other bits are read only
         */
        ASSR = _BV(AS2);
        /* We want a 'normal' operation mode */
        TCCR2A = 0x00;
        /* Clock Select: no prescaling */
        TCCR2B = 0x01;
        /* Reset the counter */
        TCNT2 = 0x00;
        /* We want an interrupt when TCNT2 overflows */
        TIMSK2 = _BV(TOIE2);


        g_time.sec = 0;
        g_time.nano = 0;
}


/*
 *      Change the prescaler
 */
inline void time_ext_set_prescaler(uint8_t p)
{
        /* Prevent fools to pass an incorrect value */
        TCCR2B = p & 0x07;
}

/*
 *      Get the prescaler value
 */
inline uint8_t time_ext_get_prescaler(void)
{
        return TCCR2B & 0x07;
}

#if 0
/*
 *      Calibration of main crystal
 */
void time_ext_calib(void)
{
        /*
         *      Configure TIMER1 and all the stuff
         *      No prescaler, normal mode, interrupt on OVF
         */
        TCCR1A = 0x00;
        TCCR1B = 0x00;
        TIMSK1 = _BV(TOIE1);
        TIFR1 = 0xFF;   /* clear flags */

        /* Configure TIMER2 */
        time_ext_set_prescaler(TIMER2_PRESCALER_OFF);

        /* Change the interrupt handlers */
        g_timer1_ovf_interrupt = timer1_ovf_calib;
        g_timer2_ovf_interrupt = timer2_ovf_calib;

        g_frequency = 0;
        g_nano_per_inst = 0;
        g_inst_number = 0;

        g_timer1_cnt = 0;
        g_timer1_val = 0;
        TCNT1 = 0;
        TCNT2 = 0;
        
        /* Launch the prescalers -> timers ON */
        TCCR2B = TIMER2_PRESCALER_1024;
        TCCR1B = 0x01;
}
#endif


/*
 *      Get time.
 *      Since we only update g_time when TCNT2 overflows,
 *      we add the value of TCNT2 to the nano field.
 */
inline uint32_t time_ext_get_s(void)
{
        return g_time.sec;
}

inline uint32_t time_ext_get_ns(void)
{
        uint32_t tmp, tmp1;
        /* Fetch timer1 value */
        //tmp1 = TCNT1;
        
        tmp = ((uint32_t)TCNT2) * NANO_PER_QUARTZ_TICK / time_ext_get_prescaler();
        //tmp += tmp1 * g_nano_per_inst;

        return g_time.nano + tmp;
}

time_ext_t time_ext_get(void)
{
        time_ext_t t;
        t.nano = time_ext_get_ns();
        t.sec = time_ext_get_s();
        if(t.nano >= NANO_PER_S) {
                t.sec++;
                t.nano -= NANO_PER_S;
        }
        return t;
}


/*
 *      Set the time
 *      Resets TCNT2 as well
 */
inline void time_ext_set(uint32_t sec, uint32_t nano)
{
        TCNT2 = 0;
        g_time.nano = nano;
        g_time.sec = sec;
        NOTICE(E_TIME_EXT, "Time set to %ld %ld", sec, nano);
}

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