1

/*

     2

This file is part of CanFestival, a library implementing CanOpen Stack.

     3

     4

Copyright (C): Edouard TISSERANT and Francis DUPIN

     5

AVR Port: Andreas GLAUSER and Peter CHRISTEN

     6

     7

See COPYING file for copyrights details.

     8

     9

This library is free software; you can redistribute it and/or

    10

modify it under the terms of the GNU Lesser General Public

    11

License as published by the Free Software Foundation; either

    12

version 2.1 of the License, or (at your option) any later version.

    13

    14

This library is distributed in the hope that it will be useful,

    15

but WITHOUT ANY WARRANTY; without even the implied warranty of

    16

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    17

Lesser General Public License for more details.

    18

    19

You should have received a copy of the GNU Lesser General Public

    20

License along with this library; if not, write to the Free Software

    21

Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    22

*/

    23

    24

// AVR implementation of the  CANopen timer driver, uses Timer 3 (16 bit)

    25

    26

// Includes for the Canfestival driver

    27

#include "canfestival.h"

    28

#include "timer.h"

    29

    30

// Define the timer registers

    31

#define TimerAlarm        OCR3B

    32

#define TimerCounter      TCNT3

    33

    34

/************************** Modul variables **********************************/

    35

// Store the last timer value to calculate the elapsed time

    36

static TIMEVAL last_time_set = TIMEVAL_MAX;     

    37

    38

void initTimer(void)

    39

/******************************************************************************

    40

Initializes the timer, turn on the interrupt and put the interrupt time to zero

    41

INPUT	void

    42

OUTPUT	void

    43

******************************************************************************/

    44

{

    45

  TimerAlarm = 0;		// Set it back to the zero

    46

	// Set timer 3 for CANopen operation tick 8us max, time is 524ms

    47

  TCCR3B = 1 << CS31 | 1 << CS30;       // Timer 3 normal, mit CK/64

    48

  TIMSK3 = 1 << OCIE3B;                 // Enable the interrupt

    49

}

    50

    51

void setTimer(TIMEVAL value)

    52

/******************************************************************************

    53

Set the timer for the next alarm.

    54

INPUT	value TIMEVAL (unsigned long)

    55

OUTPUT	void

    56

******************************************************************************/

    57

{

    58

  TimerAlarm += (int)value;	// Add the desired time to timer interrupt time

    59

}

    60

    61

TIMEVAL getElapsedTime(void)

    62

/******************************************************************************

    63

Return the elapsed time to tell the Stack how much time is spent since last call.

    64

INPUT	void

    65

OUTPUT	value TIMEVAL (unsigned long) the elapsed time

    66

******************************************************************************/

    67

{

    68

  unsigned int timer = TimerCounter;            // Copy the value of the running timer

    69

  if (timer > last_time_set)                    // In case the timer value is higher than the last time.

    70

    return (timer - last_time_set);             // Calculate the time difference

    71

  else if (timer < last_time_set)

    72

    return (last_time_set - timer);             // Calculate the time difference

    73

  else

    74

    return TIMEVAL_MAX;

    75

}

    76

    77

#ifdef  __IAR_SYSTEMS_ICC__

    78

#pragma type_attribute = __interrupt

    79

#pragma vector=TIMER3_COMPB_vect

    80

void TIMER3_COMPB_interrupt(void)

    81

#else	// GCC

    82

ISR(TIMER3_COMPB_vect)

    83

#endif	// GCC

    84

/******************************************************************************

    85

Interruptserviceroutine Timer 3 Compare B for the CAN timer

    86

******************************************************************************/

    87

{

    88

  last_time_set = TimerCounter;

    89

  TimeDispatch();                               // Call the time handler of the stack to adapt the elapsed time

    90

}

    91

    92

    93