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/*

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

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Copyright (C): Edouard TISSERANT and Francis DUPIN

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AVR Port: Andreas GLAUSER and Peter CHRISTEN

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See COPYING file for copyrights details.

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

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modify it under the terms of the GNU Lesser General Public

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License as published by the Free Software Foundation; either

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

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

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but WITHOUT ANY WARRANTY; without even the implied warranty of

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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

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Lesser General Public License for more details.

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

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

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

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*/

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

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// Includes for the Canfestival driver

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#include "canfestival.h"

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#include "timers.h"

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// Define the timer registers

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#define TimerAlarm        OCR3B

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#define TimerCounter      TCNT3

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

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

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static TIMEVAL last_time_set = TIMEVAL_MAX;     

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void initTimer(void)

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

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

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INPUT	void

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OUTPUT	void

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

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{

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

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

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

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

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}

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void setTimer(TIMEVAL value)

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

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Set the timer for the next alarm.

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INPUT	value TIMEVAL (unsigned long)

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OUTPUT	void

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

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{

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

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}

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TIMEVAL getElapsedTime(void)

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

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

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INPUT	void

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OUTPUT	value TIMEVAL (unsigned long) the elapsed time

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

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{

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

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

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

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  else if (timer < last_time_set)

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

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  else

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    return TIMEVAL_MAX;

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}

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#ifdef  __IAR_SYSTEMS_ICC__

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#pragma type_attribute = __interrupt

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#pragma vector=TIMER3_COMPB_vect

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void TIMER3_COMPB_interrupt(void)

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#else	// GCC

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ISR(TIMER3_COMPB_vect)

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#endif	// GCC

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

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Interruptserviceroutine Timer 3 Compare B for the CAN timer

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

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{

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  last_time_set = TimerCounter;

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

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}

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