www.pudn.com > CanFestival-3-1041153c5fd2.zip > timer_AVR.c, change:2011-04-13,size:3561b

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

Copyright (C): Edouard TISSERANT and Francis DUPIN
AVR Port: Andreas GLAUSER and Peter CHRISTEN

See COPYING file for copyrights details.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

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

// Includes for the Canfestival driver
#include "canfestival.h"
#include "timer.h"

// Define the timer registers
#define TimerAlarm        OCR3B
#define TimerCounter      TCNT3

/************************** Modul variables **********************************/
// Store the last timer value to calculate the elapsed time
static TIMEVAL last_time_set = TIMEVAL_MAX;     

void initTimer(void)
Initializes the timer, turn on the interrupt and put the interrupt time to zero
INPUT	void
  TimerAlarm = 0;		// Set it back to the zero
	// Set timer 3 for CANopen operation tick 8us max, time is 524ms
  TCCR3B = 1 << CS31 | 1 << CS30;       // Timer 3 normal, mit CK/64
  TIMSK3 = 1 << OCIE3B;                 // Enable the interrupt

void setTimer(TIMEVAL value)
Set the timer for the next alarm.
INPUT	value TIMEVAL (unsigned long)
  TimerAlarm += (int)value;	// Add the desired time to timer interrupt time

TIMEVAL getElapsedTime(void)
Return the elapsed time to tell the Stack how much time is spent since last call.
INPUT	void
OUTPUT	value TIMEVAL (unsigned long) the elapsed time
  unsigned int timer = TimerCounter;            // Copy the value of the running timer
  if (timer > last_time_set)                    // In case the timer value is higher than the last time.
    return (timer - last_time_set);             // Calculate the time difference
  else if (timer < last_time_set)
    return (last_time_set - timer);             // Calculate the time difference
    return TIMEVAL_MAX;

#ifdef  __IAR_SYSTEMS_ICC__
#pragma type_attribute = __interrupt
#pragma vector=TIMER3_COMPB_vect
void TIMER3_COMPB_interrupt(void)
#else	// GCC
#endif	// GCC
Interruptserviceroutine Timer 3 Compare B for the CAN timer
  last_time_set = TimerCounter;
  TimeDispatch();                               // Call the time handler of the stack to adapt the elapsed time