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/*
FreeRTOS.org V4.8.0 - Copyright (C) 2003-2008 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org 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.
FreeRTOS.org 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 FreeRTOS.org; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
***************************************************************************
* *
* SAVE TIME AND MONEY! We can port FreeRTOS.org to your own hardware, *
* and even write all or part of your application on your behalf. *
* See http://www.OpenRTOS.com for details of the services we provide to *
* expedite your project. *
* *
***************************************************************************
***************************************************************************
Please ensure to read the configuration and relevant port sections of the
online documentation.
http://www.FreeRTOS.org - Documentation, latest information, license and
contact details.
http://www.SafeRTOS.com - A version that is certified for use in safety
critical systems.
http://www.OpenRTOS.com - Commercial support, development, porting,
licensing and training services.
*/
/* High speed timer test as described in main.c. */
/* Scheduler includes. */
#include "FreeRTOS.h"
/* Demo includes. */
#include "partest.h"
/* The number of interrupts to pass before we start looking at the jitter. */
#define timerSETTLE_TIME 200
/* The maximum value the 16bit timer can contain. */
#define timerMAX_COUNT 0xffff
/*-----------------------------------------------------------*/
/* The maximum time (in processor clocks) between two consecutive timer
interrupts so far. */
unsigned portLONG ulMaxJitter = 0;
/*-----------------------------------------------------------*/
void vSetupTimerTest( unsigned portSHORT usFrequencyHz )
{
/* T2 is used to generate interrupts. The core timer is used to provide an
accurate time measurement. */
T2CON = 0;
TMR2 = 0;
/* Timer 2 is going to interrupt at usFrequencyHz Hz. */
PR2 = ( unsigned portSHORT ) ( configPERIPHERAL_CLOCK_HZ / ( unsigned portLONG ) usFrequencyHz );
/* Setup timer 2 interrupt priority to be above the kernel priority so
the timer jitter is not effected by the kernel activity. */
ConfigIntTimer2( T2_INT_ON | ( configKERNEL_INTERRUPT_PRIORITY + 1 ) );
/* Clear the interrupt as a starting condition. */
IFS0bits.T2IF = 0;
/* Enable the interrupt. */
IEC0bits.T2IE = 1;
/* Start the timer. */
T2CONbits.TON = 1;
}
/*-----------------------------------------------------------*/
void __attribute__( (interrupt(ipl0), vector(_TIMER_2_VECTOR))) vT2InterruptHandler( void );
void vT2InterruptHandler( void )
{
static unsigned portLONG ulLastCount = 0, ulSettleCount = 0;
static unsigned portLONG ulThisCount, ulDifference;
/* Capture the timer value as we enter the interrupt. */
ulThisCount = _CP0_GET_COUNT();
if( ulSettleCount >= timerSETTLE_TIME )
{
/* What is the difference between the timer value in this interrupt
and the value from the last interrupt. */
ulDifference = ulThisCount - ulLastCount;
/* Store the difference in the timer values if it is larger than the
currently stored largest value. The difference over and above the
expected difference will give the 'jitter' in the processing of these
interrupts. */
if( ulDifference > ulMaxJitter )
{
ulMaxJitter = ulDifference;
}
}
else
{
/* Don't bother storing any values for the first couple of
interrupts. */
ulSettleCount++;
}
/* Remember what the timer value was this time through, so we can calculate
the difference the next time through. */
ulLastCount = ulThisCount;
/* Clear the timer interrupt. */
IFS0bits.T2IF = 0;
}
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