132 lines
4.3 KiB
C
132 lines
4.3 KiB
C
/*
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FreeRTOS.org V4.7.2 - Copyright (C) 2003-2008 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FreeRTOS.org 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FreeRTOS.org; 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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A special exception to the GPL can be applied should you wish to distribute
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a combined work that includes FreeRTOS.org, without being obliged to provide
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the source code for any proprietary components. See the licensing section
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of http://www.FreeRTOS.org for full details of how and when the exception
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can be applied.
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***************************************************************************
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Please ensure to read the configuration and relevant port sections of the
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online documentation.
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+++ http://www.FreeRTOS.org +++
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Documentation, latest information, license and contact details.
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+++ http://www.SafeRTOS.com +++
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A version that is certified for use in safety critical systems.
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+++ http://www.OpenRTOS.com +++
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Commercial support, development, porting, licensing and training services.
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***************************************************************************
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*/
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/* High speed timer test as described in main.c. */
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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/* Demo includes. */
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#include "partest.h"
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/* The number of interrupts to pass before we start looking at the jitter. */
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#define timerSETTLE_TIME 200
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/* The maximum value the 16bit timer can contain. */
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#define timerMAX_COUNT 0xffff
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/*-----------------------------------------------------------*/
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/* The maximum time (in processor clocks) between two consecutive timer
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interrupts so far. */
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unsigned portLONG ulMaxJitter = 0;
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/*-----------------------------------------------------------*/
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void vSetupTimerTest( unsigned portSHORT usFrequencyHz )
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{
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/* T2 is used to generate interrupts. The core timer is used to provide an
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accurate time measurement. */
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T2CON = 0;
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TMR2 = 0;
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/* Timer 2 is going to interrupt at usFrequencyHz Hz. */
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PR2 = ( unsigned portSHORT ) ( configPERIPHERAL_CLOCK_HZ / ( unsigned portLONG ) usFrequencyHz );
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/* Setup timer 2 interrupt priority to be above the kernel priority so
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the timer jitter is not effected by the kernel activity. */
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ConfigIntTimer2( T2_INT_ON | ( configKERNEL_INTERRUPT_PRIORITY + 1 ) );
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/* Clear the interrupt as a starting condition. */
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IFS0bits.T2IF = 0;
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/* Enable the interrupt. */
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IEC0bits.T2IE = 1;
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/* Start the timer. */
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T2CONbits.TON = 1;
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}
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/*-----------------------------------------------------------*/
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void __attribute__( (interrupt(ipl0), vector(_TIMER_2_VECTOR))) vT2InterruptHandler( void );
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void vT2InterruptHandler( void )
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{
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static unsigned portLONG ulLastCount = 0, ulSettleCount = 0;
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static unsigned portLONG ulThisCount, ulDifference;
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/* Capture the timer value as we enter the interrupt. */
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ulThisCount = _CP0_GET_COUNT();
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if( ulSettleCount >= timerSETTLE_TIME )
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{
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/* What is the difference between the timer value in this interrupt
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and the value from the last interrupt. */
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ulDifference = ulThisCount - ulLastCount;
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/* Store the difference in the timer values if it is larger than the
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currently stored largest value. The difference over and above the
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expected difference will give the 'jitter' in the processing of these
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interrupts. */
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if( ulDifference > ulMaxJitter )
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{
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ulMaxJitter = ulDifference;
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}
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}
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else
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{
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/* Don't bother storing any values for the first couple of
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interrupts. */
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ulSettleCount++;
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}
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/* Remember what the timer value was this time through, so we can calculate
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the difference the next time through. */
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ulLastCount = ulThisCount;
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/* Clear the timer interrupt. */
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IFS0bits.T2IF = 0;
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}
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