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/*
FreeRTOS.org V5.1.1 - 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"
/* Library includes. */
#include "hw_ints.h"
#include "hw_memmap.h"
#include "hw_types.h"
#include "interrupt.h"
#include "sysctl.h"
#include "lmi_timer.h"
#include "hw_timer.h"
/* The set frequency of the interrupt. Deviations from this are measured as
the jitter. */
#define timerINTERRUPT_FREQUENCY ( 20000UL )
/* The expected time between each of the timer interrupts - if the jitter was
zero. */
#define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
/* The highest available interrupt priority. */
#define timerHIGHEST_PRIORITY ( 0 )
/* Misc defines. */
#define timerMAX_32BIT_VALUE ( 0xffffffffUL )
#define timerTIMER_1_COUNT_VALUE ( * ( ( volatile unsigned long * ) ( ( unsigned portLONG ) TIMER1_BASE + 0x48UL ) ) )
/*-----------------------------------------------------------*/
/* Interrupt handler in which the jitter is measured. */
void Timer0IntHandler( void );
/* Stores the value of the maximum recorded jitter between interrupts. */
volatile unsigned portLONG ulMaxJitter = 0;
/*-----------------------------------------------------------*/
void vSetupHighFrequencyTimer( void )
{
unsigned long ulFrequency;
/* Timer zero is used to generate the interrupts, and timer 1 is used
to measure the jitter. */
SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER0 );
SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER1 );
TimerConfigure( TIMER0_BASE, TIMER_CFG_32_BIT_PER );
TimerConfigure( TIMER1_BASE, TIMER_CFG_32_BIT_PER );
/* Set the timer interrupt to be above the kernel - highest. */
IntPrioritySet( INT_TIMER0A, timerHIGHEST_PRIORITY );
/* Just used to measure time. */
TimerLoadSet(TIMER1_BASE, TIMER_A, timerMAX_32BIT_VALUE );
/* Ensure interrupts do not start until the scheduler is running. */
portDISABLE_INTERRUPTS();
/* The rate at which the timer will interrupt. */
ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
TimerLoadSet( TIMER0_BASE, TIMER_A, ulFrequency );
IntEnable( INT_TIMER0A );
TimerIntEnable( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
/* Enable both timers. */
TimerEnable( TIMER0_BASE, TIMER_A );
TimerEnable( TIMER1_BASE, TIMER_A );
}
/*-----------------------------------------------------------*/
void Timer0IntHandler( void )
{
unsigned portLONG ulDifference;
volatile unsigned portLONG ulCurrentCount;
static unsigned portLONG ulMaxDifference = 0, ulLastCount = 0;
/* We use the timer 1 counter value to measure the clock cycles between
the timer 0 interrupts. */
ulCurrentCount = timerTIMER_1_COUNT_VALUE;
TimerIntClear( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
if( ulCurrentCount < ulLastCount )
{
/* How many times has timer 1 counted since the last interrupt? */
ulDifference = ulLastCount - ulCurrentCount;
/* Is this the largest difference we have measured yet? */
if( ulDifference > ulMaxDifference )
{
ulMaxDifference = ulDifference;
ulMaxJitter = ulMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
}
}
ulLastCount = ulCurrentCount;
}
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