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/*
FreeRTOS V8.1.1 - Copyright (C) 2014 Real Time Engineers Ltd.
All rights reserved
VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
***************************************************************************
* *
* FreeRTOS provides completely free yet professionally developed, *
* robust, strictly quality controlled, supported, and cross *
* platform software that has become a de facto standard. *
* *
* Help yourself get started quickly and support the FreeRTOS *
* project by purchasing a FreeRTOS tutorial book, reference *
* manual, or both from: http://www.FreeRTOS.org/Documentation *
* *
* Thank you! *
* *
***************************************************************************
This file is part of the FreeRTOS distribution.
FreeRTOS is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License (version 2) as published by the
Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
>>! NOTE: The modification to the GPL is included to allow you to !<<
>>! distribute a combined work that includes FreeRTOS without being !<<
>>! obliged to provide the source code for proprietary components !<<
>>! outside of the FreeRTOS kernel. !<<
FreeRTOS 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. Full license text is available from the following
link: http://www.freertos.org/a00114.html
1 tab == 4 spaces!
***************************************************************************
* *
* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
* *
* http://www.FreeRTOS.org/FAQHelp.html *
* *
***************************************************************************
http://www.FreeRTOS.org - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details.
http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, a DOS
compatible FAT file system, and our tiny thread aware UDP/IP stack.
http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
licenses offer ticketed support, indemnification and middleware.
http://www.SafeRTOS.com - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
1 tab == 4 spaces!
*/
/* 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 long ) 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 long 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 long ulDifference;
volatile unsigned long ulCurrentCount;
static unsigned long 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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