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/*
FreeRTOS V7.1.1 - Copyright (C) 2012 Real Time Engineers Ltd.
***************************************************************************
* *
* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
* *
* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
* *
* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
* *
* Thank you for using FreeRTOS, and thank you for your support! *
* *
***************************************************************************
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. See the GNU General Public License for
more details. You should have received a copy of the GNU General Public
License and the FreeRTOS license exception along with FreeRTOS; if not it
can be viewed here: http://www.freertos.org/a00114.html and also obtained
by writing to Richard Barry, contact details for whom are available on the
FreeRTOS WEB site.
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, training, latest information,
license and contact details.
http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool.
Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell
the code with commercial support, indemnification, and middleware, under
the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also
provide a safety engineered and independently SIL3 certified version under
the SafeRTOS brand: http://www.SafeRTOS.com.
*/
/* High speed timer test as described in main.c. */
/* Scheduler includes. */
#include "FreeRTOS.h"
/* Library includes. */
#include "stm32f10x_lib.h"
#include "stm32f10x_tim.h"
#include "stm32f10x_map.h"
/* The set frequency of the interrupt. Deviations from this are measured as
the jitter. */
#define timerINTERRUPT_FREQUENCY ( ( unsigned portSHORT ) 20000 )
/* 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 ( * ( ( unsigned long * ) ( TIMER1_BASE + 0x48 ) ) )
/* The number of interrupts to pass before we start looking at the jitter. */
#define timerSETTLE_TIME 5
/*-----------------------------------------------------------*/
/*
* Configures the two timers used to perform the test.
*/
void vSetupTimerTest( void );
/* Interrupt handler in which the jitter is measured. */
void vTimer2IntHandler( void );
/* Stores the value of the maximum recorded jitter between interrupts. */
volatile unsigned portSHORT usMaxJitter = 0;
/*-----------------------------------------------------------*/
void vSetupTimerTest( void )
{
unsigned long ulFrequency;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
/* Enable timer clocks */
RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM2, ENABLE );
RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM3, ENABLE );
/* Initialise data. */
TIM_DeInit( TIM2 );
TIM_DeInit( TIM3 );
TIM_TimeBaseStructInit( &TIM_TimeBaseStructure );
/* Time base configuration for timer 2 - which generates the interrupts. */
ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
TIM_TimeBaseStructure.TIM_Period = ( unsigned portSHORT ) ( ulFrequency & 0xffffUL );
TIM_TimeBaseStructure.TIM_Prescaler = 0x0;
TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit( TIM2, &TIM_TimeBaseStructure );
TIM_ARRPreloadConfig( TIM2, ENABLE );
/* Configuration for timer 3 which is used as a high resolution time
measurement. */
TIM_TimeBaseStructure.TIM_Period = ( unsigned portSHORT ) 0xffff;
TIM_TimeBaseInit( TIM3, &TIM_TimeBaseStructure );
TIM_ARRPreloadConfig( TIM3, ENABLE );
/* Enable TIM2 IT. TIM3 does not generate an interrupt. */
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = timerHIGHEST_PRIORITY;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init( &NVIC_InitStructure );
TIM_ITConfig( TIM2, TIM_IT_Update, ENABLE );
/* Finally, enable both timers. */
TIM_Cmd( TIM2, ENABLE );
TIM_Cmd( TIM3, ENABLE );
}
/*-----------------------------------------------------------*/
void vTimer2IntHandler( void )
{
static unsigned portSHORT usLastCount = 0, usSettleCount = 0, usMaxDifference = 0;
unsigned portSHORT usThisCount, usDifference;
/* Capture the free running timer 3 value as we enter the interrupt. */
usThisCount = TIM3->CNT;
if( usSettleCount >= timerSETTLE_TIME )
{
/* What is the difference between the timer value in this interrupt
and the value from the last interrupt. */
usDifference = usThisCount - usLastCount;
/* 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( usDifference > usMaxDifference )
{
usMaxDifference = usDifference;
usMaxJitter = usMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
}
}
else
{
/* Don't bother storing any values for the first couple of
interrupts. */
usSettleCount++;
}
/* Remember what the timer value was this time through, so we can calculate
the difference the next time through. */
usLastCount = usThisCount;
TIM_ClearITPendingBit( TIM2, TIM_IT_Update );
}
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