text: /*
      FreeRTOS V7.6.0 - Copyright (C) 2013 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 "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 );
  }
  
  
  
  
  
  
  
  
  