2 FreeRTOS V7.0.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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5 ***************************************************************************
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7 * FreeRTOS tutorial books are available in pdf and paperback. *
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8 * Complete, revised, and edited pdf reference manuals are also *
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11 * Purchasing FreeRTOS documentation will not only help you, by *
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12 * ensuring you get running as quickly as possible and with an *
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13 * in-depth knowledge of how to use FreeRTOS, it will also help *
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14 * the FreeRTOS project to continue with its mission of providing *
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15 * professional grade, cross platform, de facto standard solutions *
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16 * for microcontrollers - completely free of charge! *
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18 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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20 * Thank you for using FreeRTOS, and thank you for your support! *
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22 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 >>>NOTE<<< The modification to the GPL is included to allow you to
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31 distribute a combined work that includes FreeRTOS without being obliged to
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32 provide the source code for proprietary components outside of the FreeRTOS
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33 kernel. FreeRTOS is distributed in the hope that it will be useful, but
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34 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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35 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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39 by writing to Richard Barry, contact details for whom are available on the
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44 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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54 /* High speed timer test as described in main.c. */
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56 /* Scheduler includes. */
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57 #include "FreeRTOS.h"
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59 /* Library includes. */
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60 #include "stm32f10x_lib.h"
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61 #include "stm32f10x_tim.h"
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62 #include "stm32f10x_map.h"
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64 /* The set frequency of the interrupt. Deviations from this are measured as
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66 #define timerINTERRUPT_FREQUENCY ( ( unsigned short ) 20000 )
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68 /* The expected time between each of the timer interrupts - if the jitter was
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70 #define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
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72 /* The highest available interrupt priority. */
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73 #define timerHIGHEST_PRIORITY ( 0 )
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76 #define timerMAX_32BIT_VALUE ( 0xffffffffUL )
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77 #define timerTIMER_1_COUNT_VALUE ( * ( ( unsigned long * ) ( TIMER1_BASE + 0x48 ) ) )
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79 /* The number of interrupts to pass before we start looking at the jitter. */
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80 #define timerSETTLE_TIME 5
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82 /*-----------------------------------------------------------*/
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85 * Configures the two timers used to perform the test.
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87 void vSetupHighFrequencyTimer( void );
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89 /* Stores the value of the maximum recorded jitter between interrupts. */
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90 volatile unsigned short usMaxJitter = 0;
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92 /* Variable that counts at 20KHz to provide the time base for the run time
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94 unsigned long ulRunTimeStatsClock = 0UL;
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96 /*-----------------------------------------------------------*/
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98 void vSetupHighFrequencyTimer( void )
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100 unsigned long ulFrequency;
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101 TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
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102 NVIC_InitTypeDef NVIC_InitStructure;
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105 /* Enable timer clocks */
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106 RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM2, ENABLE );
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107 RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM3, ENABLE );
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109 /* Initialise data. */
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110 TIM_DeInit( TIM2 );
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111 TIM_DeInit( TIM3 );
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112 TIM_TimeBaseStructInit( &TIM_TimeBaseStructure );
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114 /* Time base configuration for timer 2 - which generates the interrupts. */
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115 ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
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116 TIM_TimeBaseStructure.TIM_Period = ( unsigned short ) ( ulFrequency & 0xffffUL );
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117 TIM_TimeBaseStructure.TIM_Prescaler = 0x0;
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118 TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
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119 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
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120 TIM_TimeBaseInit( TIM2, &TIM_TimeBaseStructure );
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121 TIM_ARRPreloadConfig( TIM2, ENABLE );
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124 /* Configuration for timer 3 which is used as a high resolution time
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126 TIM_TimeBaseStructure.TIM_Period = ( unsigned short ) 0xffff;
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127 TIM_TimeBaseInit( TIM3, &TIM_TimeBaseStructure );
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128 TIM_ARRPreloadConfig( TIM3, ENABLE );
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130 /* Enable TIM2 IT. TIM3 does not generate an interrupt. */
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131 NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
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132 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
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133 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = timerHIGHEST_PRIORITY;
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134 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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135 NVIC_Init( &NVIC_InitStructure );
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136 TIM_ITConfig( TIM2, TIM_IT_Update, ENABLE );
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138 /* Finally, enable both timers. */
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139 TIM_Cmd( TIM2, ENABLE );
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140 TIM_Cmd( TIM3, ENABLE );
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142 /*-----------------------------------------------------------*/
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144 void TIM2_IRQHandler( void )
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146 static unsigned short usLastCount = 0, usSettleCount = 0, usMaxDifference = 0;
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147 unsigned short usThisCount, usDifference;
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149 /* Capture the free running timer 3 value as we enter the interrupt. */
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150 usThisCount = TIM3->CNT;
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152 if( usSettleCount >= timerSETTLE_TIME )
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154 /* What is the difference between the timer value in this interrupt
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155 and the value from the last interrupt. */
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156 usDifference = usThisCount - usLastCount;
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158 /* Store the difference in the timer values if it is larger than the
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159 currently stored largest value. The difference over and above the
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160 expected difference will give the 'jitter' in the processing of these
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162 if( usDifference > usMaxDifference )
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164 usMaxDifference = usDifference;
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165 usMaxJitter = usMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
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170 /* Don't bother storing any values for the first couple of
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175 /* Remember what the timer value was this time through, so we can calculate
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176 the difference the next time through. */
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177 usLastCount = usThisCount;
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179 /* Keep a count of the number of interrupts as a time base for the run time
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180 stats collection. */
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181 ulRunTimeStatsClock++;
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183 TIM_ClearITPendingBit( TIM2, TIM_IT_Update );
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