2 FreeRTOS V7.2.0 - Copyright (C) 2012 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 ***************************************************************************
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46 * Having a problem? Start by reading the FAQ "My application does *
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47 * not run, what could be wrong? *
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49 * http://www.FreeRTOS.org/FAQHelp.html *
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51 ***************************************************************************
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54 http://www.FreeRTOS.org - Documentation, training, latest information,
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55 license and contact details.
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57 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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58 including FreeRTOS+Trace - an indispensable productivity tool.
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60 Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell
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61 the code with commercial support, indemnification, and middleware, under
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62 the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also
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63 provide a safety engineered and independently SIL3 certified version under
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64 the SafeRTOS brand: http://www.SafeRTOS.com.
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67 /* High speed timer test as described in main.c. */
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69 /* Scheduler includes. */
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70 #include "FreeRTOS.h"
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72 /* Library includes. */
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73 #include "stm32f10x_lib.h"
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74 #include "stm32f10x_tim.h"
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75 #include "stm32f10x_map.h"
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77 /* The set frequency of the interrupt. Deviations from this are measured as
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79 #define timerINTERRUPT_FREQUENCY ( ( unsigned short ) 20000 )
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81 /* The expected time between each of the timer interrupts - if the jitter was
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83 #define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
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85 /* The highest available interrupt priority. */
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86 #define timerHIGHEST_PRIORITY ( 0 )
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89 #define timerMAX_32BIT_VALUE ( 0xffffffffUL )
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90 #define timerTIMER_1_COUNT_VALUE ( * ( ( unsigned long * ) ( TIMER1_BASE + 0x48 ) ) )
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92 /* The number of interrupts to pass before we start looking at the jitter. */
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93 #define timerSETTLE_TIME 5
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95 /*-----------------------------------------------------------*/
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98 * Configures the two timers used to perform the test.
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100 void vSetupHighFrequencyTimer( void );
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102 /* Stores the value of the maximum recorded jitter between interrupts. */
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103 volatile unsigned short usMaxJitter = 0;
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105 /* Variable that counts at 20KHz to provide the time base for the run time
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107 unsigned long ulRunTimeStatsClock = 0UL;
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109 /*-----------------------------------------------------------*/
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111 void vSetupHighFrequencyTimer( void )
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113 unsigned long ulFrequency;
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114 TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
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115 NVIC_InitTypeDef NVIC_InitStructure;
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118 /* Enable timer clocks */
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119 RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM2, ENABLE );
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120 RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM3, ENABLE );
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122 /* Initialise data. */
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123 TIM_DeInit( TIM2 );
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124 TIM_DeInit( TIM3 );
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125 TIM_TimeBaseStructInit( &TIM_TimeBaseStructure );
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127 /* Time base configuration for timer 2 - which generates the interrupts. */
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128 ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
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129 TIM_TimeBaseStructure.TIM_Period = ( unsigned short ) ( ulFrequency & 0xffffUL );
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130 TIM_TimeBaseStructure.TIM_Prescaler = 0x0;
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131 TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
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132 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
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133 TIM_TimeBaseInit( TIM2, &TIM_TimeBaseStructure );
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134 TIM_ARRPreloadConfig( TIM2, ENABLE );
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137 /* Configuration for timer 3 which is used as a high resolution time
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139 TIM_TimeBaseStructure.TIM_Period = ( unsigned short ) 0xffff;
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140 TIM_TimeBaseInit( TIM3, &TIM_TimeBaseStructure );
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141 TIM_ARRPreloadConfig( TIM3, ENABLE );
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143 /* Enable TIM2 IT. TIM3 does not generate an interrupt. */
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144 NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
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145 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
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146 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = timerHIGHEST_PRIORITY;
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147 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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148 NVIC_Init( &NVIC_InitStructure );
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149 TIM_ITConfig( TIM2, TIM_IT_Update, ENABLE );
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151 /* Finally, enable both timers. */
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152 TIM_Cmd( TIM2, ENABLE );
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153 TIM_Cmd( TIM3, ENABLE );
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155 /*-----------------------------------------------------------*/
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157 void TIM2_IRQHandler( void )
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159 static unsigned short usLastCount = 0, usSettleCount = 0, usMaxDifference = 0;
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160 unsigned short usThisCount, usDifference;
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162 /* Capture the free running timer 3 value as we enter the interrupt. */
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163 usThisCount = TIM3->CNT;
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165 if( usSettleCount >= timerSETTLE_TIME )
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167 /* What is the difference between the timer value in this interrupt
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168 and the value from the last interrupt. */
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169 usDifference = usThisCount - usLastCount;
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171 /* Store the difference in the timer values if it is larger than the
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172 currently stored largest value. The difference over and above the
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173 expected difference will give the 'jitter' in the processing of these
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175 if( usDifference > usMaxDifference )
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177 usMaxDifference = usDifference;
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178 usMaxJitter = usMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
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183 /* Don't bother storing any values for the first couple of
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188 /* Remember what the timer value was this time through, so we can calculate
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189 the difference the next time through. */
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190 usLastCount = usThisCount;
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192 /* Keep a count of the number of interrupts as a time base for the run time
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193 stats collection. */
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194 ulRunTimeStatsClock++;
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196 TIM_ClearITPendingBit( TIM2, TIM_IT_Update );
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