2 FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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5 http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS tutorial books are available in pdf and paperback. *
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10 * Complete, revised, and edited pdf reference manuals are also *
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13 * Purchasing FreeRTOS documentation will not only help you, by *
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14 * ensuring you get running as quickly as possible and with an *
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15 * in-depth knowledge of how to use FreeRTOS, it will also help *
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16 * the FreeRTOS project to continue with its mission of providing *
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17 * professional grade, cross platform, de facto standard solutions *
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18 * for microcontrollers - completely free of charge! *
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20 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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22 * Thank you for using FreeRTOS, and thank you for your support! *
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24 ***************************************************************************
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27 This file is part of the FreeRTOS distribution.
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29 FreeRTOS is free software; you can redistribute it and/or modify it under
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30 the terms of the GNU General Public License (version 2) as published by the
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31 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not it can be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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75 /* High speed timer test as described in main.c. */
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77 /* Scheduler includes. */
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78 #include "FreeRTOS.h"
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80 /* Library includes. */
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81 #include "stm32f10x_lib.h"
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82 #include "stm32f10x_tim.h"
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83 #include "stm32f10x_map.h"
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85 /* The set frequency of the interrupt. Deviations from this are measured as
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87 #define timerINTERRUPT_FREQUENCY ( ( unsigned short ) 20000 )
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89 /* The expected time between each of the timer interrupts - if the jitter was
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91 #define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
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93 /* The highest available interrupt priority. */
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94 #define timerHIGHEST_PRIORITY ( 0 )
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97 #define timerMAX_32BIT_VALUE ( 0xffffffffUL )
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98 #define timerTIMER_1_COUNT_VALUE ( * ( ( unsigned long * ) ( TIMER1_BASE + 0x48 ) ) )
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100 /* The number of interrupts to pass before we start looking at the jitter. */
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101 #define timerSETTLE_TIME 5
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103 /*-----------------------------------------------------------*/
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106 * Configures the two timers used to perform the test.
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108 void vSetupHighFrequencyTimer( void );
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110 /* Stores the value of the maximum recorded jitter between interrupts. */
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111 volatile unsigned short usMaxJitter = 0;
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113 /* Variable that counts at 20KHz to provide the time base for the run time
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115 unsigned long ulRunTimeStatsClock = 0UL;
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117 /*-----------------------------------------------------------*/
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119 void vSetupHighFrequencyTimer( void )
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121 unsigned long ulFrequency;
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122 TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
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123 NVIC_InitTypeDef NVIC_InitStructure;
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126 /* Enable timer clocks */
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127 RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM2, ENABLE );
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128 RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM3, ENABLE );
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130 /* Initialise data. */
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131 TIM_DeInit( TIM2 );
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132 TIM_DeInit( TIM3 );
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133 TIM_TimeBaseStructInit( &TIM_TimeBaseStructure );
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135 /* Time base configuration for timer 2 - which generates the interrupts. */
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136 ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
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137 TIM_TimeBaseStructure.TIM_Period = ( unsigned short ) ( ulFrequency & 0xffffUL );
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138 TIM_TimeBaseStructure.TIM_Prescaler = 0x0;
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139 TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
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140 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
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141 TIM_TimeBaseInit( TIM2, &TIM_TimeBaseStructure );
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142 TIM_ARRPreloadConfig( TIM2, ENABLE );
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145 /* Configuration for timer 3 which is used as a high resolution time
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147 TIM_TimeBaseStructure.TIM_Period = ( unsigned short ) 0xffff;
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148 TIM_TimeBaseInit( TIM3, &TIM_TimeBaseStructure );
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149 TIM_ARRPreloadConfig( TIM3, ENABLE );
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151 /* Enable TIM2 IT. TIM3 does not generate an interrupt. */
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152 NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
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153 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
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154 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = timerHIGHEST_PRIORITY;
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155 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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156 NVIC_Init( &NVIC_InitStructure );
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157 TIM_ITConfig( TIM2, TIM_IT_Update, ENABLE );
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159 /* Finally, enable both timers. */
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160 TIM_Cmd( TIM2, ENABLE );
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161 TIM_Cmd( TIM3, ENABLE );
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163 /*-----------------------------------------------------------*/
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165 void TIM2_IRQHandler( void )
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167 static unsigned short usLastCount = 0, usSettleCount = 0, usMaxDifference = 0;
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168 unsigned short usThisCount, usDifference;
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170 /* Capture the free running timer 3 value as we enter the interrupt. */
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171 usThisCount = TIM3->CNT;
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173 if( usSettleCount >= timerSETTLE_TIME )
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175 /* What is the difference between the timer value in this interrupt
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176 and the value from the last interrupt. */
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177 usDifference = usThisCount - usLastCount;
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179 /* Store the difference in the timer values if it is larger than the
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180 currently stored largest value. The difference over and above the
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181 expected difference will give the 'jitter' in the processing of these
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183 if( usDifference > usMaxDifference )
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185 usMaxDifference = usDifference;
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186 usMaxJitter = usMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
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191 /* Don't bother storing any values for the first couple of
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196 /* Remember what the timer value was this time through, so we can calculate
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197 the difference the next time through. */
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198 usLastCount = usThisCount;
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200 /* Keep a count of the number of interrupts as a time base for the run time
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201 stats collection. */
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202 ulRunTimeStatsClock++;
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204 TIM_ClearITPendingBit( TIM2, TIM_IT_Update );
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