2 FreeRTOS V5.4.0 - Copyright (C) 2003-2009 Richard Barry.
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4 This file is part of the FreeRTOS distribution.
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6 FreeRTOS is free software; you can redistribute it and/or modify it under
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7 the terms of the GNU General Public License (version 2) as published by the
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8 Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS without being obliged to provide the
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11 source code for proprietary components outside of the FreeRTOS kernel.
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12 Alternative commercial license and support terms are also available upon
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13 request. See the licensing section of http://www.FreeRTOS.org for full
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16 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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18 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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21 You should have received a copy of the GNU General Public License along
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22 with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
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23 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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26 ***************************************************************************
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28 * Looking for a quick start? Then check out the FreeRTOS eBook! *
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29 * See http://www.FreeRTOS.org/Documentation for details *
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31 ***************************************************************************
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35 Please ensure to read the configuration and relevant port sections of the
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36 online documentation.
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38 http://www.FreeRTOS.org - Documentation, latest information, license and
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41 http://www.SafeRTOS.com - A version that is certified for use in safety
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44 http://www.OpenRTOS.com - Commercial support, development, porting,
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45 licensing and training services.
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48 /* High speed timer test as described in main.c. */
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50 /* Scheduler includes. */
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51 #include "FreeRTOS.h"
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53 /* Library includes. */
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54 #include "stm32f10x_lib.h"
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55 #include "stm32f10x_tim.h"
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56 #include "stm32f10x_map.h"
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58 /* The set frequency of the interrupt. Deviations from this are measured as
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60 #define timerINTERRUPT_FREQUENCY ( ( unsigned portSHORT ) 20000 )
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62 /* The expected time between each of the timer interrupts - if the jitter was
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64 #define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
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66 /* The highest available interrupt priority. */
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67 #define timerHIGHEST_PRIORITY ( 0 )
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70 #define timerMAX_32BIT_VALUE ( 0xffffffffUL )
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71 #define timerTIMER_1_COUNT_VALUE ( * ( ( unsigned long * ) ( TIMER1_BASE + 0x48 ) ) )
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73 /* The number of interrupts to pass before we start looking at the jitter. */
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74 #define timerSETTLE_TIME 5
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76 /*-----------------------------------------------------------*/
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79 * Configures the two timers used to perform the test.
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81 void vSetupHighFrequencyTimer( void );
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83 /* Stores the value of the maximum recorded jitter between interrupts. */
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84 volatile unsigned portSHORT usMaxJitter = 0;
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86 /* Variable that counts at 20KHz to provide the time base for the run time
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88 unsigned long ulRunTimeStatsClock = 0UL;
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90 /*-----------------------------------------------------------*/
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92 void vSetupHighFrequencyTimer( void )
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94 unsigned long ulFrequency;
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95 TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
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96 NVIC_InitTypeDef NVIC_InitStructure;
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99 /* Enable timer clocks */
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100 RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM2, ENABLE );
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101 RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM3, ENABLE );
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103 /* Initialise data. */
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104 TIM_DeInit( TIM2 );
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105 TIM_DeInit( TIM3 );
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106 TIM_TimeBaseStructInit( &TIM_TimeBaseStructure );
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108 /* Time base configuration for timer 2 - which generates the interrupts. */
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109 ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
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110 TIM_TimeBaseStructure.TIM_Period = ( unsigned portSHORT ) ( ulFrequency & 0xffffUL );
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111 TIM_TimeBaseStructure.TIM_Prescaler = 0x0;
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112 TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
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113 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
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114 TIM_TimeBaseInit( TIM2, &TIM_TimeBaseStructure );
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115 TIM_ARRPreloadConfig( TIM2, ENABLE );
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118 /* Configuration for timer 3 which is used as a high resolution time
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120 TIM_TimeBaseStructure.TIM_Period = ( unsigned portSHORT ) 0xffff;
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121 TIM_TimeBaseInit( TIM3, &TIM_TimeBaseStructure );
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122 TIM_ARRPreloadConfig( TIM3, ENABLE );
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124 /* Enable TIM2 IT. TIM3 does not generate an interrupt. */
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125 NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
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126 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
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127 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = timerHIGHEST_PRIORITY;
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128 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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129 NVIC_Init( &NVIC_InitStructure );
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130 TIM_ITConfig( TIM2, TIM_IT_Update, ENABLE );
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132 /* Finally, enable both timers. */
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133 TIM_Cmd( TIM2, ENABLE );
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134 TIM_Cmd( TIM3, ENABLE );
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136 /*-----------------------------------------------------------*/
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138 void TIM2_IRQHandler( void )
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140 static unsigned portSHORT usLastCount = 0, usSettleCount = 0, usMaxDifference = 0;
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141 unsigned portSHORT usThisCount, usDifference;
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143 /* Capture the free running timer 3 value as we enter the interrupt. */
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144 usThisCount = TIM3->CNT;
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146 if( usSettleCount >= timerSETTLE_TIME )
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148 /* What is the difference between the timer value in this interrupt
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149 and the value from the last interrupt. */
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150 usDifference = usThisCount - usLastCount;
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152 /* Store the difference in the timer values if it is larger than the
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153 currently stored largest value. The difference over and above the
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154 expected difference will give the 'jitter' in the processing of these
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156 if( usDifference > usMaxDifference )
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158 usMaxDifference = usDifference;
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159 usMaxJitter = usMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
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164 /* Don't bother storing any values for the first couple of
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169 /* Remember what the timer value was this time through, so we can calculate
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170 the difference the next time through. */
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171 usLastCount = usThisCount;
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173 /* Keep a count of the number of interrupts as a time base for the run time
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174 stats collection. */
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175 ulRunTimeStatsClock++;
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177 TIM_ClearITPendingBit( TIM2, TIM_IT_Update );
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