2 FreeRTOS V7.3.0 - Copyright (C) 2012 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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32 >>>NOTE<<< The modification to the GPL is included to allow you to
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33 distribute a combined work that includes FreeRTOS without being obliged to
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34 provide the source code for proprietary components outside of the FreeRTOS
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35 kernel. FreeRTOS is distributed in the hope that it will be useful, but
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36 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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37 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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38 more details. You should have received a copy of the GNU General Public
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39 License and the FreeRTOS license exception along with FreeRTOS; if not it
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40 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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41 by writing to Richard Barry, contact details for whom are available on the
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46 ***************************************************************************
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48 * Having a problem? Start by reading the FAQ "My application does *
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49 * not run, what could be wrong?" *
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51 * http://www.FreeRTOS.org/FAQHelp.html *
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53 ***************************************************************************
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56 http://www.FreeRTOS.org - Documentation, training, latest versions, license
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57 and contact details.
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59 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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60 including FreeRTOS+Trace - an indispensable productivity tool.
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62 Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell
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63 the code with commercial support, indemnification, and middleware, under
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64 the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also
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65 provide a safety engineered and independently SIL3 certified version under
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66 the SafeRTOS brand: http://www.SafeRTOS.com.
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69 /* High speed timer test as described in main.c. */
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71 /* Scheduler includes. */
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72 #include "FreeRTOS.h"
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74 /* Library includes. */
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75 #include "hw_ints.h"
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76 #include "hw_memmap.h"
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77 #include "hw_types.h"
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78 #include "interrupt.h"
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80 #include "lmi_timer.h"
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82 /* The set frequency of the interrupt. Deviations from this are measured as
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84 #define timerINTERRUPT_FREQUENCY ( 20000UL )
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86 /* The expected time between each of the timer interrupts - if the jitter was
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88 #define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
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90 /* The highest available interrupt priority. */
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91 #define timerHIGHEST_PRIORITY ( 0 )
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94 #define timerMAX_32BIT_VALUE ( 0xffffffffUL )
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95 #define timerTIMER_1_COUNT_VALUE ( * ( ( unsigned long * ) ( TIMER1_BASE + 0x48 ) ) )
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97 /*-----------------------------------------------------------*/
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99 /* Interrupt handler in which the jitter is measured. */
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100 void Timer0IntHandler( void );
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102 /* Stores the value of the maximum recorded jitter between interrupts. */
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103 volatile unsigned portLONG ulMaxJitter = 0UL;
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105 /* Counts the total number of times that the high frequency timer has 'ticked'.
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106 This value is used by the run time stats function to work out what percentage
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107 of CPU time each task is taking. */
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108 volatile unsigned portLONG ulHighFrequencyTimerTicks = 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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115 /* Timer zero is used to generate the interrupts, and timer 1 is used
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116 to measure the jitter. */
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117 SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER0 );
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118 SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER1 );
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119 TimerConfigure( TIMER0_BASE, TIMER_CFG_32_BIT_PER );
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120 TimerConfigure( TIMER1_BASE, TIMER_CFG_32_BIT_PER );
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122 /* Set the timer interrupt to be above the kernel - highest. */
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123 IntPrioritySet( INT_TIMER0A, timerHIGHEST_PRIORITY );
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125 /* Just used to measure time. */
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126 TimerLoadSet(TIMER1_BASE, TIMER_A, timerMAX_32BIT_VALUE );
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128 /* Ensure interrupts do not start until the scheduler is running. */
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129 portDISABLE_INTERRUPTS();
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131 /* The rate at which the timer will interrupt. */
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132 ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
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133 TimerLoadSet( TIMER0_BASE, TIMER_A, ulFrequency );
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134 IntEnable( INT_TIMER0A );
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135 TimerIntEnable( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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137 /* Enable both timers. */
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138 TimerEnable( TIMER0_BASE, TIMER_A );
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139 TimerEnable( TIMER1_BASE, TIMER_A );
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141 /*-----------------------------------------------------------*/
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143 void Timer0IntHandler( void )
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145 unsigned portLONG ulDifference;
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146 volatile unsigned portLONG ulCurrentCount;
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147 static unsigned portLONG ulMaxDifference = 0, ulLastCount = 0;
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149 /* We use the timer 1 counter value to measure the clock cycles between
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150 the timer 0 interrupts. */
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151 ulCurrentCount = timerTIMER_1_COUNT_VALUE;
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153 TimerIntClear( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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155 if( ulCurrentCount < ulLastCount )
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157 /* How many times has timer 1 counted since the last interrupt? */
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158 ulDifference = ulLastCount - ulCurrentCount;
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160 /* Is this the largest difference we have measured yet? */
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161 if( ulDifference > ulMaxDifference )
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163 ulMaxDifference = ulDifference;
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164 ulMaxJitter = ulMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
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168 ulLastCount = ulCurrentCount;
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170 /* Keep a count of the total number of 20KHz ticks. This is used by the
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171 run time stats functionality to calculate how much CPU time is used by
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173 ulHighFrequencyTimerTicks++;
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