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 "hw_ints.h"
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55 #include "hw_memmap.h"
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56 #include "hw_types.h"
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57 #include "interrupt.h"
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59 #include "lmi_timer.h"
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60 #include "hw_timer.h"
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62 /* The set frequency of the interrupt. Deviations from this are measured as
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64 #define timerINTERRUPT_FREQUENCY ( 20000UL )
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66 /* The expected time between each of the timer interrupts - if the jitter was
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68 #define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
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70 /* The highest available interrupt priority. */
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71 #define timerHIGHEST_PRIORITY ( 0 )
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74 #define timerMAX_32BIT_VALUE ( 0xffffffffUL )
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75 #define timerTIMER_1_COUNT_VALUE ( * ( ( volatile unsigned long * ) ( ( unsigned portLONG ) TIMER1_BASE + 0x48UL ) ) )
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77 /*-----------------------------------------------------------*/
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79 /* Interrupt handler in which the jitter is measured. */
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80 void Timer0IntHandler( void );
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82 /* Stores the value of the maximum recorded jitter between interrupts. */
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83 volatile unsigned portLONG ulMaxJitter = 0;
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85 /*-----------------------------------------------------------*/
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87 void vSetupHighFrequencyTimer( void )
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89 unsigned long ulFrequency;
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91 /* Timer zero is used to generate the interrupts, and timer 1 is used
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92 to measure the jitter. */
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93 SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER0 );
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94 SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER1 );
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95 TimerConfigure( TIMER0_BASE, TIMER_CFG_32_BIT_PER );
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96 TimerConfigure( TIMER1_BASE, TIMER_CFG_32_BIT_PER );
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98 /* Set the timer interrupt to be above the kernel - highest. */
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99 IntPrioritySet( INT_TIMER0A, timerHIGHEST_PRIORITY );
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101 /* Just used to measure time. */
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102 TimerLoadSet(TIMER1_BASE, TIMER_A, timerMAX_32BIT_VALUE );
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104 /* Ensure interrupts do not start until the scheduler is running. */
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105 portDISABLE_INTERRUPTS();
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107 /* The rate at which the timer will interrupt. */
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108 ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
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109 TimerLoadSet( TIMER0_BASE, TIMER_A, ulFrequency );
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110 IntEnable( INT_TIMER0A );
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111 TimerIntEnable( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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113 /* Enable both timers. */
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114 TimerEnable( TIMER0_BASE, TIMER_A );
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115 TimerEnable( TIMER1_BASE, TIMER_A );
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117 /*-----------------------------------------------------------*/
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119 void Timer0IntHandler( void )
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121 unsigned portLONG ulDifference;
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122 volatile unsigned portLONG ulCurrentCount;
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123 static unsigned portLONG ulMaxDifference = 0, ulLastCount = 0;
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125 /* We use the timer 1 counter value to measure the clock cycles between
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126 the timer 0 interrupts. */
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127 ulCurrentCount = timerTIMER_1_COUNT_VALUE;
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129 TimerIntClear( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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131 if( ulCurrentCount < ulLastCount )
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133 /* How many times has timer 1 counted since the last interrupt? */
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134 ulDifference = ulLastCount - ulCurrentCount;
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136 /* Is this the largest difference we have measured yet? */
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137 if( ulDifference > ulMaxDifference )
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139 ulMaxDifference = ulDifference;
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140 ulMaxJitter = ulMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
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144 ulLastCount = ulCurrentCount;
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