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 "hw_ints.h"
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74 #include "hw_memmap.h"
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75 #include "hw_types.h"
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76 #include "interrupt.h"
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78 #include "lmi_timer.h"
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79 #include "hw_timer.h"
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81 /* The set frequency of the interrupt. Deviations from this are measured as
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83 #define timerINTERRUPT_FREQUENCY ( 20000UL )
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85 /* The expected time between each of the timer interrupts - if the jitter was
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87 #define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
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89 /* The highest available interrupt priority. */
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90 #define timerHIGHEST_PRIORITY ( 0 )
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93 #define timerMAX_32BIT_VALUE ( 0xffffffffUL )
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94 #define timerTIMER_1_COUNT_VALUE ( * ( ( volatile unsigned long * ) ( ( unsigned portLONG ) TIMER1_BASE + 0x48UL ) ) )
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96 /*-----------------------------------------------------------*/
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98 /* Interrupt handler in which the jitter is measured. */
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99 void Timer0IntHandler( void );
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101 /* Stores the value of the maximum recorded jitter between interrupts. */
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102 volatile unsigned portLONG ulMaxJitter = 0;
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104 /*-----------------------------------------------------------*/
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106 void vSetupHighFrequencyTimer( void )
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108 unsigned long ulFrequency;
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110 /* Timer zero is used to generate the interrupts, and timer 1 is used
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111 to measure the jitter. */
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112 SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER0 );
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113 SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER1 );
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114 TimerConfigure( TIMER0_BASE, TIMER_CFG_32_BIT_PER );
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115 TimerConfigure( TIMER1_BASE, TIMER_CFG_32_BIT_PER );
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117 /* Set the timer interrupt to be above the kernel - highest. */
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118 IntPrioritySet( INT_TIMER0A, timerHIGHEST_PRIORITY );
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120 /* Just used to measure time. */
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121 TimerLoadSet(TIMER1_BASE, TIMER_A, timerMAX_32BIT_VALUE );
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123 /* Ensure interrupts do not start until the scheduler is running. */
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124 portDISABLE_INTERRUPTS();
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126 /* The rate at which the timer will interrupt. */
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127 ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
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128 TimerLoadSet( TIMER0_BASE, TIMER_A, ulFrequency );
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129 IntEnable( INT_TIMER0A );
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130 TimerIntEnable( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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132 /* Enable both timers. */
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133 TimerEnable( TIMER0_BASE, TIMER_A );
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134 TimerEnable( TIMER1_BASE, TIMER_A );
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136 /*-----------------------------------------------------------*/
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138 void Timer0IntHandler( void )
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140 unsigned portLONG ulDifference;
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141 volatile unsigned portLONG ulCurrentCount;
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142 static unsigned portLONG ulMaxDifference = 0, ulLastCount = 0;
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144 /* We use the timer 1 counter value to measure the clock cycles between
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145 the timer 0 interrupts. */
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146 ulCurrentCount = timerTIMER_1_COUNT_VALUE;
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148 TimerIntClear( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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150 if( ulCurrentCount < ulLastCount )
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152 /* How many times has timer 1 counted since the last interrupt? */
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153 ulDifference = ulLastCount - ulCurrentCount;
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155 /* Is this the largest difference we have measured yet? */
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156 if( ulDifference > ulMaxDifference )
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158 ulMaxDifference = ulDifference;
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159 ulMaxJitter = ulMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
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163 ulLastCount = ulCurrentCount;
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