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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70 * High frequency timer test as described in main.c.
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73 /* Scheduler includes. */
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74 #include "FreeRTOS.h"
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76 /* Hardware specifics. */
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77 #include "iodefine.h"
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79 /* The set frequency of the interrupt. Deviations from this are measured as
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81 #define timerINTERRUPT_FREQUENCY ( 20000UL )
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83 /* The expected time between each of the timer interrupts - if the jitter was
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85 #define timerEXPECTED_DIFFERENCE_VALUE ( ( unsigned short ) ( ( configPERIPHERAL_CLOCK_HZ / 8UL ) / timerINTERRUPT_FREQUENCY ) )
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87 /* The highest available interrupt priority. */
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88 #define timerHIGHEST_PRIORITY ( 15 )
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91 #define timerTIMER_3_COUNT_VALUE ( *( ( unsigned short * ) 0x8801a ) ) /*( CMT3.CMCNT )*/
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93 /*-----------------------------------------------------------*/
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95 /* Interrupt handler in which the jitter is measured. */
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96 static void prvTimer2IntHandler( void );
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98 /* Stores the value of the maximum recorded jitter between interrupts. This is
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99 displayed on one of the served web pages. */
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100 volatile unsigned short usMaxJitter = 0;
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102 /* Counts the number of high frequency interrupts - used to generate the run
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104 volatile unsigned long ulHighFrequencyTickCount = 0UL;
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106 /*-----------------------------------------------------------*/
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108 void vSetupHighFrequencyTimer( void )
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110 /* Timer CMT2 is used to generate the interrupts, and CMT3 is used
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111 to measure the jitter. */
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113 /* Enable compare match timer 2 and 3. */
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117 /* Interrupt on compare match. */
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118 CMT2.CMCR.BIT.CMIE = 1;
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120 /* Set the compare match value. */
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121 CMT2.CMCOR = ( unsigned short ) ( ( ( configPERIPHERAL_CLOCK_HZ / timerINTERRUPT_FREQUENCY ) -1 ) / 8 );
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123 /* Divide the PCLK by 8. */
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124 CMT2.CMCR.BIT.CKS = 0;
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125 CMT3.CMCR.BIT.CKS = 0;
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127 /* Enable the interrupt... */
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128 _IEN( _CMT2_CMI2 ) = 1;
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130 /* ...and set its priority to the maximum possible, this is above the priority
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131 set by configMAX_SYSCALL_INTERRUPT_PRIORITY so will nest. */
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132 _IPR( _CMT2_CMI2 ) = timerHIGHEST_PRIORITY;
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134 /* Start the timers. */
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135 CMT.CMSTR1.BIT.STR2 = 1;
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136 CMT.CMSTR1.BIT.STR3 = 1;
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138 /*-----------------------------------------------------------*/
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140 #pragma interrupt ( prvTimer2IntHandler( vect = _VECT( _CMT2_CMI2 ), enable ) )
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141 static void prvTimer2IntHandler( void )
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143 volatile unsigned short usCurrentCount;
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144 static unsigned short usMaxCount = 0;
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145 static unsigned long ulErrorCount = 0UL;
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147 /* We use the timer 1 counter value to measure the clock cycles between
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148 the timer 0 interrupts. First stop the clock. */
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149 CMT.CMSTR1.BIT.STR3 = 0;
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152 usCurrentCount = timerTIMER_3_COUNT_VALUE;
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154 /* Is this the largest count we have measured yet? */
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155 if( usCurrentCount > usMaxCount )
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157 if( usCurrentCount > timerEXPECTED_DIFFERENCE_VALUE )
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159 usMaxJitter = usCurrentCount - timerEXPECTED_DIFFERENCE_VALUE;
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163 /* This should not happen! */
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167 usMaxCount = usCurrentCount;
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170 /* Used to generate the run time stats. */
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171 ulHighFrequencyTickCount++;
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173 /* Clear the timer. */
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174 timerTIMER_3_COUNT_VALUE = 0;
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176 /* Then start the clock again. */
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177 CMT.CMSTR1.BIT.STR3 = 1;
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