2 FreeRTOS V7.5.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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6 ***************************************************************************
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8 * FreeRTOS provides completely free yet professionally developed, *
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9 * robust, strictly quality controlled, supported, and cross *
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10 * platform software that has become a de facto standard. *
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12 * Help yourself get started quickly and support the FreeRTOS *
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13 * project by purchasing a FreeRTOS tutorial book, reference *
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14 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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18 ***************************************************************************
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20 This file is part of the FreeRTOS distribution.
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22 FreeRTOS is free software; you can redistribute it and/or modify it under
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23 the terms of the GNU General Public License (version 2) as published by the
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24 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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26 >>! NOTE: The modification to the GPL is included to allow you to distribute
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27 >>! a combined work that includes FreeRTOS without being obliged to provide
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28 >>! the source code for proprietary components outside of the FreeRTOS
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31 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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32 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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33 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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34 link: http://www.freertos.org/a00114.html
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38 ***************************************************************************
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40 * Having a problem? Start by reading the FAQ "My application does *
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41 * not run, what could be wrong?" *
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43 * http://www.FreeRTOS.org/FAQHelp.html *
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45 ***************************************************************************
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47 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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48 license and Real Time Engineers Ltd. contact details.
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50 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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51 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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52 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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54 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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55 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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56 licenses offer ticketed support, indemnification and middleware.
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58 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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59 engineered and independently SIL3 certified version for use in safety and
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60 mission critical applications that require provable dependability.
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66 * High frequency 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 /* Hardware specifics. */
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73 #include "iodefine.h"
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75 /* The set frequency of the interrupt. Deviations from this are measured as
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77 #define timerINTERRUPT_FREQUENCY ( 20000UL )
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79 /* The expected time between each of the timer interrupts - if the jitter was
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81 #define timerEXPECTED_DIFFERENCE_VALUE ( ( unsigned short ) ( ( configPERIPHERAL_CLOCK_HZ / 8UL ) / timerINTERRUPT_FREQUENCY ) )
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83 /* The highest available interrupt priority. */
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84 #define timerHIGHEST_PRIORITY ( 15 )
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87 #define timerTIMER_3_COUNT_VALUE ( *( ( unsigned short * ) 0x8801a ) ) /*( CMT3.CMCNT )*/
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89 /*-----------------------------------------------------------*/
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91 /* Interrupt handler in which the jitter is measured. */
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92 static void prvTimer2IntHandler( void );
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94 /* Stores the value of the maximum recorded jitter between interrupts. This is
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95 displayed on one of the served web pages. */
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96 volatile unsigned short usMaxJitter = 0;
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98 /* Counts the number of high frequency interrupts - used to generate the run
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100 volatile unsigned long ulHighFrequencyTickCount = 0UL;
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102 /*-----------------------------------------------------------*/
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104 void vSetupHighFrequencyTimer( void )
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106 /* Timer CMT2 is used to generate the interrupts, and CMT3 is used
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107 to measure the jitter. */
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109 /* Enable compare match timer 2 and 3. */
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113 /* Interrupt on compare match. */
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114 CMT2.CMCR.BIT.CMIE = 1;
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116 /* Set the compare match value. */
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117 CMT2.CMCOR = ( unsigned short ) ( ( ( configPERIPHERAL_CLOCK_HZ / timerINTERRUPT_FREQUENCY ) -1 ) / 8 );
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119 /* Divide the PCLK by 8. */
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120 CMT2.CMCR.BIT.CKS = 0;
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121 CMT3.CMCR.BIT.CKS = 0;
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123 /* Enable the interrupt... */
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124 _IEN( _CMT2_CMI2 ) = 1;
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126 /* ...and set its priority to the maximum possible, this is above the priority
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127 set by configMAX_SYSCALL_INTERRUPT_PRIORITY so will nest. */
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128 _IPR( _CMT2_CMI2 ) = timerHIGHEST_PRIORITY;
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130 /* Start the timers. */
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131 CMT.CMSTR1.BIT.STR2 = 1;
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132 CMT.CMSTR1.BIT.STR3 = 1;
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134 /*-----------------------------------------------------------*/
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136 #pragma interrupt ( prvTimer2IntHandler( vect = _VECT( _CMT2_CMI2 ), enable ) )
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137 static void prvTimer2IntHandler( void )
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139 volatile unsigned short usCurrentCount;
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140 static unsigned short usMaxCount = 0;
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141 static unsigned long ulErrorCount = 0UL;
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143 /* We use the timer 1 counter value to measure the clock cycles between
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144 the timer 0 interrupts. First stop the clock. */
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145 CMT.CMSTR1.BIT.STR3 = 0;
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148 usCurrentCount = timerTIMER_3_COUNT_VALUE;
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150 /* Is this the largest count we have measured yet? */
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151 if( usCurrentCount > usMaxCount )
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153 if( usCurrentCount > timerEXPECTED_DIFFERENCE_VALUE )
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155 usMaxJitter = usCurrentCount - timerEXPECTED_DIFFERENCE_VALUE;
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159 /* This should not happen! */
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163 usMaxCount = usCurrentCount;
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166 /* Used to generate the run time stats. */
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167 ulHighFrequencyTickCount++;
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169 /* Clear the timer. */
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170 timerTIMER_3_COUNT_VALUE = 0;
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172 /* Then start the clock again. */
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173 CMT.CMSTR1.BIT.STR3 = 1;
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