2 FreeRTOS.org V5.3.1 - Copyright (C) 2003-2009 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License (version 2) as published
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8 by the 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.org without being obliged to provide
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11 the source code for any proprietary components. Alternative commercial
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12 license and support terms are also available upon request. See the
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13 licensing section of http://www.FreeRTOS.org for full details.
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15 FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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20 You should have received a copy of the GNU General Public License along
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21 with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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22 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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25 ***************************************************************************
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27 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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29 * This is a concise, step by step, 'hands on' guide that describes both *
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30 * general multitasking concepts and FreeRTOS specifics. It presents and *
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31 * explains numerous examples that are written using the FreeRTOS API. *
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32 * Full source code for all the examples is provided in an accompanying *
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35 ***************************************************************************
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39 Please ensure to read the configuration and relevant port sections of the
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40 online documentation.
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42 http://www.FreeRTOS.org - Documentation, latest information, license and
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45 http://www.SafeRTOS.com - A version that is certified for use in safety
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48 http://www.OpenRTOS.com - Commercial support, development, porting,
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49 licensing and training services.
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52 /* High speed timer test as described in main.c. */
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54 /* Scheduler includes. */
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55 #include "FreeRTOS.h"
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57 /* Library includes. */
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58 #include "hw_ints.h"
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59 #include "hw_memmap.h"
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60 #include "hw_types.h"
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61 #include "interrupt.h"
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63 #include "lmi_timer.h"
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64 #include "hw_timer.h"
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66 /* The set frequency of the interrupt. Deviations from this are measured as
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68 #define timerINTERRUPT_FREQUENCY ( 20000UL )
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70 /* The expected time between each of the timer interrupts - if the jitter was
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72 #define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
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74 /* The highest available interrupt priority. */
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75 #define timerHIGHEST_PRIORITY ( 0 )
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78 #define timerMAX_32BIT_VALUE ( 0xffffffffUL )
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79 #define timerTIMER_1_COUNT_VALUE ( * ( ( volatile unsigned long * ) ( ( unsigned portLONG ) TIMER1_BASE + 0x48UL ) ) )
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81 /*-----------------------------------------------------------*/
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83 /* Interrupt handler in which the jitter is measured. */
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84 void Timer0IntHandler( void );
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86 /* Stores the value of the maximum recorded jitter between interrupts. */
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87 volatile unsigned portLONG ulMaxJitter = 0;
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89 /*-----------------------------------------------------------*/
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91 void vSetupHighFrequencyTimer( void )
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93 unsigned long ulFrequency;
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95 /* Timer zero is used to generate the interrupts, and timer 1 is used
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96 to measure the jitter. */
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97 SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER0 );
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98 SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER1 );
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99 TimerConfigure( TIMER0_BASE, TIMER_CFG_32_BIT_PER );
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100 TimerConfigure( TIMER1_BASE, TIMER_CFG_32_BIT_PER );
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102 /* Set the timer interrupt to be above the kernel - highest. */
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103 IntPrioritySet( INT_TIMER0A, timerHIGHEST_PRIORITY );
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105 /* Just used to measure time. */
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106 TimerLoadSet(TIMER1_BASE, TIMER_A, timerMAX_32BIT_VALUE );
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108 /* Ensure interrupts do not start until the scheduler is running. */
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109 portDISABLE_INTERRUPTS();
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111 /* The rate at which the timer will interrupt. */
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112 ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
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113 TimerLoadSet( TIMER0_BASE, TIMER_A, ulFrequency );
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114 IntEnable( INT_TIMER0A );
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115 TimerIntEnable( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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117 /* Enable both timers. */
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118 TimerEnable( TIMER0_BASE, TIMER_A );
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119 TimerEnable( TIMER1_BASE, TIMER_A );
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121 /*-----------------------------------------------------------*/
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123 void Timer0IntHandler( void )
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125 unsigned portLONG ulDifference;
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126 volatile unsigned portLONG ulCurrentCount;
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127 static unsigned portLONG ulMaxDifference = 0, ulLastCount = 0;
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129 /* We use the timer 1 counter value to measure the clock cycles between
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130 the timer 0 interrupts. */
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131 ulCurrentCount = timerTIMER_1_COUNT_VALUE;
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133 TimerIntClear( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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135 if( ulCurrentCount < ulLastCount )
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137 /* How many times has timer 1 counted since the last interrupt? */
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138 ulDifference = ulLastCount - ulCurrentCount;
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140 /* Is this the largest difference we have measured yet? */
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141 if( ulDifference > ulMaxDifference )
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143 ulMaxDifference = ulDifference;
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144 ulMaxJitter = ulMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
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148 ulLastCount = ulCurrentCount;
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