2 FreeRTOS V7.1.1 - 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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68 * This file defines the button push task and ISR as described at the top of
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69 * main.c. The ISR is called from a wrapper function defined in ButtonISR.s26.
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72 /* Kernel includes. */
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73 #include "FreeRTOS.h"
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77 /* The LED output used by the button push task. */
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78 #define butLED1 P7_bit.no7
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80 /* A short delay used for button debouncing. */
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81 #define butDEBOUNCE_DELAY ( 200 / portTICK_RATE_MS )
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83 /* The semaphore used to synchronise the button push task with the interrupt. */
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84 static xSemaphoreHandle xButtonSemaphore;
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87 * The definition of the button task itself. See the comments at the top of
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90 void vButtonTask( void *pvParameters )
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92 /* Ensure the semaphore is created before it gets used. */
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93 vSemaphoreCreateBinary( xButtonSemaphore );
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97 /* Block on the semaphore to wait for an interrupt event. The semaphore
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98 is 'given' from vButtonISRHandler() below. Using portMAX_DELAY as the
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99 block time will cause the task to block indefinitely provided
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100 INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h. */
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101 xSemaphoreTake( xButtonSemaphore, portMAX_DELAY );
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103 /* The button must have been pushed for this line to be executed.
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104 Simply toggle the LED. */
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105 butLED1 = !butLED1;
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107 /* Wait a short time then clear any pending button pushes as a crude
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108 method of debouncing the switch. xSemaphoreTake() uses a block time of
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109 zero this time so it returns immediately rather than waiting for the
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110 interrupt to occur. */
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111 vTaskDelay( butDEBOUNCE_DELAY );
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112 xSemaphoreTake( xButtonSemaphore, 0 );
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115 /*-----------------------------------------------------------*/
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118 * The C portion of the interrupt handler. Interrupts are triggered by pushing
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119 * the button on the target board. This interrupt can cause a context switch
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120 * so has an assembly file wrapper defined within ButtonISR.s26.
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122 void vButtonISRHandler( void )
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124 short sHigherPriorityTaskWoken = pdFALSE;
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126 /* 'Give' the semaphore to unblock the button task. */
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127 xSemaphoreGiveFromISR( xButtonSemaphore, &sHigherPriorityTaskWoken );
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129 /* If giving the semaphore unblocked a task, and the unblocked task has a
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130 priority that is higher than the currently running task, then
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131 sHigherPriorityTaskWoken will have been set to pdTRUE. Passing a pdTRUE
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132 value to portYIELD_FROM_ISR() will cause this interrupt to return directly
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133 to the higher priority unblocked task. */
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134 portYIELD_FROM_ISR( sHigherPriorityTaskWoken );
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136 /*-----------------------------------------------------------*/
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