2 FreeRTOS V7.4.0 - Copyright (C) 2013 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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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not itcan be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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76 * The first test creates three tasks - two counter tasks (one continuous count
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77 * and one limited count) and one controller. A "count" variable is shared
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78 * between all three tasks. The two counter tasks should never be in a "ready"
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79 * state at the same time. The controller task runs at the same priority as
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80 * the continuous count task, and at a lower priority than the limited count
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83 * One counter task loops indefinitely, incrementing the shared count variable
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84 * on each iteration. To ensure it has exclusive access to the variable it
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85 * raises it's priority above that of the controller task before each
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86 * increment, lowering it again to it's original priority before starting the
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89 * The other counter task increments the shared count variable on each
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90 * iteration of it's loop until the count has reached a limit of 0xff - at
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91 * which point it suspends itself. It will not start a new loop until the
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92 * controller task has made it "ready" again by calling vTaskResume ().
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93 * This second counter task operates at a higher priority than controller
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94 * task so does not need to worry about mutual exclusion of the counter
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97 * The controller task is in two sections. The first section controls and
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98 * monitors the continuous count task. When this section is operational the
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99 * limited count task is suspended. Likewise, the second section controls
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100 * and monitors the limited count task. When this section is operational the
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101 * continuous count task is suspended.
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103 * In the first section the controller task first takes a copy of the shared
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104 * count variable. To ensure mutual exclusion on the count variable it
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105 * suspends the continuous count task, resuming it again when the copy has been
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106 * taken. The controller task then sleeps for a fixed period - during which
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107 * the continuous count task will execute and increment the shared variable.
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108 * When the controller task wakes it checks that the continuous count task
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109 * has executed by comparing the copy of the shared variable with its current
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110 * value. This time, to ensure mutual exclusion, the scheduler itself is
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111 * suspended with a call to vTaskSuspendAll (). This is for demonstration
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112 * purposes only and is not a recommended technique due to its inefficiency.
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114 * After a fixed number of iterations the controller task suspends the
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115 * continuous count task, and moves on to its second section.
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117 * At the start of the second section the shared variable is cleared to zero.
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118 * The limited count task is then woken from it's suspension by a call to
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119 * vTaskResume (). As this counter task operates at a higher priority than
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120 * the controller task the controller task should not run again until the
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121 * shared variable has been counted up to the limited value causing the counter
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122 * task to suspend itself. The next line after vTaskResume () is therefore
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123 * a check on the shared variable to ensure everything is as expected.
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126 * The second test consists of a couple of very simple tasks that post onto a
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127 * queue while the scheduler is suspended. This test was added to test parts
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128 * of the scheduler not exercised by the first test.
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132 #include <stdlib.h>
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134 /* Scheduler include files. */
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135 #include "FreeRTOS.h"
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137 #include "semphr.h"
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139 /* Demo app include files. */
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140 #include "dynamic.h"
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142 /* Function that implements the "limited count" task as described above. */
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143 static portTASK_FUNCTION_PROTO( vLimitedIncrementTask, pvParameters );
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145 /* Function that implements the "continuous count" task as described above. */
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146 static portTASK_FUNCTION_PROTO( vContinuousIncrementTask, pvParameters );
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148 /* Function that implements the controller task as described above. */
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149 static portTASK_FUNCTION_PROTO( vCounterControlTask, pvParameters );
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151 static portTASK_FUNCTION_PROTO( vQueueReceiveWhenSuspendedTask, pvParameters );
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152 static portTASK_FUNCTION_PROTO( vQueueSendWhenSuspendedTask, pvParameters );
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154 /* Demo task specific constants. */
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155 #define priSTACK_SIZE ( configMINIMAL_STACK_SIZE )
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156 #define priSLEEP_TIME ( ( portTickType ) 128 / portTICK_RATE_MS )
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157 #define priLOOPS ( 5 )
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158 #define priMAX_COUNT ( ( unsigned long ) 0xff )
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159 #define priNO_BLOCK ( ( portTickType ) 0 )
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160 #define priSUSPENDED_QUEUE_LENGTH ( 1 )
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162 /*-----------------------------------------------------------*/
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164 /* Handles to the two counter tasks. These could be passed in as parameters
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165 to the controller task to prevent them having to be file scope. */
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166 static xTaskHandle xContinousIncrementHandle, xLimitedIncrementHandle;
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168 /* The shared counter variable. This is passed in as a parameter to the two
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169 counter variables for demonstration purposes. */
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170 static unsigned long ulCounter;
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172 /* Variables used to check that the tasks are still operating without error.
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173 Each complete iteration of the controller task increments this variable
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174 provided no errors have been found. The variable maintaining the same value
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175 is therefore indication of an error. */
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176 static volatile unsigned short usCheckVariable = ( unsigned short ) 0;
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177 static volatile portBASE_TYPE xSuspendedQueueSendError = pdFALSE;
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178 static volatile portBASE_TYPE xSuspendedQueueReceiveError = pdFALSE;
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180 /* Queue used by the second test. */
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181 static xQueueHandle xSuspendedTestQueue;
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183 /*-----------------------------------------------------------*/
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185 * Start the three tasks as described at the top of the file.
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186 * Note that the limited count task is given a higher priority.
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188 void vStartDynamicPriorityTasks( void )
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190 xSuspendedTestQueue = xQueueCreate( priSUSPENDED_QUEUE_LENGTH, sizeof( unsigned long ) );
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192 /* vQueueAddToRegistry() adds the queue to the queue registry, if one is
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193 in use. The queue registry is provided as a means for kernel aware
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194 debuggers to locate queues and has no purpose if a kernel aware debugger
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195 is not being used. The call to vQueueAddToRegistry() will be removed
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196 by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is
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197 defined to be less than 1. */
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198 vQueueAddToRegistry( xSuspendedTestQueue, ( signed char * ) "Suspended_Test_Queue" );
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200 xTaskCreate( vContinuousIncrementTask, ( signed char * ) "CNT_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY, &xContinousIncrementHandle );
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201 xTaskCreate( vLimitedIncrementTask, ( signed char * ) "LIM_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY + 1, &xLimitedIncrementHandle );
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202 xTaskCreate( vCounterControlTask, ( signed char * ) "C_CTRL", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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203 xTaskCreate( vQueueSendWhenSuspendedTask, ( signed char * ) "SUSP_TX", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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204 xTaskCreate( vQueueReceiveWhenSuspendedTask, ( signed char * ) "SUSP_RX", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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206 /*-----------------------------------------------------------*/
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209 * Just loops around incrementing the shared variable until the limit has been
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210 * reached. Once the limit has been reached it suspends itself.
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212 static portTASK_FUNCTION( vLimitedIncrementTask, pvParameters )
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214 unsigned long *pulCounter;
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216 /* Take a pointer to the shared variable from the parameters passed into
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218 pulCounter = ( unsigned long * ) pvParameters;
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220 /* This will run before the control task, so the first thing it does is
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221 suspend - the control task will resume it when ready. */
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222 vTaskSuspend( NULL );
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226 /* Just count up to a value then suspend. */
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229 if( *pulCounter >= priMAX_COUNT )
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231 vTaskSuspend( NULL );
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235 /*-----------------------------------------------------------*/
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238 * Just keep counting the shared variable up. The control task will suspend
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239 * this task when it wants.
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241 static portTASK_FUNCTION( vContinuousIncrementTask, pvParameters )
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243 unsigned long *pulCounter;
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244 unsigned portBASE_TYPE uxOurPriority;
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246 /* Take a pointer to the shared variable from the parameters passed into
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248 pulCounter = ( unsigned long * ) pvParameters;
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250 /* Query our priority so we can raise it when exclusive access to the
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251 shared variable is required. */
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252 uxOurPriority = uxTaskPriorityGet( NULL );
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256 /* Raise our priority above the controller task to ensure a context
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257 switch does not occur while we are accessing this variable. */
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258 vTaskPrioritySet( NULL, uxOurPriority + 1 );
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260 vTaskPrioritySet( NULL, uxOurPriority );
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263 /*-----------------------------------------------------------*/
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266 * Controller task as described above.
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268 static portTASK_FUNCTION( vCounterControlTask, pvParameters )
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270 unsigned long ulLastCounter;
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272 short sError = pdFALSE;
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274 /* Just to stop warning messages. */
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275 ( void ) pvParameters;
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279 /* Start with the counter at zero. */
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280 ulCounter = ( unsigned long ) 0;
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282 /* First section : */
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284 /* Check the continuous count task is running. */
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285 for( sLoops = 0; sLoops < priLOOPS; sLoops++ )
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287 /* Suspend the continuous count task so we can take a mirror of the
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288 shared variable without risk of corruption. */
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289 vTaskSuspend( xContinousIncrementHandle );
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290 ulLastCounter = ulCounter;
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291 vTaskResume( xContinousIncrementHandle );
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293 /* Now delay to ensure the other task has processor time. */
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294 vTaskDelay( priSLEEP_TIME );
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296 /* Check the shared variable again. This time to ensure mutual
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297 exclusion the whole scheduler will be locked. This is just for
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301 if( ulLastCounter == ulCounter )
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303 /* The shared variable has not changed. There is a problem
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304 with the continuous count task so flag an error. */
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312 /* Second section: */
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314 /* Suspend the continuous counter task so it stops accessing the shared variable. */
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315 vTaskSuspend( xContinousIncrementHandle );
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317 /* Reset the variable. */
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318 ulCounter = ( unsigned long ) 0;
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320 /* Resume the limited count task which has a higher priority than us.
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321 We should therefore not return from this call until the limited count
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322 task has suspended itself with a known value in the counter variable. */
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323 vTaskResume( xLimitedIncrementHandle );
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325 /* Does the counter variable have the expected value? */
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326 if( ulCounter != priMAX_COUNT )
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331 if( sError == pdFALSE )
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333 /* If no errors have occurred then increment the check variable. */
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334 portENTER_CRITICAL();
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336 portEXIT_CRITICAL();
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339 /* Resume the continuous count task and do it all again. */
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340 vTaskResume( xContinousIncrementHandle );
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343 /*-----------------------------------------------------------*/
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345 static portTASK_FUNCTION( vQueueSendWhenSuspendedTask, pvParameters )
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347 static unsigned long ulValueToSend = ( unsigned long ) 0;
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349 /* Just to stop warning messages. */
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350 ( void ) pvParameters;
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356 /* We must not block while the scheduler is suspended! */
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357 if( xQueueSend( xSuspendedTestQueue, ( void * ) &ulValueToSend, priNO_BLOCK ) != pdTRUE )
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359 xSuspendedQueueSendError = pdTRUE;
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364 vTaskDelay( priSLEEP_TIME );
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369 /*-----------------------------------------------------------*/
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371 static portTASK_FUNCTION( vQueueReceiveWhenSuspendedTask, pvParameters )
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373 static unsigned long ulExpectedValue = ( unsigned long ) 0, ulReceivedValue;
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374 portBASE_TYPE xGotValue;
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376 /* Just to stop warning messages. */
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377 ( void ) pvParameters;
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383 /* Suspending the scheduler here is fairly pointless and
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384 undesirable for a normal application. It is done here purely
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385 to test the scheduler. The inner xTaskResumeAll() should
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386 never return pdTRUE as the scheduler is still locked by the
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392 xGotValue = xQueueReceive( xSuspendedTestQueue, ( void * ) &ulReceivedValue, priNO_BLOCK );
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394 if( xTaskResumeAll() )
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396 xSuspendedQueueReceiveError = pdTRUE;
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401 #if configUSE_PREEMPTION == 0
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407 } while( xGotValue == pdFALSE );
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409 if( ulReceivedValue != ulExpectedValue )
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411 xSuspendedQueueReceiveError = pdTRUE;
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417 /*-----------------------------------------------------------*/
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419 /* Called to check that all the created tasks are still running without error. */
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420 portBASE_TYPE xAreDynamicPriorityTasksStillRunning( void )
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422 /* Keep a history of the check variables so we know if it has been incremented
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423 since the last call. */
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424 static unsigned short usLastTaskCheck = ( unsigned short ) 0;
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425 portBASE_TYPE xReturn = pdTRUE;
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427 /* Check the tasks are still running by ensuring the check variable
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428 is still incrementing. */
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430 if( usCheckVariable == usLastTaskCheck )
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432 /* The check has not incremented so an error exists. */
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436 if( xSuspendedQueueSendError == pdTRUE )
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441 if( xSuspendedQueueReceiveError == pdTRUE )
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446 usLastTaskCheck = usCheckVariable;
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