2 FreeRTOS V7.5.0 - 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 * The first test creates three tasks - two counter tasks (one continuous count
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67 * and one limited count) and one controller. A "count" variable is shared
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68 * between all three tasks. The two counter tasks should never be in a "ready"
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69 * state at the same time. The controller task runs at the same priority as
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70 * the continuous count task, and at a lower priority than the limited count
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73 * One counter task loops indefinitely, incrementing the shared count variable
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74 * on each iteration. To ensure it has exclusive access to the variable it
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75 * raises it's priority above that of the controller task before each
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76 * increment, lowering it again to it's original priority before starting the
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79 * The other counter task increments the shared count variable on each
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80 * iteration of it's loop until the count has reached a limit of 0xff - at
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81 * which point it suspends itself. It will not start a new loop until the
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82 * controller task has made it "ready" again by calling vTaskResume ().
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83 * This second counter task operates at a higher priority than controller
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84 * task so does not need to worry about mutual exclusion of the counter
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87 * The controller task is in two sections. The first section controls and
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88 * monitors the continuous count task. When this section is operational the
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89 * limited count task is suspended. Likewise, the second section controls
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90 * and monitors the limited count task. When this section is operational the
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91 * continuous count task is suspended.
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93 * In the first section the controller task first takes a copy of the shared
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94 * count variable. To ensure mutual exclusion on the count variable it
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95 * suspends the continuous count task, resuming it again when the copy has been
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96 * taken. The controller task then sleeps for a fixed period - during which
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97 * the continuous count task will execute and increment the shared variable.
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98 * When the controller task wakes it checks that the continuous count task
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99 * has executed by comparing the copy of the shared variable with its current
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100 * value. This time, to ensure mutual exclusion, the scheduler itself is
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101 * suspended with a call to vTaskSuspendAll (). This is for demonstration
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102 * purposes only and is not a recommended technique due to its inefficiency.
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104 * After a fixed number of iterations the controller task suspends the
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105 * continuous count task, and moves on to its second section.
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107 * At the start of the second section the shared variable is cleared to zero.
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108 * The limited count task is then woken from it's suspension by a call to
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109 * vTaskResume (). As this counter task operates at a higher priority than
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110 * the controller task the controller task should not run again until the
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111 * shared variable has been counted up to the limited value causing the counter
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112 * task to suspend itself. The next line after vTaskResume () is therefore
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113 * a check on the shared variable to ensure everything is as expected.
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116 * The second test consists of a couple of very simple tasks that post onto a
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117 * queue while the scheduler is suspended. This test was added to test parts
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118 * of the scheduler not exercised by the first test.
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121 * The final set of two tasks implements a third test. This simply raises the
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122 * priority of a task while the scheduler is suspended. Again this test was
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123 * added to exercise parts of the code not covered by the first test.
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125 * \page Priorities dynamic.c
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126 * \ingroup DemoFiles
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131 Changes from V2.0.0
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133 + Delay periods are now specified using variables and constants of
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134 portTickType rather than unsigned long.
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135 + Added a second, simple test that uses the functions
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136 vQueueReceiveWhenSuspendedTask() and vQueueSendWhenSuspendedTask().
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138 Changes from V3.1.1
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140 + Added a third simple test that uses the vTaskPrioritySet() function
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141 while the scheduler is suspended.
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142 + Modified the controller task slightly to test the calling of
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143 vTaskResumeAll() while the scheduler is suspended.
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146 #include <stdlib.h>
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148 /* Scheduler include files. */
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149 #include "FreeRTOS.h"
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151 #include "semphr.h"
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153 /* Demo app include files. */
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154 #include "dynamic.h"
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157 /* Function that implements the "limited count" task as described above. */
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158 static void vLimitedIncrementTask( void * pvParameters );
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160 /* Function that implements the "continuous count" task as described above. */
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161 static void vContinuousIncrementTask( void * pvParameters );
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163 /* Function that implements the controller task as described above. */
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164 static void vCounterControlTask( void * pvParameters );
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166 /* The simple test functions that check sending and receiving while the
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167 scheduler is suspended. */
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168 static void vQueueReceiveWhenSuspendedTask( void *pvParameters );
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169 static void vQueueSendWhenSuspendedTask( void *pvParameters );
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171 /* The simple test functions that check raising and lowering of task priorities
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172 while the scheduler is suspended. */
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173 static void prvChangePriorityWhenSuspendedTask( void *pvParameters );
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174 static void prvChangePriorityHelperTask( void *pvParameters );
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177 /* Demo task specific constants. */
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178 #define priSTACK_SIZE ( ( unsigned short ) configMINIMAL_STACK_SIZE )
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179 #define priSLEEP_TIME ( ( portTickType ) 50 )
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180 #define priLOOPS ( 5 )
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181 #define priMAX_COUNT ( ( unsigned long ) 0xff )
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182 #define priNO_BLOCK ( ( portTickType ) 0 )
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183 #define priSUSPENDED_QUEUE_LENGTH ( 1 )
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185 /*-----------------------------------------------------------*/
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187 /* Handles to the two counter tasks. These could be passed in as parameters
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188 to the controller task to prevent them having to be file scope. */
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189 static xTaskHandle xContinuousIncrementHandle, xLimitedIncrementHandle, xChangePriorityWhenSuspendedHandle;
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191 /* The shared counter variable. This is passed in as a parameter to the two
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192 counter variables for demonstration purposes. */
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193 static unsigned long ulCounter;
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195 /* Variable used in a similar way by the test that checks the raising and
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196 lowering of task priorities while the scheduler is suspended. */
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197 static unsigned long ulPrioritySetCounter;
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199 /* Variables used to check that the tasks are still operating without error.
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200 Each complete iteration of the controller task increments this variable
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201 provided no errors have been found. The variable maintaining the same value
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202 is therefore indication of an error. */
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203 static unsigned short usCheckVariable = ( unsigned short ) 0;
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204 static portBASE_TYPE xSuspendedQueueSendError = pdFALSE;
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205 static portBASE_TYPE xSuspendedQueueReceiveError = pdFALSE;
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206 static portBASE_TYPE xPriorityRaiseWhenSuspendedError = pdFALSE;
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208 /* Queue used by the second test. */
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209 xQueueHandle xSuspendedTestQueue;
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211 /*-----------------------------------------------------------*/
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213 * Start the seven tasks as described at the top of the file.
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214 * Note that the limited count task is given a higher priority.
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216 void vStartDynamicPriorityTasks( void )
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218 xSuspendedTestQueue = xQueueCreate( priSUSPENDED_QUEUE_LENGTH, sizeof( unsigned long ) );
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219 xTaskCreate( vContinuousIncrementTask, "CONT_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY, &xContinuousIncrementHandle );
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220 xTaskCreate( vLimitedIncrementTask, "LIM_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY + 1, &xLimitedIncrementHandle );
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221 xTaskCreate( vCounterControlTask, "C_CTRL", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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222 xTaskCreate( vQueueSendWhenSuspendedTask, "SUSP_SEND", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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223 xTaskCreate( vQueueReceiveWhenSuspendedTask, "SUSP_RECV", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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224 xTaskCreate( prvChangePriorityWhenSuspendedTask, "1st_P_CHANGE", priSTACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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225 xTaskCreate( prvChangePriorityHelperTask, "2nd_P_CHANGE", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, &xChangePriorityWhenSuspendedHandle );
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227 /*-----------------------------------------------------------*/
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230 * Just loops around incrementing the shared variable until the limit has been
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231 * reached. Once the limit has been reached it suspends itself.
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233 static void vLimitedIncrementTask( void * pvParameters )
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235 unsigned long *pulCounter;
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237 /* Take a pointer to the shared variable from the parameters passed into
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239 pulCounter = ( unsigned long * ) pvParameters;
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241 /* This will run before the control task, so the first thing it does is
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242 suspend - the control task will resume it when ready. */
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243 vTaskSuspend( NULL );
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247 /* Just count up to a value then suspend. */
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248 ( *pulCounter )++;
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250 if( *pulCounter >= priMAX_COUNT )
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252 vTaskSuspend( NULL );
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256 /*-----------------------------------------------------------*/
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259 * Just keep counting the shared variable up. The control task will suspend
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260 * this task when it wants.
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262 static void vContinuousIncrementTask( void * pvParameters )
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264 unsigned long *pulCounter;
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265 unsigned portBASE_TYPE uxOurPriority;
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267 /* Take a pointer to the shared variable from the parameters passed into
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269 pulCounter = ( unsigned long * ) pvParameters;
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271 /* Query our priority so we can raise it when exclusive access to the
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272 shared variable is required. */
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273 uxOurPriority = uxTaskPriorityGet( NULL );
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277 /* Raise our priority above the controller task to ensure a context
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278 switch does not occur while we are accessing this variable. */
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279 vTaskPrioritySet( NULL, uxOurPriority + 1 );
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280 ( *pulCounter )++;
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281 vTaskPrioritySet( NULL, uxOurPriority );
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283 #if configUSE_PREEMPTION == 0
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288 /*-----------------------------------------------------------*/
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291 * Controller task as described above.
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293 static void vCounterControlTask( void * pvParameters )
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295 unsigned long ulLastCounter;
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297 short sError = pdFALSE;
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298 const char * const pcTaskStartMsg = "Priority manipulation tasks started.\r\n";
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299 const char * const pcTaskFailMsg = "Priority manipulation Task Failed\r\n";
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301 /* Just to stop warning messages. */
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302 ( void ) pvParameters;
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304 /* Queue a message for printing to say the task has started. */
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305 vPrintDisplayMessage( &pcTaskStartMsg );
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309 /* Start with the counter at zero. */
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310 ulCounter = ( unsigned long ) 0;
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312 /* First section : */
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314 /* Check the continuous count task is running. */
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315 for( sLoops = 0; sLoops < priLOOPS; sLoops++ )
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317 /* Suspend the continuous count task so we can take a mirror of the
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318 shared variable without risk of corruption. */
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319 vTaskSuspend( xContinuousIncrementHandle );
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320 ulLastCounter = ulCounter;
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321 vTaskResume( xContinuousIncrementHandle );
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323 /* Now delay to ensure the other task has processor time. */
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324 vTaskDelay( priSLEEP_TIME );
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326 /* Check the shared variable again. This time to ensure mutual
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327 exclusion the whole scheduler will be locked. This is just for
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331 if( ulLastCounter == ulCounter )
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333 /* The shared variable has not changed. There is a problem
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334 with the continuous count task so flag an error. */
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337 vPrintDisplayMessage( &pcTaskFailMsg );
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345 /* Second section: */
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347 /* Suspend the continuous counter task so it stops accessing the shared variable. */
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348 vTaskSuspend( xContinuousIncrementHandle );
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350 /* Reset the variable. */
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351 ulCounter = ( unsigned long ) 0;
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353 /* Resume the limited count task which has a higher priority than us.
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354 We should therefore not return from this call until the limited count
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355 task has suspended itself with a known value in the counter variable.
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356 The scheduler suspension is not necessary but is included for test
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359 vTaskResume( xLimitedIncrementHandle );
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362 /* Does the counter variable have the expected value? */
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363 if( ulCounter != priMAX_COUNT )
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366 vPrintDisplayMessage( &pcTaskFailMsg );
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369 if( sError == pdFALSE )
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371 /* If no errors have occurred then increment the check variable. */
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372 portENTER_CRITICAL();
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374 portEXIT_CRITICAL();
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377 #if configUSE_PREEMPTION == 0
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381 /* Resume the continuous count task and do it all again. */
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382 vTaskResume( xContinuousIncrementHandle );
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385 /*-----------------------------------------------------------*/
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387 static void vQueueSendWhenSuspendedTask( void *pvParameters )
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389 static unsigned long ulValueToSend = ( unsigned long ) 0;
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390 const char * const pcTaskStartMsg = "Queue send while suspended task started.\r\n";
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391 const char * const pcTaskFailMsg = "Queue send while suspended failed.\r\n";
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393 /* Just to stop warning messages. */
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394 ( void ) pvParameters;
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396 /* Queue a message for printing to say the task has started. */
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397 vPrintDisplayMessage( &pcTaskStartMsg );
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403 /* We must not block while the scheduler is suspended! */
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404 if( xQueueSend( xSuspendedTestQueue, ( void * ) &ulValueToSend, priNO_BLOCK ) != pdTRUE )
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406 if( xSuspendedQueueSendError == pdFALSE )
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409 vPrintDisplayMessage( &pcTaskFailMsg );
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413 xSuspendedQueueSendError = pdTRUE;
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418 vTaskDelay( priSLEEP_TIME );
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423 /*-----------------------------------------------------------*/
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425 static void vQueueReceiveWhenSuspendedTask( void *pvParameters )
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427 static unsigned long ulExpectedValue = ( unsigned long ) 0, ulReceivedValue;
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428 const char * const pcTaskStartMsg = "Queue receive while suspended task started.\r\n";
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429 const char * const pcTaskFailMsg = "Queue receive while suspended failed.\r\n";
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430 portBASE_TYPE xGotValue;
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432 /* Just to stop warning messages. */
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433 ( void ) pvParameters;
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435 /* Queue a message for printing to say the task has started. */
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436 vPrintDisplayMessage( &pcTaskStartMsg );
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442 /* Suspending the scheduler here is fairly pointless and
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443 undesirable for a normal application. It is done here purely
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444 to test the scheduler. The inner xTaskResumeAll() should
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445 never return pdTRUE as the scheduler is still locked by the
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451 xGotValue = xQueueReceive( xSuspendedTestQueue, ( void * ) &ulReceivedValue, priNO_BLOCK );
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453 if( xTaskResumeAll() )
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455 xSuspendedQueueReceiveError = pdTRUE;
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460 #if configUSE_PREEMPTION == 0
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464 } while( xGotValue == pdFALSE );
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466 if( ulReceivedValue != ulExpectedValue )
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468 if( xSuspendedQueueReceiveError == pdFALSE )
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470 vPrintDisplayMessage( &pcTaskFailMsg );
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472 xSuspendedQueueReceiveError = pdTRUE;
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478 /*-----------------------------------------------------------*/
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480 static void prvChangePriorityWhenSuspendedTask( void *pvParameters )
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482 const char * const pcTaskStartMsg = "Priority change when suspended task started.\r\n";
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483 const char * const pcTaskFailMsg = "Priority change when suspended task failed.\r\n";
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485 /* Just to stop warning messages. */
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486 ( void ) pvParameters;
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488 /* Queue a message for printing to say the task has started. */
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489 vPrintDisplayMessage( &pcTaskStartMsg );
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493 /* Start with the counter at 0 so we know what the counter should be
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494 when we check it next. */
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495 ulPrioritySetCounter = ( unsigned long ) 0;
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497 /* Resume the helper task. At this time it has a priority lower than
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498 ours so no context switch should occur. */
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499 vTaskResume( xChangePriorityWhenSuspendedHandle );
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501 /* Check to ensure the task just resumed has not executed. */
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502 portENTER_CRITICAL();
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504 if( ulPrioritySetCounter != ( unsigned long ) 0 )
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506 xPriorityRaiseWhenSuspendedError = pdTRUE;
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507 vPrintDisplayMessage( &pcTaskFailMsg );
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510 portEXIT_CRITICAL();
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512 /* Now try raising the priority while the scheduler is suspended. */
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515 vTaskPrioritySet( xChangePriorityWhenSuspendedHandle, ( configMAX_PRIORITIES - 1 ) );
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517 /* Again, even though the helper task has a priority greater than
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518 ours, it should not have executed yet because the scheduler is
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520 portENTER_CRITICAL();
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522 if( ulPrioritySetCounter != ( unsigned long ) 0 )
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524 xPriorityRaiseWhenSuspendedError = pdTRUE;
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525 vPrintDisplayMessage( &pcTaskFailMsg );
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528 portEXIT_CRITICAL();
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532 /* Now the scheduler has been resumed the helper task should
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533 immediately preempt us and execute. When it executes it will increment
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534 the ulPrioritySetCounter exactly once before suspending itself.
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536 We should now always find the counter set to 1. */
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537 portENTER_CRITICAL();
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539 if( ulPrioritySetCounter != ( unsigned long ) 1 )
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541 xPriorityRaiseWhenSuspendedError = pdTRUE;
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542 vPrintDisplayMessage( &pcTaskFailMsg );
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545 portEXIT_CRITICAL();
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547 /* Delay until we try this again. */
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548 vTaskDelay( priSLEEP_TIME * 2 );
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550 /* Set the priority of the helper task back ready for the next
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551 execution of this task. */
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553 vTaskPrioritySet( xChangePriorityWhenSuspendedHandle, tskIDLE_PRIORITY );
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557 /*-----------------------------------------------------------*/
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559 static void prvChangePriorityHelperTask( void *pvParameters )
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561 /* Just to stop warning messages. */
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562 ( void ) pvParameters;
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566 /* This is the helper task for prvChangePriorityWhenSuspendedTask().
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567 It has it's priority raised and lowered. When it runs it simply
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568 increments the counter then suspends itself again. This allows
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569 prvChangePriorityWhenSuspendedTask() to know how many times it has
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571 ulPrioritySetCounter++;
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572 vTaskSuspend( NULL );
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575 /*-----------------------------------------------------------*/
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577 /* Called to check that all the created tasks are still running without error. */
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578 portBASE_TYPE xAreDynamicPriorityTasksStillRunning( void )
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580 /* Keep a history of the check variables so we know if it has been incremented
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581 since the last call. */
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582 static unsigned short usLastTaskCheck = ( unsigned short ) 0;
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583 portBASE_TYPE xReturn = pdTRUE;
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585 /* Check the tasks are still running by ensuring the check variable
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586 is still incrementing. */
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588 if( usCheckVariable == usLastTaskCheck )
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590 /* The check has not incremented so an error exists. */
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594 if( xSuspendedQueueSendError == pdTRUE )
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599 if( xSuspendedQueueReceiveError == pdTRUE )
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604 if( xPriorityRaiseWhenSuspendedError == pdTRUE )
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609 usLastTaskCheck = usCheckVariable;
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