2 * FreeRTOS Kernel V10.0.0
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3 * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software. If you wish to use our Amazon
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14 * FreeRTOS name, please do so in a fair use way that does not cause confusion.
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16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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18 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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19 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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20 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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23 * http://www.FreeRTOS.org
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24 * http://aws.amazon.com/freertos
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26 * 1 tab == 4 spaces!
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30 This simple demo project runs on the STM32 Discovery board, which is
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31 populated with an STM32F100RB Cortex-M3 microcontroller. The discovery board
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32 makes an ideal low cost evaluation platform, but the 8K of RAM provided on the
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33 STM32F100RB does not allow the simple application to demonstrate all of all the
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34 FreeRTOS kernel features. Therefore, this simple demo only actively
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35 demonstrates task, queue, timer and interrupt functionality. In addition, the
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36 demo is configured to include malloc failure, idle and stack overflow hook
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39 The idle hook function:
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40 The idle hook function queries the amount of FreeRTOS heap space that is
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41 remaining (see vApplicationIdleHook() defined in this file). The demo
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42 application is configured to use 7K of the available 8K of RAM as the FreeRTOS
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43 heap. Memory is only allocated from this heap during initialisation, and this
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44 demo only actually uses 1.6K bytes of the configured 7K available - leaving 5.4K
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45 bytes of heap space unallocated.
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47 The main() Function:
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48 main() creates one software timer, one queue, and two tasks. It then starts the
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51 The Queue Send Task:
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52 The queue send task is implemented by the prvQueueSendTask() function in this
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53 file. prvQueueSendTask() sits in a loop that causes it to repeatedly block for
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54 200 milliseconds, before sending the value 100 to the queue that was created
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55 within main(). Once the value is sent, the task loops back around to block for
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56 another 200 milliseconds.
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58 The Queue Receive Task:
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59 The queue receive task is implemented by the prvQueueReceiveTask() function
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60 in this file. prvQueueReceiveTask() sits in a loop where it repeatedly blocks
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61 on attempts to read data from the queue that was created within main(). When
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62 data is received, the task checks the value of the data, and if the value equals
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63 the expected 100, toggles the green LED. The 'block time' parameter passed to
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64 the queue receive function specifies that the task should be held in the Blocked
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65 state indefinitely to wait for data to be available on the queue. The queue
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66 receive task will only leave the Blocked state when the queue send task writes
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67 to the queue. As the queue send task writes to the queue every 200
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68 milliseconds, the queue receive task leaves the Blocked state every 200
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69 milliseconds, and therefore toggles the green LED every 200 milliseconds.
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71 The LED Software Timer and the Button Interrupt:
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72 The user button B1 is configured to generate an interrupt each time it is
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73 pressed. The interrupt service routine switches the red LED on, and resets the
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74 LED software timer. The LED timer has a 5000 millisecond (5 second) period, and
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75 uses a callback function that is defined to just turn the red LED off.
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76 Therefore, pressing the user button will turn the red LED on, and the LED will
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77 remain on until a full five seconds pass without the button being pressed.
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81 /* Kernel includes. */
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82 #include "FreeRTOS.h"
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87 /* STM32 Library includes. */
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88 #include "stm32f10x.h"
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89 #include "STM32vldiscovery.h"
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91 /* Priorities at which the tasks are created. */
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92 #define mainQUEUE_RECEIVE_TASK_PRIORITY ( tskIDLE_PRIORITY + 2 )
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93 #define mainQUEUE_SEND_TASK_PRIORITY ( tskIDLE_PRIORITY + 1 )
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95 /* The rate at which data is sent to the queue, specified in milliseconds, and
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96 converted to ticks using the portTICK_PERIOD_MS constant. */
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97 #define mainQUEUE_SEND_FREQUENCY_MS ( 200 / portTICK_PERIOD_MS )
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99 /* The number of items the queue can hold. This is 1 as the receive task
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100 will remove items as they are added, meaning the send task should always find
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101 the queue empty. */
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102 #define mainQUEUE_LENGTH ( 1 )
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104 /*-----------------------------------------------------------*/
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107 * Setup the NVIC, LED outputs, and button inputs.
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109 static void prvSetupHardware( void );
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112 * The tasks as described in the comments at the top of this file.
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114 static void prvQueueReceiveTask( void *pvParameters );
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115 static void prvQueueSendTask( void *pvParameters );
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118 * The LED timer callback function. This does nothing but switch the red LED
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121 static void vLEDTimerCallback( TimerHandle_t xTimer );
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123 /*-----------------------------------------------------------*/
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125 /* The queue used by both tasks. */
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126 static QueueHandle_t xQueue = NULL;
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128 /* The LED software timer. This uses vLEDTimerCallback() as its callback
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131 static TimerHandle_t xLEDTimer = NULL;
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133 /*-----------------------------------------------------------*/
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137 /* Configure the NVIC, LED outputs and button inputs. */
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138 prvSetupHardware();
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140 /* Create the queue. */
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141 xQueue = xQueueCreate( mainQUEUE_LENGTH, sizeof( unsigned long ) );
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143 if( xQueue != NULL )
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145 /* Start the two tasks as described in the comments at the top of this
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147 xTaskCreate( prvQueueReceiveTask, "Rx", configMINIMAL_STACK_SIZE, NULL, mainQUEUE_RECEIVE_TASK_PRIORITY, NULL );
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148 xTaskCreate( prvQueueSendTask, "TX", configMINIMAL_STACK_SIZE, NULL, mainQUEUE_SEND_TASK_PRIORITY, NULL );
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150 /* Create the software timer that is responsible for turning off the LED
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151 if the button is not pushed within 5000ms, as described at the top of
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153 xLEDTimer = xTimerCreate( "LEDTimer", /* A text name, purely to help debugging. */
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154 ( 5000 / portTICK_PERIOD_MS ),/* The timer period, in this case 5000ms (5s). */
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155 pdFALSE, /* This is a one shot timer, so xAutoReload is set to pdFALSE. */
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156 ( void * ) 0, /* The ID is not used, so can be set to anything. */
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157 vLEDTimerCallback /* The callback function that switches the LED off. */
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160 /* Start the tasks and timer running. */
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161 vTaskStartScheduler();
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164 /* If all is well, the scheduler will now be running, and the following line
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165 will never be reached. If the following line does execute, then there was
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166 insufficient FreeRTOS heap memory available for the idle and/or timer tasks
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167 to be created. See the memory management section on the FreeRTOS web site
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168 for more details. */
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171 /*-----------------------------------------------------------*/
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173 static void vLEDTimerCallback( TimerHandle_t xTimer )
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175 /* The timer has expired - so no button pushes have occurred in the last
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176 five seconds - turn the LED off. NOTE - accessing the LED port should use
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177 a critical section because it is accessed from multiple tasks, and the
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178 button interrupt - in this trivial case, for simplicity, the critical
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179 section is omitted. */
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180 STM32vldiscovery_LEDOff( LED4 );
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182 /*-----------------------------------------------------------*/
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184 /* The ISR executed when the user button is pushed. */
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185 void EXTI0_IRQHandler( void )
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187 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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189 /* The button was pushed, so ensure the LED is on before resetting the
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190 LED timer. The LED timer will turn the LED off if the button is not
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191 pushed within 5000ms. */
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192 STM32vldiscovery_LEDOn( LED4 );
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194 /* This interrupt safe FreeRTOS function can be called from this interrupt
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195 because the interrupt priority is below the
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196 configMAX_SYSCALL_INTERRUPT_PRIORITY setting in FreeRTOSConfig.h. */
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197 xTimerResetFromISR( xLEDTimer, &xHigherPriorityTaskWoken );
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199 /* Clear the interrupt before leaving. */
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200 EXTI_ClearITPendingBit( EXTI_Line0 );
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202 /* If calling xTimerResetFromISR() caused a task (in this case the timer
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203 service/daemon task) to unblock, and the unblocked task has a priority
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204 higher than or equal to the task that was interrupted, then
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205 xHigherPriorityTaskWoken will now be set to pdTRUE, and calling
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206 portEND_SWITCHING_ISR() will ensure the unblocked task runs next. */
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207 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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209 /*-----------------------------------------------------------*/
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211 static void prvQueueSendTask( void *pvParameters )
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213 TickType_t xNextWakeTime;
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214 const unsigned long ulValueToSend = 100UL;
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216 /* Initialise xNextWakeTime - this only needs to be done once. */
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217 xNextWakeTime = xTaskGetTickCount();
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221 /* Place this task in the blocked state until it is time to run again.
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222 The block time is specified in ticks, the constant used converts ticks
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223 to ms. While in the Blocked state this task will not consume any CPU
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225 vTaskDelayUntil( &xNextWakeTime, mainQUEUE_SEND_FREQUENCY_MS );
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227 /* Send to the queue - causing the queue receive task to unblock and
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228 toggle an LED. 0 is used as the block time so the sending operation
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229 will not block - it shouldn't need to block as the queue should always
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230 be empty at this point in the code. */
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231 xQueueSend( xQueue, &ulValueToSend, 0 );
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234 /*-----------------------------------------------------------*/
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236 static void prvQueueReceiveTask( void *pvParameters )
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238 unsigned long ulReceivedValue;
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242 /* Wait until something arrives in the queue - this task will block
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243 indefinitely provided INCLUDE_vTaskSuspend is set to 1 in
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244 FreeRTOSConfig.h. */
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245 xQueueReceive( xQueue, &ulReceivedValue, portMAX_DELAY );
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247 /* To get here something must have been received from the queue, but
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248 is it the expected value? If it is, toggle the green LED. */
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249 if( ulReceivedValue == 100UL )
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251 /* NOTE - accessing the LED port should use a critical section
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252 because it is accessed from multiple tasks, and the button interrupt
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253 - in this trivial case, for simplicity, the critical section is
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255 STM32vldiscovery_LEDToggle( LED3 );
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259 /*-----------------------------------------------------------*/
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261 static void prvSetupHardware( void )
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263 /* Ensure that all 4 interrupt priority bits are used as the pre-emption
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265 NVIC_PriorityGroupConfig( NVIC_PriorityGroup_4 );
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267 /* Set up the LED outputs and the button inputs. */
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268 STM32vldiscovery_LEDInit( LED3 );
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269 STM32vldiscovery_LEDInit( LED4 );
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270 STM32vldiscovery_PBInit( BUTTON_USER, BUTTON_MODE_EXTI );
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272 /* Start with the LEDs off. */
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273 STM32vldiscovery_LEDOff( LED3 );
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274 STM32vldiscovery_LEDOff( LED4 );
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276 /*-----------------------------------------------------------*/
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278 void vApplicationMallocFailedHook( void )
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280 /* Called if a call to pvPortMalloc() fails because there is insufficient
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281 free memory available in the FreeRTOS heap. pvPortMalloc() is called
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282 internally by FreeRTOS API functions that create tasks, queues, software
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283 timers, and semaphores. The size of the FreeRTOS heap is set by the
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284 configTOTAL_HEAP_SIZE configuration constant in FreeRTOSConfig.h. */
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287 /*-----------------------------------------------------------*/
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289 void vApplicationStackOverflowHook( TaskHandle_t pxTask, char *pcTaskName )
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291 ( void ) pcTaskName;
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294 /* Run time stack overflow checking is performed if
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295 configconfigCHECK_FOR_STACK_OVERFLOW is defined to 1 or 2. This hook
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296 function is called if a stack overflow is detected. */
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299 /*-----------------------------------------------------------*/
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301 void vApplicationIdleHook( void )
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303 volatile size_t xFreeStackSpace;
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305 /* This function is called on each cycle of the idle task. In this case it
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306 does nothing useful, other than report the amout of FreeRTOS heap that
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307 remains unallocated. */
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308 xFreeStackSpace = xPortGetFreeHeapSize();
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310 if( xFreeStackSpace > 100 )
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312 /* By now, the kernel has allocated everything it is going to, so
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313 if there is a lot of heap remaining unallocated then
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314 the value of configTOTAL_HEAP_SIZE in FreeRTOSConfig.h can be
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315 reduced accordingly. */
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