2 FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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4 ***************************************************************************
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8 * + New to FreeRTOS, *
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9 * + Wanting to learn FreeRTOS or multitasking in general quickly *
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10 * + Looking for basic training, *
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11 * + Wanting to improve your FreeRTOS skills and productivity *
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13 * then take a look at the FreeRTOS books - available as PDF or paperback *
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15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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16 * http://www.FreeRTOS.org/Documentation *
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18 * A pdf reference manual is also available. Both are usually delivered *
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19 * to your inbox within 20 minutes to two hours when purchased between 8am *
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20 * and 8pm GMT (although please allow up to 24 hours in case of *
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21 * exceptional circumstances). Thank you for your support! *
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23 ***************************************************************************
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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 exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 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 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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55 This simple demo project runs on the STM32 Discovery board, which is
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56 populated with an STM32F100RB Cortex-M3 microcontroller. The discovery board
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57 makes an ideal low cost evaluation platform, but the 8K of RAM provided on the
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58 STM32F100RB does not allow the simple application to demonstrate all of all the
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59 FreeRTOS kernel features. Therefore, this simple demo only actively
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60 demonstrates task, queue, timer and interrupt functionality. In addition, the
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61 demo is configured to include malloc failure, idle and stack overflow hook
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64 The idle hook function:
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65 The idle hook function queries the amount of FreeRTOS heap space that is
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66 remaining (see vApplicationIdleHook() defined in this file). The demo
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67 application is configured use 7K or the available 8K of RAM as the FreeRTOS heap.
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68 Memory is only allocated from this heap during initialisation, and this demo
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69 only actually uses 1.6K bytes of the configured 7K available - leaving 5.4K
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70 bytes of heap space unallocated.
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72 The main() Function:
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73 main() creates one software timer, one queue, and two tasks. It then starts the
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76 The Queue Send Task:
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77 The queue send task is implemented by the prvQueueSendTask() function in this
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78 file. prvQueueSendTask() sits in a loop that causes it to repeatedly block for
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79 200 milliseconds, before sending the value 100 to the queue that was created
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80 within main(). Once the value is sent, the task loops back around to block for
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81 another 200 milliseconds.
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83 The Queue Receive Task:
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84 The queue receive task is implemented by the prvQueueReceiveTask() function
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85 in this file. prvQueueReceiveTask() sits in a loop that causes repeatedly
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86 attempt to read data from the queue that was created within main(). When data
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87 is received, the task checks the value of the data, and if the value equals
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88 the expected 100, toggles the green LED. The 'block time' parameter passed to
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89 the queue receive function specifies that the task should be held in the Blocked
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90 state indefinitely to wait for data to be available on the queue. The queue
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91 receive task will only leave the Blocked state when the queue send task writes
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92 to the queue. As the queue send task writes to the queue every 200
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93 milliseconds, the queue receive task leaves the Blocked state every 200
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94 milliseconds, and therefore toggles the green LED every 200 milliseconds.
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96 The LED Software Timer and the Button Interrupt:
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97 The user button B1 is configured to generate an interrupt each time it is
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98 pressed. The interrupt service routine switches the red LED on, and resets the
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99 LED software timer. The LED timer has a 5000 millisecond (5 second) period, and
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100 uses a callback function that is defined to just turn the red LED off.
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101 Therefore, pressing the user button will turn the red LED on, and the LED will
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102 remain on until a full five seconds pass without the button being pressed.
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105 /* Kernel includes. */
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106 #include "FreeRTOS.h"
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109 #include "timers.h"
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111 /* Microsemi drivers/libraries. */
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112 #include "mss_gpio.h"
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113 #include "mss_watchdog.h"
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116 /* Priorities at which the tasks are created. */
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117 #define mainQUEUE_RECEIVE_TASK_PRIORITY ( tskIDLE_PRIORITY + 2 )
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118 #define mainQUEUE_SEND_TASK_PRIORITY ( tskIDLE_PRIORITY + 1 )
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120 /* The rate at which data is sent to the queue, specified in milliseconds, and
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121 converted to ticks using the portTICK_RATE_MS constant. */
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122 #define mainQUEUE_SEND_FREQUENCY_MS ( 200 / portTICK_RATE_MS )
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124 /* The number of items the queue can hold. This is 1 as the receive task
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125 will remove items as they are added, meaning the send task should always find
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126 the queue empty. */
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127 #define mainQUEUE_LENGTH ( 1 )
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129 #define mainTASK_CONTROLLED_LED 0x01UL
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130 #define mainTIMER_CONTROLLED_LED 0x02UL
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131 /*-----------------------------------------------------------*/
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134 * Setup the NVIC, LED outputs, and button inputs.
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136 static void prvSetupHardware( void );
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139 * The tasks as described in the comments at the top of this file.
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141 static void prvQueueReceiveTask( void *pvParameters );
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142 static void prvQueueSendTask( void *pvParameters );
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145 * The LED timer callback function. This does nothing but switch the red LED
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148 static void vLEDTimerCallback( xTimerHandle xTimer );
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150 /*-----------------------------------------------------------*/
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152 /* The queue used by both tasks. */
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153 static xQueueHandle xQueue = NULL;
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155 /* The LED software timer. This uses vLEDTimerCallback() as its callback
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157 static xTimerHandle xLEDTimer = NULL;
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159 volatile unsigned long ulGPIOState = 0UL;
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161 /*-----------------------------------------------------------*/
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165 /* Configure the NVIC, LED outputs and button inputs. */
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166 prvSetupHardware();
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168 /* Create the queue. */
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169 xQueue = xQueueCreate( mainQUEUE_LENGTH, sizeof( unsigned long ) );
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171 if( xQueue != NULL )
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173 /* Start the two tasks as described in the comments at the top of this
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175 xTaskCreate( prvQueueReceiveTask, ( signed char * ) "Rx", configMINIMAL_STACK_SIZE, NULL, mainQUEUE_RECEIVE_TASK_PRIORITY, NULL );
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176 xTaskCreate( prvQueueSendTask, ( signed char * ) "TX", configMINIMAL_STACK_SIZE, NULL, mainQUEUE_SEND_TASK_PRIORITY, NULL );
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178 /* Create the software timer that is responsible for turning off the LED
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179 if the button is not pushed within 5000ms, as described at the top of
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181 xLEDTimer = xTimerCreate( ( const signed char * ) "LEDTimer", /* A text name, purely to help debugging. */
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182 ( 5000 / portTICK_RATE_MS ), /* The timer period, in this case 5000ms (5s). */
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183 pdFALSE, /* This is a one shot timer, so xAutoReload is set to pdFALSE. */
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184 ( void * ) 0, /* The ID is not used, so can be set to anything. */
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185 vLEDTimerCallback /* The callback function that switches the LED off. */
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188 /* Start the tasks and timer running. */
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189 vTaskStartScheduler();
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192 /* If all is well, the scheduler will now be running, and the following line
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193 will never be reached. If the following line does execute, then there was
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194 insufficient FreeRTOS heap memory available for the idle and/or timer tasks
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195 to be created. See the memory management section on the FreeRTOS web site
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196 for more details. */
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199 /*-----------------------------------------------------------*/
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201 static void vLEDTimerCallback( xTimerHandle xTimer )
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203 /* The timer has expired - so no button pushes have occurred in the last
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204 five seconds - turn the LED off. NOTE - accessing the LED port should use
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205 a critical section because it is accessed from multiple tasks, and the
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206 button interrupt - in this trivial case, for simplicity, the critical
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207 section is omitted. */
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208 ulGPIOState |= mainTIMER_CONTROLLED_LED;
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209 MSS_GPIO_set_outputs( ulGPIOState );
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211 /*-----------------------------------------------------------*/
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213 /* The ISR executed when the user button is pushed. */
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214 void GPIO8_IRQHandler( void )
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216 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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218 /* The button was pushed, so ensure the LED is on before resetting the
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219 LED timer. The LED timer will turn the LED off if the button is not
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220 pushed within 5000ms. */
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221 ulGPIOState &= ~mainTIMER_CONTROLLED_LED;
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222 MSS_GPIO_set_outputs( ulGPIOState );
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224 /* This interrupt safe FreeRTOS function can be called from this interrupt
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225 because the interrupt priority is below the
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226 configMAX_SYSCALL_INTERRUPT_PRIORITY setting in FreeRTOSConfig.h. */
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227 xTimerResetFromISR( xLEDTimer, &xHigherPriorityTaskWoken );
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229 /* Clear the interrupt before leaving. */
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230 MSS_GPIO_clear_irq( MSS_GPIO_8 );
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232 /* If calling xTimerResetFromISR() caused a task (in this case the timer
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233 service/daemon task) to unblock, and the unblocked task has a priority
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234 higher than or equal to the task that was interrupted, then
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235 xHigherPriorityTaskWoken will now be set to pdTRUE, and calling
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236 portEND_SWITCHING_ISR() will ensure the unblocked task runs next. */
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237 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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239 /*-----------------------------------------------------------*/
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241 static void prvQueueSendTask( void *pvParameters )
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243 portTickType xNextWakeTime;
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244 const unsigned long ulValueToSend = 100UL;
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246 /* Initialise xNextWakeTime - this only needs to be done once. */
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247 xNextWakeTime = xTaskGetTickCount();
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251 /* Place this task in the blocked state until it is time to run again.
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252 The block time is specified in ticks, the constant used converts ticks
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253 to ms. While in the Blocked state this task will not consume any CPU
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255 vTaskDelayUntil( &xNextWakeTime, mainQUEUE_SEND_FREQUENCY_MS );
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257 /* Send to the queue - causing the queue receive task to unblock and
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258 toggle an LED. 0 is used as the block time so the sending operation
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259 will not block - it shouldn't need to block as the queue should always
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260 be empty at this point in the code. */
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261 xQueueSend( xQueue, &ulValueToSend, 0 );
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264 /*-----------------------------------------------------------*/
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266 static void prvQueueReceiveTask( void *pvParameters )
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268 unsigned long ulReceivedValue;
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272 /* Wait until something arrives in the queue - this task will block
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273 indefinitely provided INCLUDE_vTaskSuspend is set to 1 in
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274 FreeRTOSConfig.h. */
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275 xQueueReceive( xQueue, &ulReceivedValue, portMAX_DELAY );
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277 /* To get here something must have been received from the queue, but
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278 is it the expected value? If it is, toggle the green LED. */
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279 if( ulReceivedValue == 100UL )
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281 /* NOTE - accessing the LED port should use a critical section
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282 because it is accessed from multiple tasks, and the button interrupt
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283 - in this trivial case, for simplicity, the critical section is
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285 if( ( ulGPIOState & mainTASK_CONTROLLED_LED ) != 0 )
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287 ulGPIOState &= ~mainTASK_CONTROLLED_LED;
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291 ulGPIOState |= mainTASK_CONTROLLED_LED;
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293 MSS_GPIO_set_outputs( ulGPIOState );
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297 /*-----------------------------------------------------------*/
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299 static void prvSetupHardware( void )
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301 /* Disable the Watch Dog Timer */
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304 /* Initialise the GPIO */
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307 /* Set up GPIO for the LEDs. */
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308 MSS_GPIO_config( MSS_GPIO_0 , MSS_GPIO_OUTPUT_MODE );
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309 MSS_GPIO_config( MSS_GPIO_1 , MSS_GPIO_OUTPUT_MODE );
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310 MSS_GPIO_config( MSS_GPIO_2 , MSS_GPIO_OUTPUT_MODE );
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311 MSS_GPIO_config( MSS_GPIO_3 , MSS_GPIO_OUTPUT_MODE );
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312 MSS_GPIO_config( MSS_GPIO_4 , MSS_GPIO_OUTPUT_MODE );
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313 MSS_GPIO_config( MSS_GPIO_5 , MSS_GPIO_OUTPUT_MODE );
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314 MSS_GPIO_config( MSS_GPIO_6 , MSS_GPIO_OUTPUT_MODE );
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315 MSS_GPIO_config( MSS_GPIO_7 , MSS_GPIO_OUTPUT_MODE );
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317 /* All LEDs start off. */
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318 ulGPIOState = 0xffffffffUL;
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319 MSS_GPIO_set_outputs( ulGPIOState );
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321 /* Setup the GPIO and the NVIC for the switch used in this simple demo. */
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322 NVIC_EnableIRQ( GPIO8_IRQn );
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323 MSS_GPIO_config( MSS_GPIO_8, MSS_GPIO_INPUT_MODE | MSS_GPIO_IRQ_EDGE_NEGATIVE );
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324 MSS_GPIO_enable_irq( MSS_GPIO_8 );
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326 /*-----------------------------------------------------------*/
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328 void vApplicationMallocFailedHook( void )
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330 /* Called if a call to pvPortMalloc() fails because there is insufficient
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331 free memory available in the FreeRTOS heap. pvPortMalloc() is called
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332 internally by FreeRTOS API functions that create tasks, queues, software
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333 timers, and semaphores. The size of the FreeRTOS heap is set by the
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334 configTOTAL_HEAP_SIZE configuration constant in FreeRTOSConfig.h. */
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337 /*-----------------------------------------------------------*/
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339 void vApplicationStackOverflowHook( xTaskHandle *pxTask, signed char *pcTaskName )
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341 ( void ) pcTaskName;
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344 /* Run time stack overflow checking is performed if
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345 configconfigCHECK_FOR_STACK_OVERFLOW is defined to 1 or 2. This hook
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346 function is called if a stack overflow is detected. */
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349 /*-----------------------------------------------------------*/
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351 void vApplicationIdleHook( void )
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353 volatile size_t xFreeStackSpace;
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355 /* This function is called on each cycle of the idle task. In this case it
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356 does nothing useful, other than report the amout of FreeRTOS heap that
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357 remains unallocated. */
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358 xFreeStackSpace = xPortGetFreeHeapSize();
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360 if( xFreeStackSpace > 100 )
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362 /* By now, the kernel has allocated everything it is going to, so
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363 if there is a lot of heap remaining unallocated then
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364 the value of configTOTAL_HEAP_SIZE in FreeRTOSConfig.h can be
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365 reduced accordingly. */
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