2 FreeRTOS V6.0.0 - Copyright (C) 2009 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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11 * + Wanting to improve your FreeRTOS skills and productivity *
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13 * then take a look at the FreeRTOS eBook *
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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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56 * This project contains an application demonstrating the use of the
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57 * FreeRTOS.org mini real time scheduler on the Luminary Micro LM3S811 Eval
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58 * board. See http://www.FreeRTOS.org for more information.
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60 * main() simply sets up the hardware, creates all the demo application tasks,
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61 * then starts the scheduler. http://www.freertos.org/a00102.html provides
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62 * more information on the standard demo tasks.
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64 * In addition to a subset of the standard demo application tasks, main.c also
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65 * defines the following tasks:
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67 * + A 'Print' task. The print task is the only task permitted to access the
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68 * LCD - thus ensuring mutual exclusion and consistent access to the resource.
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69 * Other tasks do not access the LCD directly, but instead send the text they
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70 * wish to display to the print task. The print task spends most of its time
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71 * blocked - only waking when a message is queued for display.
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73 * + A 'Button handler' task. The eval board contains a user push button that
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74 * is configured to generate interrupts. The interrupt handler uses a
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75 * semaphore to wake the button handler task - demonstrating how the priority
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76 * mechanism can be used to defer interrupt processing to the task level. The
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77 * button handler task sends a message both to the LCD (via the print task) and
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78 * the UART where it can be viewed using a dumb terminal (via the UART to USB
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79 * converter on the eval board). NOTES: The dumb terminal must be closed in
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80 * order to reflash the microcontroller. A very basic interrupt driven UART
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81 * driver is used that does not use the FIFO. 19200 baud is used.
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83 * + A 'check' task. The check task only executes every five seconds but has a
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84 * high priority so is guaranteed to get processor time. Its function is to
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85 * check that all the other tasks are still operational and that no errors have
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86 * been detected at any time. If no errors have every been detected 'PASS' is
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87 * written to the display (via the print task) - if an error has ever been
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88 * detected the message is changed to 'FAIL'. The position of the message is
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89 * changed for each write.
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94 /* Environment includes. */
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95 #include "DriverLib.h"
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97 /* Scheduler includes. */
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98 #include "FreeRTOS.h"
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101 #include "semphr.h"
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103 /* Demo app includes. */
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104 #include "integer.h"
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106 #include "semtest.h"
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107 #include "BlockQ.h"
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109 /* Delay between cycles of the 'check' task. */
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110 #define mainCHECK_DELAY ( ( portTickType ) 5000 / portTICK_RATE_MS )
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112 /* UART configuration - note this does not use the FIFO so is not very
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114 #define mainBAUD_RATE ( 19200 )
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115 #define mainFIFO_SET ( 0x10 )
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117 /* Demo task priorities. */
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118 #define mainQUEUE_POLL_PRIORITY ( tskIDLE_PRIORITY + 2 )
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119 #define mainCHECK_TASK_PRIORITY ( tskIDLE_PRIORITY + 3 )
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120 #define mainSEM_TEST_PRIORITY ( tskIDLE_PRIORITY + 1 )
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121 #define mainBLOCK_Q_PRIORITY ( tskIDLE_PRIORITY + 2 )
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123 /* Demo board specifics. */
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124 #define mainPUSH_BUTTON GPIO_PIN_4
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127 #define mainQUEUE_SIZE ( 3 )
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128 #define mainDEBOUNCE_DELAY ( ( portTickType ) 150 / portTICK_RATE_MS )
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129 #define mainNO_DELAY ( ( portTickType ) 0 )
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131 * Configure the processor and peripherals for this demo.
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133 static void prvSetupHardware( void );
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136 * The 'check' task, as described at the top of this file.
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138 static void vCheckTask( void *pvParameters );
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141 * The task that is woken by the ISR that processes GPIO interrupts originating
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142 * from the push button.
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144 static void vButtonHandlerTask( void *pvParameters );
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147 * The task that controls access to the LCD.
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149 static void vPrintTask( void *pvParameter );
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151 /* String that is transmitted on the UART. */
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152 static portCHAR *cMessage = "Task woken by button interrupt! --- ";
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153 static volatile portCHAR *pcNextChar;
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155 /* The semaphore used to wake the button handler task from within the GPIO
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156 interrupt handler. */
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157 xSemaphoreHandle xButtonSemaphore;
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159 /* The queue used to send strings to the print task for display on the LCD. */
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160 xQueueHandle xPrintQueue;
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162 /*-----------------------------------------------------------*/
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166 /* Configure the clocks, UART and GPIO. */
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167 prvSetupHardware();
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169 /* Create the semaphore used to wake the button handler task from the GPIO
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171 vSemaphoreCreateBinary( xButtonSemaphore );
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172 xSemaphoreTake( xButtonSemaphore, 0 );
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174 /* Create the queue used to pass message to vPrintTask. */
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175 xPrintQueue = xQueueCreate( mainQUEUE_SIZE, sizeof( portCHAR * ) );
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177 /* Start the standard demo tasks. */
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178 vStartIntegerMathTasks( tskIDLE_PRIORITY );
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179 vStartPolledQueueTasks( mainQUEUE_POLL_PRIORITY );
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180 vStartSemaphoreTasks( mainSEM_TEST_PRIORITY );
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181 vStartBlockingQueueTasks( mainBLOCK_Q_PRIORITY );
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183 /* Start the tasks defined within the file. */
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184 xTaskCreate( vCheckTask, "Check", configMINIMAL_STACK_SIZE, NULL, mainCHECK_TASK_PRIORITY, NULL );
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185 xTaskCreate( vButtonHandlerTask, "Status", configMINIMAL_STACK_SIZE, NULL, mainCHECK_TASK_PRIORITY + 1, NULL );
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186 xTaskCreate( vPrintTask, "Print", configMINIMAL_STACK_SIZE, NULL, mainCHECK_TASK_PRIORITY - 1, NULL );
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188 /* Start the scheduler. */
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189 vTaskStartScheduler();
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191 /* Will only get here if there was insufficient heap to start the
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196 /*-----------------------------------------------------------*/
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198 static void vCheckTask( void *pvParameters )
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200 portBASE_TYPE xErrorOccurred = pdFALSE;
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201 portTickType xLastExecutionTime;
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202 const portCHAR *pcPassMessage = "PASS";
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203 const portCHAR *pcFailMessage = "FAIL";
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205 /* Initialise xLastExecutionTime so the first call to vTaskDelayUntil()
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206 works correctly. */
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207 xLastExecutionTime = xTaskGetTickCount();
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211 /* Perform this check every mainCHECK_DELAY milliseconds. */
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212 vTaskDelayUntil( &xLastExecutionTime, mainCHECK_DELAY );
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214 /* Has an error been found in any task? */
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216 if( xAreIntegerMathsTaskStillRunning() != pdTRUE )
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218 xErrorOccurred = pdTRUE;
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221 if( xArePollingQueuesStillRunning() != pdTRUE )
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223 xErrorOccurred = pdTRUE;
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226 if( xAreSemaphoreTasksStillRunning() != pdTRUE )
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228 xErrorOccurred = pdTRUE;
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231 if( xAreBlockingQueuesStillRunning() != pdTRUE )
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233 xErrorOccurred = pdTRUE;
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236 /* Send either a pass or fail message. If an error is found it is
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237 never cleared again. We do not write directly to the LCD, but instead
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238 queue a message for display by the print task. */
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239 if( xErrorOccurred == pdTRUE )
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241 xQueueSend( xPrintQueue, &pcFailMessage, portMAX_DELAY );
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245 xQueueSend( xPrintQueue, &pcPassMessage, portMAX_DELAY );
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249 /*-----------------------------------------------------------*/
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251 static void prvSetupHardware( void )
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253 /* Setup the PLL. */
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254 SysCtlClockSet( SYSCTL_SYSDIV_10 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN | SYSCTL_XTAL_6MHZ );
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256 /* Setup the push button. */
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257 SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOC);
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258 GPIODirModeSet(GPIO_PORTC_BASE, mainPUSH_BUTTON, GPIO_DIR_MODE_IN);
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259 GPIOIntTypeSet( GPIO_PORTC_BASE, mainPUSH_BUTTON,GPIO_FALLING_EDGE );
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260 IntPrioritySet( INT_GPIOC, configKERNEL_INTERRUPT_PRIORITY );
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261 GPIOPinIntEnable( GPIO_PORTC_BASE, mainPUSH_BUTTON );
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262 IntEnable( INT_GPIOC );
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266 /* Enable the UART. */
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267 SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
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268 SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
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270 /* Set GPIO A0 and A1 as peripheral function. They are used to output the
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272 GPIODirModeSet( GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1, GPIO_DIR_MODE_HW );
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274 /* Configure the UART for 8-N-1 operation. */
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275 UARTConfigSet( UART0_BASE, mainBAUD_RATE, UART_CONFIG_WLEN_8 | UART_CONFIG_PAR_NONE | UART_CONFIG_STOP_ONE );
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277 /* We don't want to use the fifo. This is for test purposes to generate
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278 as many interrupts as possible. */
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279 HWREG( UART0_BASE + UART_O_LCR_H ) &= ~mainFIFO_SET;
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281 /* Enable Tx interrupts. */
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282 HWREG( UART0_BASE + UART_O_IM ) |= UART_INT_TX;
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283 IntPrioritySet( INT_UART0, configKERNEL_INTERRUPT_PRIORITY );
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284 IntEnable( INT_UART0 );
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287 /* Initialise the LCD> */
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288 OSRAMInit( false );
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289 OSRAMStringDraw("www.FreeRTOS.org", 0, 0);
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290 OSRAMStringDraw("LM3S811 demo", 16, 1);
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292 /*-----------------------------------------------------------*/
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294 static void vButtonHandlerTask( void *pvParameters )
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296 const portCHAR *pcInterruptMessage = "Int";
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300 /* Wait for a GPIO interrupt to wake this task. */
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301 while( xSemaphoreTake( xButtonSemaphore, portMAX_DELAY ) != pdPASS );
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303 /* Start the Tx of the message on the UART. */
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304 UARTIntDisable( UART0_BASE, UART_INT_TX );
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306 pcNextChar = cMessage;
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308 /* Send the first character. */
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309 if( !( HWREG( UART0_BASE + UART_O_FR ) & UART_FR_TXFF ) )
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311 HWREG( UART0_BASE + UART_O_DR ) = *pcNextChar;
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316 UARTIntEnable(UART0_BASE, UART_INT_TX);
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318 /* Queue a message for the print task to display on the LCD. */
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319 xQueueSend( xPrintQueue, &pcInterruptMessage, portMAX_DELAY );
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321 /* Make sure we don't process bounces. */
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322 vTaskDelay( mainDEBOUNCE_DELAY );
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323 xSemaphoreTake( xButtonSemaphore, mainNO_DELAY );
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327 /*-----------------------------------------------------------*/
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329 void vUART_ISR(void)
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331 unsigned portLONG ulStatus;
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333 /* What caused the interrupt. */
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334 ulStatus = UARTIntStatus( UART0_BASE, pdTRUE );
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336 /* Clear the interrupt. */
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337 UARTIntClear( UART0_BASE, ulStatus );
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339 /* Was a Tx interrupt pending? */
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340 if( ulStatus & UART_INT_TX )
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342 /* Send the next character in the string. We are not using the FIFO. */
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343 if( *pcNextChar != 0 )
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345 if( !( HWREG( UART0_BASE + UART_O_FR ) & UART_FR_TXFF ) )
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347 HWREG( UART0_BASE + UART_O_DR ) = *pcNextChar;
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353 /*-----------------------------------------------------------*/
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355 void vGPIO_ISR( void )
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357 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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359 /* Clear the interrupt. */
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360 GPIOPinIntClear(GPIO_PORTC_BASE, mainPUSH_BUTTON);
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362 /* Wake the button handler task. */
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363 xSemaphoreGiveFromISR( xButtonSemaphore, &xHigherPriorityTaskWoken );
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365 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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367 /*-----------------------------------------------------------*/
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369 static void vPrintTask( void *pvParameters )
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371 portCHAR *pcMessage;
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372 unsigned portBASE_TYPE uxLine = 0, uxRow = 0;
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376 /* Wait for a message to arrive. */
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377 xQueueReceive( xPrintQueue, &pcMessage, portMAX_DELAY );
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379 /* Write the message to the LCD. */
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383 OSRAMStringDraw( pcMessage, uxLine & 0x3f, uxRow & 0x01);
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