2 FreeRTOS.org V5.4.0 - Copyright (C) 2003-2009 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License (version 2) as published
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8 by the Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS.org without being obliged to provide
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11 the source code for any proprietary components. Alternative commercial
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12 license and support terms are also available upon request. See the
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13 licensing section of http://www.FreeRTOS.org for full details.
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15 FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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20 You should have received a copy of the GNU General Public License along
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21 with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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22 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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25 ***************************************************************************
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27 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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29 * This is a concise, step by step, 'hands on' guide that describes both *
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30 * general multitasking concepts and FreeRTOS specifics. It presents and *
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31 * explains numerous examples that are written using the FreeRTOS API. *
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32 * Full source code for all the examples is provided in an accompanying *
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35 ***************************************************************************
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39 Please ensure to read the configuration and relevant port sections of the
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40 online documentation.
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42 http://www.FreeRTOS.org - Documentation, latest information, license and
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45 http://www.SafeRTOS.com - A version that is certified for use in safety
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48 http://www.OpenRTOS.com - Commercial support, development, porting,
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49 licensing and training services.
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54 * This project contains an application demonstrating the use of the
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55 * FreeRTOS.org mini real time scheduler on the Luminary Micro LM3S811 Eval
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56 * board. See http://www.FreeRTOS.org for more information.
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58 * main() simply sets up the hardware, creates all the demo application tasks,
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59 * then starts the scheduler. http://www.freertos.org/a00102.html provides
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60 * more information on the standard demo tasks.
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62 * In addition to a subset of the standard demo application tasks, main.c also
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63 * defines the following tasks:
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65 * + A 'Print' task. The print task is the only task permitted to access the
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66 * LCD - thus ensuring mutual exclusion and consistent access to the resource.
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67 * Other tasks do not access the LCD directly, but instead send the text they
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68 * wish to display to the print task. The print task spends most of its time
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69 * blocked - only waking when a message is queued for display.
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71 * + A 'Button handler' task. The eval board contains a user push button that
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72 * is configured to generate interrupts. The interrupt handler uses a
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73 * semaphore to wake the button handler task - demonstrating how the priority
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74 * mechanism can be used to defer interrupt processing to the task level. The
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75 * button handler task sends a message both to the LCD (via the print task) and
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76 * the UART where it can be viewed using a dumb terminal (via the UART to USB
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77 * converter on the eval board). NOTES: The dumb terminal must be closed in
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78 * order to reflash the microcontroller. A very basic interrupt driven UART
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79 * driver is used that does not use the FIFO. 19200 baud is used.
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81 * + A 'check' task. The check task only executes every five seconds but has a
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82 * high priority so is guaranteed to get processor time. Its function is to
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83 * check that all the other tasks are still operational and that no errors have
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84 * been detected at any time. If no errors have every been detected 'PASS' is
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85 * written to the display (via the print task) - if an error has ever been
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86 * detected the message is changed to 'FAIL'. The position of the message is
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87 * changed for each write.
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92 /* Environment includes. */
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93 #include "DriverLib.h"
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95 /* Scheduler includes. */
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96 #include "FreeRTOS.h"
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101 /* Demo app includes. */
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102 #include "integer.h"
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104 #include "semtest.h"
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105 #include "BlockQ.h"
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107 /* Delay between cycles of the 'check' task. */
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108 #define mainCHECK_DELAY ( ( portTickType ) 5000 / portTICK_RATE_MS )
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110 /* UART configuration - note this does not use the FIFO so is not very
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112 #define mainBAUD_RATE ( 19200 )
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113 #define mainFIFO_SET ( 0x10 )
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115 /* Demo task priorities. */
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116 #define mainQUEUE_POLL_PRIORITY ( tskIDLE_PRIORITY + 2 )
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117 #define mainCHECK_TASK_PRIORITY ( tskIDLE_PRIORITY + 3 )
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118 #define mainSEM_TEST_PRIORITY ( tskIDLE_PRIORITY + 1 )
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119 #define mainBLOCK_Q_PRIORITY ( tskIDLE_PRIORITY + 2 )
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121 /* Demo board specifics. */
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122 #define mainPUSH_BUTTON GPIO_PIN_4
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125 #define mainQUEUE_SIZE ( 3 )
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126 #define mainDEBOUNCE_DELAY ( ( portTickType ) 150 / portTICK_RATE_MS )
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127 #define mainNO_DELAY ( ( portTickType ) 0 )
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129 * Configure the processor and peripherals for this demo.
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131 static void prvSetupHardware( void );
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134 * The 'check' task, as described at the top of this file.
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136 static void vCheckTask( void *pvParameters );
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139 * The task that is woken by the ISR that processes GPIO interrupts originating
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140 * from the push button.
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142 static void vButtonHandlerTask( void *pvParameters );
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145 * The task that controls access to the LCD.
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147 static void vPrintTask( void *pvParameter );
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149 /* String that is transmitted on the UART. */
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150 static portCHAR *cMessage = "Task woken by button interrupt! --- ";
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151 static volatile portCHAR *pcNextChar;
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153 /* The semaphore used to wake the button handler task from within the GPIO
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154 interrupt handler. */
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155 xSemaphoreHandle xButtonSemaphore;
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157 /* The queue used to send strings to the print task for display on the LCD. */
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158 xQueueHandle xPrintQueue;
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160 /*-----------------------------------------------------------*/
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164 /* Configure the clocks, UART and GPIO. */
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165 prvSetupHardware();
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167 /* Create the semaphore used to wake the button handler task from the GPIO
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169 vSemaphoreCreateBinary( xButtonSemaphore );
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170 xSemaphoreTake( xButtonSemaphore, 0 );
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172 /* Create the queue used to pass message to vPrintTask. */
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173 xPrintQueue = xQueueCreate( mainQUEUE_SIZE, sizeof( portCHAR * ) );
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175 /* Start the standard demo tasks. */
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176 vStartIntegerMathTasks( tskIDLE_PRIORITY );
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177 vStartPolledQueueTasks( mainQUEUE_POLL_PRIORITY );
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178 vStartSemaphoreTasks( mainSEM_TEST_PRIORITY );
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179 vStartBlockingQueueTasks( mainBLOCK_Q_PRIORITY );
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181 /* Start the tasks defined within the file. */
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182 xTaskCreate( vCheckTask, "Check", configMINIMAL_STACK_SIZE, NULL, mainCHECK_TASK_PRIORITY, NULL );
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183 xTaskCreate( vButtonHandlerTask, "Status", configMINIMAL_STACK_SIZE, NULL, mainCHECK_TASK_PRIORITY + 1, NULL );
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184 xTaskCreate( vPrintTask, "Print", configMINIMAL_STACK_SIZE, NULL, mainCHECK_TASK_PRIORITY - 1, NULL );
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186 /* Start the scheduler. */
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187 vTaskStartScheduler();
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189 /* Will only get here if there was insufficient heap to start the
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194 /*-----------------------------------------------------------*/
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196 static void vCheckTask( void *pvParameters )
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198 portBASE_TYPE xErrorOccurred = pdFALSE;
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199 portTickType xLastExecutionTime;
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200 const portCHAR *pcPassMessage = "PASS";
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201 const portCHAR *pcFailMessage = "FAIL";
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203 /* Initialise xLastExecutionTime so the first call to vTaskDelayUntil()
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204 works correctly. */
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205 xLastExecutionTime = xTaskGetTickCount();
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209 /* Perform this check every mainCHECK_DELAY milliseconds. */
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210 vTaskDelayUntil( &xLastExecutionTime, mainCHECK_DELAY );
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212 /* Has an error been found in any task? */
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214 if( xAreIntegerMathsTaskStillRunning() != pdTRUE )
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216 xErrorOccurred = pdTRUE;
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219 if( xArePollingQueuesStillRunning() != pdTRUE )
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221 xErrorOccurred = pdTRUE;
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224 if( xAreSemaphoreTasksStillRunning() != pdTRUE )
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226 xErrorOccurred = pdTRUE;
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229 if( xAreBlockingQueuesStillRunning() != pdTRUE )
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231 xErrorOccurred = pdTRUE;
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234 /* Send either a pass or fail message. If an error is found it is
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235 never cleared again. We do not write directly to the LCD, but instead
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236 queue a message for display by the print task. */
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237 if( xErrorOccurred == pdTRUE )
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239 xQueueSend( xPrintQueue, &pcFailMessage, portMAX_DELAY );
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243 xQueueSend( xPrintQueue, &pcPassMessage, portMAX_DELAY );
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247 /*-----------------------------------------------------------*/
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249 static void prvSetupHardware( void )
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251 /* Setup the PLL. */
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252 SysCtlClockSet( SYSCTL_SYSDIV_10 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN | SYSCTL_XTAL_6MHZ );
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254 /* Setup the push button. */
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255 SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOC);
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256 GPIODirModeSet(GPIO_PORTC_BASE, mainPUSH_BUTTON, GPIO_DIR_MODE_IN);
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257 GPIOIntTypeSet( GPIO_PORTC_BASE, mainPUSH_BUTTON,GPIO_FALLING_EDGE );
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258 IntPrioritySet( INT_GPIOC, configKERNEL_INTERRUPT_PRIORITY );
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259 GPIOPinIntEnable( GPIO_PORTC_BASE, mainPUSH_BUTTON );
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260 IntEnable( INT_GPIOC );
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264 /* Enable the UART. */
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265 SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
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266 SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
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268 /* Set GPIO A0 and A1 as peripheral function. They are used to output the
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270 GPIODirModeSet( GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1, GPIO_DIR_MODE_HW );
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272 /* Configure the UART for 8-N-1 operation. */
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273 UARTConfigSet( UART0_BASE, mainBAUD_RATE, UART_CONFIG_WLEN_8 | UART_CONFIG_PAR_NONE | UART_CONFIG_STOP_ONE );
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275 /* We don't want to use the fifo. This is for test purposes to generate
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276 as many interrupts as possible. */
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277 HWREG( UART0_BASE + UART_O_LCR_H ) &= ~mainFIFO_SET;
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279 /* Enable Tx interrupts. */
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280 HWREG( UART0_BASE + UART_O_IM ) |= UART_INT_TX;
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281 IntPrioritySet( INT_UART0, configKERNEL_INTERRUPT_PRIORITY );
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282 IntEnable( INT_UART0 );
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285 /* Initialise the LCD> */
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286 OSRAMInit( false );
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287 OSRAMStringDraw("www.FreeRTOS.org", 0, 0);
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288 OSRAMStringDraw("LM3S811 demo", 16, 1);
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290 /*-----------------------------------------------------------*/
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292 static void vButtonHandlerTask( void *pvParameters )
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294 const portCHAR *pcInterruptMessage = "Int";
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298 /* Wait for a GPIO interrupt to wake this task. */
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299 while( xSemaphoreTake( xButtonSemaphore, portMAX_DELAY ) != pdPASS );
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301 /* Start the Tx of the message on the UART. */
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302 UARTIntDisable( UART0_BASE, UART_INT_TX );
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304 pcNextChar = cMessage;
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306 /* Send the first character. */
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307 if( !( HWREG( UART0_BASE + UART_O_FR ) & UART_FR_TXFF ) )
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309 HWREG( UART0_BASE + UART_O_DR ) = *pcNextChar;
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314 UARTIntEnable(UART0_BASE, UART_INT_TX);
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316 /* Queue a message for the print task to display on the LCD. */
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317 xQueueSend( xPrintQueue, &pcInterruptMessage, portMAX_DELAY );
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319 /* Make sure we don't process bounces. */
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320 vTaskDelay( mainDEBOUNCE_DELAY );
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321 xSemaphoreTake( xButtonSemaphore, mainNO_DELAY );
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325 /*-----------------------------------------------------------*/
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327 void vUART_ISR(void)
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329 unsigned portLONG ulStatus;
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331 /* What caused the interrupt. */
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332 ulStatus = UARTIntStatus( UART0_BASE, pdTRUE );
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334 /* Clear the interrupt. */
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335 UARTIntClear( UART0_BASE, ulStatus );
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337 /* Was a Tx interrupt pending? */
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338 if( ulStatus & UART_INT_TX )
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340 /* Send the next character in the string. We are not using the FIFO. */
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341 if( *pcNextChar != 0 )
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343 if( !( HWREG( UART0_BASE + UART_O_FR ) & UART_FR_TXFF ) )
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345 HWREG( UART0_BASE + UART_O_DR ) = *pcNextChar;
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351 /*-----------------------------------------------------------*/
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353 void vGPIO_ISR( void )
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355 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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357 /* Clear the interrupt. */
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358 GPIOPinIntClear(GPIO_PORTC_BASE, mainPUSH_BUTTON);
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360 /* Wake the button handler task. */
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361 xSemaphoreGiveFromISR( xButtonSemaphore, &xHigherPriorityTaskWoken );
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363 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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365 /*-----------------------------------------------------------*/
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367 static void vPrintTask( void *pvParameters )
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369 portCHAR *pcMessage;
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370 unsigned portBASE_TYPE uxLine = 0, uxRow = 0;
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374 /* Wait for a message to arrive. */
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375 xQueueReceive( xPrintQueue, &pcMessage, portMAX_DELAY );
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377 /* Write the message to the LCD. */
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381 OSRAMStringDraw( pcMessage, uxLine & 0x3f, uxRow & 0x01);
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