2 FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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5 http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS tutorial books are available in pdf and paperback. *
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10 * Complete, revised, and edited pdf reference manuals are also *
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13 * Purchasing FreeRTOS documentation will not only help you, by *
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14 * ensuring you get running as quickly as possible and with an *
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15 * in-depth knowledge of how to use FreeRTOS, it will also help *
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16 * the FreeRTOS project to continue with its mission of providing *
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17 * professional grade, cross platform, de facto standard solutions *
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18 * for microcontrollers - completely free of charge! *
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20 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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22 * Thank you for using FreeRTOS, and thank you for your support! *
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24 ***************************************************************************
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27 This file is part of the FreeRTOS distribution.
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29 FreeRTOS is free software; you can redistribute it and/or modify it under
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30 the terms of the GNU General Public License (version 2) as published by the
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31 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not it can be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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75 /* Scheduler includes. */
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76 #include "FreeRTOS.h"
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80 /* Demo includes. */
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84 * The LCD is written to by more than one task so is controlled by this
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85 * 'gatekeeper' task. This is the only task that is actually permitted to
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86 * access the LCD directly. Other tasks wanting to display a message send
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87 * the message to the gatekeeper.
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89 static void vLCDTask( void *pvParameters );
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92 * Setup the peripherals required to communicate with the LCD.
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94 static void prvSetupLCD( void );
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97 * Move to the first (0) or second (1) row of the LCD.
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99 static void prvLCDGotoRow( unsigned portSHORT usRow );
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102 * Write a string of text to the LCD.
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104 static void prvLCDPutString( portCHAR *pcString );
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109 static void prvLCDClear( void );
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111 /*-----------------------------------------------------------*/
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113 /* Brief delay to permit the LCD to catch up with commands. */
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114 #define lcdVERY_SHORT_DELAY ( 1 )
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115 #define lcdSHORT_DELAY ( 4 / portTICK_RATE_MS )
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116 #define lcdLONG_DELAY ( 15 / portTICK_RATE_MS )
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118 /* LCD commands. */
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119 #define lcdCLEAR ( 0x01 )
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120 #define lcdHOME ( 0x02 )
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121 #define lcdLINE2 ( 0xc0 )
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123 /* SFR that seems to be missing from the standard header files. */
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124 #define PMAEN *( ( unsigned short * ) 0x60c )
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126 /* LCD R/W signal. */
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127 #define lcdRW LATDbits.LATD5
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129 /* LCD lcdRS signal. */
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130 #define lcdRS LATBbits.LATB15
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132 /* LCD lcdE signal . */
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133 #define lcdE LATDbits.LATD4
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135 /* Control signal pin direction. */
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136 #define RW_TRIS TRISDbits.TRISD5
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137 #define RS_TRIS TRISBbits.TRISB15
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138 #define E_TRIS TRISDbits.TRISD4
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140 /* Port for LCD data */
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141 #define lcdDATA LATE
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142 #define lcdDATAPORT PORTE
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144 /* I/O setup for data Port. */
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145 #define TRISDATA TRISE
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147 /* The length of the queue used to send messages to the LCD gatekeeper task. */
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148 #define lcdQUEUE_SIZE 3
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149 /*-----------------------------------------------------------*/
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151 /* The queue used to send messages to the LCD task. */
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152 xQueueHandle xLCDQueue;
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154 static void prvLCDCommand( portCHAR cCommand );
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155 static void prvLCDData( portCHAR cChar );
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157 /*-----------------------------------------------------------*/
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159 xQueueHandle xStartLCDTask( void )
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161 /* Create the queue used by the LCD task. Messages for display on the LCD
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162 are received via this queue. */
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163 xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
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165 /* Start the task that will write to the LCD. The LCD hardware is
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166 initialised from within the task itself so delays can be used. */
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167 xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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171 /*-----------------------------------------------------------*/
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173 static void prvLCDGotoRow( unsigned portSHORT usRow )
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177 prvLCDCommand( lcdHOME );
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181 prvLCDCommand( lcdLINE2 );
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184 /*-----------------------------------------------------------*/
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186 static void prvLCDCommand( portCHAR cCommand )
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188 /* Prepare RD0 - RD7. */
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189 lcdDATA &= 0xFF00;
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191 /* Command byte to lcd. */
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192 lcdDATA |= cCommand;
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194 /* Ensure lcdRW is 0. */
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198 /* Toggle lcdE line. */
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200 vTaskDelay( lcdVERY_SHORT_DELAY );
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203 vTaskDelay( lcdSHORT_DELAY );
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205 /*-----------------------------------------------------------*/
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207 static void prvLCDData( portCHAR cChar )
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209 /* ensure lcdRW is 0. */
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212 /* Assert register select to 1. */
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215 /* Prepare RD0 - RD7. */
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216 lcdDATA &= 0xFF00;
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218 /* Data byte to lcd. */
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225 /* Toggle lcdE signal. */
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228 /* Negate register select to 0. */
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231 vTaskDelay( lcdVERY_SHORT_DELAY );
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233 /*-----------------------------------------------------------*/
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235 static void prvLCDPutString( portCHAR *pcString )
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237 /* Write out each character with appropriate delay between each. */
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240 prvLCDData( *pcString );
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242 vTaskDelay( lcdSHORT_DELAY );
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245 /*-----------------------------------------------------------*/
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247 static void prvLCDClear( void )
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249 prvLCDCommand( lcdCLEAR );
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251 /*-----------------------------------------------------------*/
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253 static void prvSetupLCD( void )
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255 /* Wait for proper power up. */
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256 vTaskDelay( lcdLONG_DELAY );
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258 /* Set initial states for the data and control pins */
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261 /* R/W state set low. */
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264 /* lcdRS state set low. */
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267 /* lcdE state set low. */
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270 /* Set data and control pins to outputs */
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273 /* lcdRW pin set as output. */
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276 /* lcdRS pin set as output. */
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279 /* lcdE pin set as output. */
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282 /* 1st LCD initialization sequence */
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290 /* Toggle lcdE signal. */
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293 vTaskDelay( lcdSHORT_DELAY );
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294 vTaskDelay( lcdSHORT_DELAY );
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295 vTaskDelay( lcdSHORT_DELAY );
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297 /* 2nd LCD initialization sequence */
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305 /* Toggle lcdE signal. */
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308 vTaskDelay( lcdSHORT_DELAY );
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310 /* 3rd LCD initialization sequence */
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318 /* Toggle lcdE signal. */
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321 vTaskDelay( lcdSHORT_DELAY );
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324 /* Function set. */
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325 prvLCDCommand( 0x38 );
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327 /* Display on/off control, cursor blink off (0x0C). */
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328 prvLCDCommand( 0x0C );
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330 /* Entry mode set (0x06). */
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331 prvLCDCommand( 0x06 );
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333 prvLCDCommand( lcdCLEAR );
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335 /*-----------------------------------------------------------*/
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337 static void vLCDTask( void *pvParameters )
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339 xLCDMessage xMessage;
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340 unsigned portSHORT usRow = 0;
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342 /* Initialise the hardware. This uses delays so must not be called prior
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343 to the scheduler being started. */
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346 /* Welcome message. */
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347 prvLCDPutString( "www.FreeRTOS.org" );
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351 /* Wait for a message to arrive that requires displaying. */
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352 while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
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354 /* Clear the current display value. */
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357 /* Switch rows each time so we can see that the display is still being
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359 prvLCDGotoRow( usRow & 0x01 );
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361 prvLCDPutString( xMessage.pcMessage );
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363 /* Delay the requested amount of time to ensure the text just written
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364 to the LCD is not overwritten. */
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365 vTaskDelay( xMessage.xMinDisplayTime );
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