2 FreeRTOS V7.5.0 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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6 ***************************************************************************
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8 * FreeRTOS provides completely free yet professionally developed, *
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9 * robust, strictly quality controlled, supported, and cross *
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10 * platform software that has become a de facto standard. *
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12 * Help yourself get started quickly and support the FreeRTOS *
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13 * project by purchasing a FreeRTOS tutorial book, reference *
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14 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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18 ***************************************************************************
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20 This file is part of the FreeRTOS distribution.
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22 FreeRTOS is free software; you can redistribute it and/or modify it under
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23 the terms of the GNU General Public License (version 2) as published by the
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24 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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26 >>! NOTE: The modification to the GPL is included to allow you to distribute
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27 >>! a combined work that includes FreeRTOS without being obliged to provide
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28 >>! the source code for proprietary components outside of the FreeRTOS
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31 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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32 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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33 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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34 link: http://www.freertos.org/a00114.html
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38 ***************************************************************************
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40 * Having a problem? Start by reading the FAQ "My application does *
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41 * not run, what could be wrong?" *
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43 * http://www.FreeRTOS.org/FAQHelp.html *
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45 ***************************************************************************
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47 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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48 license and Real Time Engineers Ltd. contact details.
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50 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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51 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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52 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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54 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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55 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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56 licenses offer ticketed support, indemnification and middleware.
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58 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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59 engineered and independently SIL3 certified version for use in safety and
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60 mission critical applications that require provable dependability.
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65 /* Scheduler includes. */
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66 #include "FreeRTOS.h"
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70 /* Demo includes. */
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74 * The LCD is written to by more than one task so is controlled by this
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75 * 'gatekeeper' task. This is the only task that is actually permitted to
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76 * access the LCD directly. Other tasks wanting to display a message send
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77 * the message to the gatekeeper.
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79 static void vLCDTask( void *pvParameters );
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82 * Setup the peripherals required to communicate with the LCD.
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84 static void prvSetupLCD( void );
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87 * Move to the first (0) or second (1) row of the LCD.
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89 static void prvLCDGotoRow( unsigned portSHORT usRow );
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92 * Write a string of text to the LCD.
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94 static void prvLCDPutString( portCHAR *pcString );
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99 static void prvLCDClear( void );
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101 /*-----------------------------------------------------------*/
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103 /* Brief delay to permit the LCD to catch up with commands. */
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104 #define lcdVERY_SHORT_DELAY ( 1 )
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105 #define lcdSHORT_DELAY ( 4 / portTICK_RATE_MS )
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106 #define lcdLONG_DELAY ( 15 / portTICK_RATE_MS )
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108 /* LCD commands. */
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109 #define lcdCLEAR ( 0x01 )
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110 #define lcdHOME ( 0x02 )
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111 #define lcdLINE2 ( 0xc0 )
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113 /* SFR that seems to be missing from the standard header files. */
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114 #define PMAEN *( ( unsigned short * ) 0x60c )
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116 /* LCD R/W signal. */
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117 #define lcdRW LATDbits.LATD5
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119 /* LCD lcdRS signal. */
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120 #define lcdRS LATBbits.LATB15
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122 /* LCD lcdE signal . */
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123 #define lcdE LATDbits.LATD4
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125 /* Control signal pin direction. */
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126 #define RW_TRIS TRISDbits.TRISD5
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127 #define RS_TRIS TRISBbits.TRISB15
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128 #define E_TRIS TRISDbits.TRISD4
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130 /* Port for LCD data */
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131 #define lcdDATA LATE
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132 #define lcdDATAPORT PORTE
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134 /* I/O setup for data Port. */
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135 #define TRISDATA TRISE
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137 /* The length of the queue used to send messages to the LCD gatekeeper task. */
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138 #define lcdQUEUE_SIZE 3
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139 /*-----------------------------------------------------------*/
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141 /* The queue used to send messages to the LCD task. */
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142 xQueueHandle xLCDQueue;
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144 static void prvLCDCommand( portCHAR cCommand );
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145 static void prvLCDData( portCHAR cChar );
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147 /*-----------------------------------------------------------*/
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149 xQueueHandle xStartLCDTask( void )
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151 /* Create the queue used by the LCD task. Messages for display on the LCD
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152 are received via this queue. */
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153 xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
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155 /* Start the task that will write to the LCD. The LCD hardware is
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156 initialised from within the task itself so delays can be used. */
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157 xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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161 /*-----------------------------------------------------------*/
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163 static void prvLCDGotoRow( unsigned portSHORT usRow )
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167 prvLCDCommand( lcdHOME );
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171 prvLCDCommand( lcdLINE2 );
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174 /*-----------------------------------------------------------*/
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176 static void prvLCDCommand( portCHAR cCommand )
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178 /* Prepare RD0 - RD7. */
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179 lcdDATA &= 0xFF00;
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181 /* Command byte to lcd. */
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182 lcdDATA |= cCommand;
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184 /* Ensure lcdRW is 0. */
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188 /* Toggle lcdE line. */
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190 vTaskDelay( lcdVERY_SHORT_DELAY );
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193 vTaskDelay( lcdSHORT_DELAY );
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195 /*-----------------------------------------------------------*/
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197 static void prvLCDData( portCHAR cChar )
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199 /* ensure lcdRW is 0. */
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202 /* Assert register select to 1. */
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205 /* Prepare RD0 - RD7. */
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206 lcdDATA &= 0xFF00;
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208 /* Data byte to lcd. */
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215 /* Toggle lcdE signal. */
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218 /* Negate register select to 0. */
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221 vTaskDelay( lcdVERY_SHORT_DELAY );
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223 /*-----------------------------------------------------------*/
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225 static void prvLCDPutString( portCHAR *pcString )
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227 /* Write out each character with appropriate delay between each. */
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230 prvLCDData( *pcString );
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232 vTaskDelay( lcdSHORT_DELAY );
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235 /*-----------------------------------------------------------*/
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237 static void prvLCDClear( void )
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239 prvLCDCommand( lcdCLEAR );
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241 /*-----------------------------------------------------------*/
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243 static void prvSetupLCD( void )
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245 /* Wait for proper power up. */
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246 vTaskDelay( lcdLONG_DELAY );
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248 /* Set initial states for the data and control pins */
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251 /* R/W state set low. */
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254 /* lcdRS state set low. */
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257 /* lcdE state set low. */
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260 /* Set data and control pins to outputs */
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263 /* lcdRW pin set as output. */
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266 /* lcdRS pin set as output. */
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269 /* lcdE pin set as output. */
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272 /* 1st LCD initialization sequence */
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280 /* Toggle lcdE signal. */
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283 vTaskDelay( lcdSHORT_DELAY );
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284 vTaskDelay( lcdSHORT_DELAY );
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285 vTaskDelay( lcdSHORT_DELAY );
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287 /* 2nd LCD initialization sequence */
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295 /* Toggle lcdE signal. */
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298 vTaskDelay( lcdSHORT_DELAY );
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300 /* 3rd LCD initialization sequence */
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308 /* Toggle lcdE signal. */
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311 vTaskDelay( lcdSHORT_DELAY );
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314 /* Function set. */
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315 prvLCDCommand( 0x38 );
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317 /* Display on/off control, cursor blink off (0x0C). */
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318 prvLCDCommand( 0x0C );
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320 /* Entry mode set (0x06). */
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321 prvLCDCommand( 0x06 );
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323 prvLCDCommand( lcdCLEAR );
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325 /*-----------------------------------------------------------*/
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327 static void vLCDTask( void *pvParameters )
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329 xLCDMessage xMessage;
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330 unsigned portSHORT usRow = 0;
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332 /* Initialise the hardware. This uses delays so must not be called prior
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333 to the scheduler being started. */
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336 /* Welcome message. */
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337 prvLCDPutString( "www.FreeRTOS.org" );
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341 /* Wait for a message to arrive that requires displaying. */
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342 while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
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344 /* Clear the current display value. */
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347 /* Switch rows each time so we can see that the display is still being
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349 prvLCDGotoRow( usRow & 0x01 );
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351 prvLCDPutString( xMessage.pcMessage );
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353 /* Delay the requested amount of time to ensure the text just written
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354 to the LCD is not overwritten. */
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355 vTaskDelay( xMessage.xMinDisplayTime );
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