2 FreeRTOS.org V5.0.4 - Copyright (C) 2003-2008 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
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2 of the License, or
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9 (at your option) any later version.
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11 FreeRTOS.org is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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16 You should have received a copy of the GNU General Public License
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17 along with FreeRTOS.org; if not, write to the Free Software
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 A special exception to the GPL can be applied should you wish to distribute
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21 a combined work that includes FreeRTOS.org, without being obliged to provide
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22 the source code for any proprietary components. See the licensing section
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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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27 ***************************************************************************
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29 * SAVE TIME AND MONEY! We can port FreeRTOS.org to your own hardware, *
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30 * and even write all or part of your application on your behalf. *
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31 * See http://www.OpenRTOS.com for details of the services we provide to *
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32 * expedite your project. *
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34 ***************************************************************************
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35 ***************************************************************************
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37 Please ensure to read the configuration and relevant port sections of the
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38 online documentation.
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40 http://www.FreeRTOS.org - Documentation, latest information, license and
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43 http://www.SafeRTOS.com - A version that is certified for use in safety
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46 http://www.OpenRTOS.com - Commercial support, development, porting,
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47 licensing and training services.
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50 /* Scheduler includes. */
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51 #include "FreeRTOS.h"
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55 /* Demo includes. */
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59 * The LCD is written to by more than one task so is controlled by this
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60 * 'gatekeeper' task. This is the only task that is actually permitted to
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61 * access the LCD directly. Other tasks wanting to display a message send
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62 * the message to the gatekeeper.
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64 static void vLCDTask( void *pvParameters );
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67 * Setup the peripherals required to communicate with the LCD.
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69 static void prvSetupLCD( void );
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72 * Move to the first (0) or second (1) row of the LCD.
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74 static void prvLCDGotoRow( unsigned portSHORT usRow );
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77 * Write a string of text to the LCD.
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79 static void prvLCDPutString( portCHAR *pcString );
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84 static void prvLCDClear( void );
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86 /*-----------------------------------------------------------*/
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88 /* Brief delay to permit the LCD to catch up with commands. */
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89 #define lcdVERY_SHORT_DELAY ( 1 )
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90 #define lcdSHORT_DELAY ( 4 / portTICK_RATE_MS )
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91 #define lcdLONG_DELAY ( 15 / portTICK_RATE_MS )
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94 #define lcdCLEAR ( 0x01 )
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95 #define lcdHOME ( 0x02 )
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96 #define lcdLINE2 ( 0xc0 )
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98 /* SFR that seems to be missing from the standard header files. */
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99 #define PMAEN *( ( unsigned short * ) 0x60c )
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101 /* LCD R/W signal. */
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102 #define lcdRW LATDbits.LATD5
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104 /* LCD lcdRS signal. */
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105 #define lcdRS LATBbits.LATB15
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107 /* LCD lcdE signal . */
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108 #define lcdE LATDbits.LATD4
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110 /* Control signal pin direction. */
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111 #define RW_TRIS TRISDbits.TRISD5
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112 #define RS_TRIS TRISBbits.TRISB15
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113 #define E_TRIS TRISDbits.TRISD4
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115 /* Port for LCD data */
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116 #define lcdDATA LATE
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117 #define lcdDATAPORT PORTE
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119 /* I/O setup for data Port. */
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120 #define TRISDATA TRISE
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122 /* The length of the queue used to send messages to the LCD gatekeeper task. */
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123 #define lcdQUEUE_SIZE 3
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124 /*-----------------------------------------------------------*/
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126 /* The queue used to send messages to the LCD task. */
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127 xQueueHandle xLCDQueue;
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129 static void prvLCDCommand( portCHAR cCommand );
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130 static void prvLCDData( portCHAR cChar );
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132 /*-----------------------------------------------------------*/
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134 xQueueHandle xStartLCDTask( void )
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136 /* Create the queue used by the LCD task. Messages for display on the LCD
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137 are received via this queue. */
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138 xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
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140 /* Start the task that will write to the LCD. The LCD hardware is
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141 initialised from within the task itself so delays can be used. */
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142 xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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146 /*-----------------------------------------------------------*/
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148 static void prvLCDGotoRow( unsigned portSHORT usRow )
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152 prvLCDCommand( lcdHOME );
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156 prvLCDCommand( lcdLINE2 );
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159 /*-----------------------------------------------------------*/
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161 static void prvLCDCommand( portCHAR cCommand )
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163 /* Prepare RD0 - RD7. */
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164 lcdDATA &= 0xFF00;
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166 /* Command byte to lcd. */
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167 lcdDATA |= cCommand;
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169 /* Ensure lcdRW is 0. */
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173 /* Toggle lcdE line. */
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175 vTaskDelay( lcdVERY_SHORT_DELAY );
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178 vTaskDelay( lcdSHORT_DELAY );
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180 /*-----------------------------------------------------------*/
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182 static void prvLCDData( portCHAR cChar )
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184 /* ensure lcdRW is 0. */
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187 /* Assert register select to 1. */
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190 /* Prepare RD0 - RD7. */
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191 lcdDATA &= 0xFF00;
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193 /* Data byte to lcd. */
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200 /* Toggle lcdE signal. */
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203 /* Negate register select to 0. */
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206 vTaskDelay( lcdVERY_SHORT_DELAY );
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208 /*-----------------------------------------------------------*/
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210 static void prvLCDPutString( portCHAR *pcString )
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212 /* Write out each character with appropriate delay between each. */
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215 prvLCDData( *pcString );
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217 vTaskDelay( lcdSHORT_DELAY );
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220 /*-----------------------------------------------------------*/
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222 static void prvLCDClear( void )
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224 prvLCDCommand( lcdCLEAR );
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226 /*-----------------------------------------------------------*/
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228 static void prvSetupLCD( void )
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230 /* Wait for proper power up. */
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231 vTaskDelay( lcdLONG_DELAY );
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233 /* Set initial states for the data and control pins */
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236 /* R/W state set low. */
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239 /* lcdRS state set low. */
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242 /* lcdE state set low. */
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245 /* Set data and control pins to outputs */
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248 /* lcdRW pin set as output. */
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251 /* lcdRS pin set as output. */
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254 /* lcdE pin set as output. */
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257 /* 1st LCD initialization sequence */
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265 /* Toggle lcdE signal. */
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268 vTaskDelay( lcdSHORT_DELAY );
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269 vTaskDelay( lcdSHORT_DELAY );
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270 vTaskDelay( lcdSHORT_DELAY );
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272 /* 2nd LCD initialization sequence */
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280 /* Toggle lcdE signal. */
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283 vTaskDelay( lcdSHORT_DELAY );
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285 /* 3rd LCD initialization sequence */
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293 /* Toggle lcdE signal. */
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296 vTaskDelay( lcdSHORT_DELAY );
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299 /* Function set. */
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300 prvLCDCommand( 0x38 );
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302 /* Display on/off control, cursor blink off (0x0C). */
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303 prvLCDCommand( 0x0C );
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305 /* Entry mode set (0x06). */
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306 prvLCDCommand( 0x06 );
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308 prvLCDCommand( lcdCLEAR );
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310 /*-----------------------------------------------------------*/
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312 static void vLCDTask( void *pvParameters )
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314 xLCDMessage xMessage;
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315 unsigned portSHORT usRow = 0;
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317 /* Initialise the hardware. This uses delays so must not be called prior
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318 to the scheduler being started. */
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321 /* Welcome message. */
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322 prvLCDPutString( "www.FreeRTOS.org" );
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326 /* Wait for a message to arrive that requires displaying. */
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327 while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
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329 /* Clear the current display value. */
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332 /* Switch rows each time so we can see that the display is still being
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334 prvLCDGotoRow( usRow & 0x01 );
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336 prvLCDPutString( xMessage.pcMessage );
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338 /* Delay the requested amount of time to ensure the text just written
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339 to the LCD is not overwritten. */
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340 vTaskDelay( xMessage.xMinDisplayTime );
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