2 FreeRTOS V7.0.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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5 ***************************************************************************
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7 * FreeRTOS tutorial books are available in pdf and paperback. *
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8 * Complete, revised, and edited pdf reference manuals are also *
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11 * Purchasing FreeRTOS documentation will not only help you, by *
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12 * ensuring you get running as quickly as possible and with an *
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13 * in-depth knowledge of how to use FreeRTOS, it will also help *
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14 * the FreeRTOS project to continue with its mission of providing *
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15 * professional grade, cross platform, de facto standard solutions *
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16 * for microcontrollers - completely free of charge! *
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18 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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20 * Thank you for using FreeRTOS, and thank you for your support! *
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22 ***************************************************************************
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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 modification to the GPL is included to allow you to
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31 distribute a combined work that includes FreeRTOS without being obliged to
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32 provide the source code for proprietary components outside of the FreeRTOS
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33 kernel. FreeRTOS is distributed in the hope that it will be useful, but
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34 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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35 or 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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54 /* Scheduler includes. */
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55 #include "FreeRTOS.h"
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59 /* Demo includes. */
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63 * The LCD is written to by more than one task so is controlled by this
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64 * 'gatekeeper' task. This is the only task that is actually permitted to
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65 * access the LCD directly. Other tasks wanting to display a message send
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66 * the message to the gatekeeper.
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68 static void vLCDTask( void *pvParameters );
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71 * Setup the peripherals required to communicate with the LCD.
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73 static void prvSetupLCD( void );
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76 * Move to the first (0) or second (1) row of the LCD.
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78 static void prvLCDGotoRow( unsigned portSHORT usRow );
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81 * Write a string of text to the LCD.
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83 static void prvLCDPutString( portCHAR *pcString );
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88 static void prvLCDClear( void );
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90 /*-----------------------------------------------------------*/
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92 /* Brief delay to permit the LCD to catch up with commands. */
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93 #define lcdVERY_SHORT_DELAY ( 1 )
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94 #define lcdSHORT_DELAY ( 4 / portTICK_RATE_MS )
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95 #define lcdLONG_DELAY ( 15 / portTICK_RATE_MS )
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98 #define lcdCLEAR ( 0x01 )
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99 #define lcdHOME ( 0x02 )
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100 #define lcdLINE2 ( 0xc0 )
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102 /* SFR that seems to be missing from the standard header files. */
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103 #define PMAEN *( ( unsigned short * ) 0x60c )
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105 /* LCD R/W signal. */
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106 #define lcdRW LATDbits.LATD5
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108 /* LCD lcdRS signal. */
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109 #define lcdRS LATBbits.LATB15
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111 /* LCD lcdE signal . */
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112 #define lcdE LATDbits.LATD4
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114 /* Control signal pin direction. */
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115 #define RW_TRIS TRISDbits.TRISD5
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116 #define RS_TRIS TRISBbits.TRISB15
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117 #define E_TRIS TRISDbits.TRISD4
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119 /* Port for LCD data */
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120 #define lcdDATA LATE
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121 #define lcdDATAPORT PORTE
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123 /* I/O setup for data Port. */
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124 #define TRISDATA TRISE
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126 /* The length of the queue used to send messages to the LCD gatekeeper task. */
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127 #define lcdQUEUE_SIZE 3
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128 /*-----------------------------------------------------------*/
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130 /* The queue used to send messages to the LCD task. */
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131 xQueueHandle xLCDQueue;
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133 static void prvLCDCommand( portCHAR cCommand );
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134 static void prvLCDData( portCHAR cChar );
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136 /*-----------------------------------------------------------*/
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138 xQueueHandle xStartLCDTask( void )
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140 /* Create the queue used by the LCD task. Messages for display on the LCD
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141 are received via this queue. */
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142 xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
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144 /* Start the task that will write to the LCD. The LCD hardware is
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145 initialised from within the task itself so delays can be used. */
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146 xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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150 /*-----------------------------------------------------------*/
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152 static void prvLCDGotoRow( unsigned portSHORT usRow )
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156 prvLCDCommand( lcdHOME );
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160 prvLCDCommand( lcdLINE2 );
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163 /*-----------------------------------------------------------*/
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165 static void prvLCDCommand( portCHAR cCommand )
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167 /* Prepare RD0 - RD7. */
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168 lcdDATA &= 0xFF00;
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170 /* Command byte to lcd. */
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171 lcdDATA |= cCommand;
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173 /* Ensure lcdRW is 0. */
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177 /* Toggle lcdE line. */
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179 vTaskDelay( lcdVERY_SHORT_DELAY );
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182 vTaskDelay( lcdSHORT_DELAY );
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184 /*-----------------------------------------------------------*/
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186 static void prvLCDData( portCHAR cChar )
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188 /* ensure lcdRW is 0. */
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191 /* Assert register select to 1. */
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194 /* Prepare RD0 - RD7. */
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195 lcdDATA &= 0xFF00;
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197 /* Data byte to lcd. */
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204 /* Toggle lcdE signal. */
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207 /* Negate register select to 0. */
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210 vTaskDelay( lcdVERY_SHORT_DELAY );
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212 /*-----------------------------------------------------------*/
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214 static void prvLCDPutString( portCHAR *pcString )
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216 /* Write out each character with appropriate delay between each. */
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219 prvLCDData( *pcString );
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221 vTaskDelay( lcdSHORT_DELAY );
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224 /*-----------------------------------------------------------*/
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226 static void prvLCDClear( void )
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228 prvLCDCommand( lcdCLEAR );
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230 /*-----------------------------------------------------------*/
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232 static void prvSetupLCD( void )
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234 /* Wait for proper power up. */
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235 vTaskDelay( lcdLONG_DELAY );
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237 /* Set initial states for the data and control pins */
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240 /* R/W state set low. */
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243 /* lcdRS state set low. */
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246 /* lcdE state set low. */
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249 /* Set data and control pins to outputs */
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252 /* lcdRW pin set as output. */
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255 /* lcdRS pin set as output. */
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258 /* lcdE pin set as output. */
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261 /* 1st LCD initialization sequence */
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269 /* Toggle lcdE signal. */
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272 vTaskDelay( lcdSHORT_DELAY );
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273 vTaskDelay( lcdSHORT_DELAY );
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274 vTaskDelay( lcdSHORT_DELAY );
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276 /* 2nd LCD initialization sequence */
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284 /* Toggle lcdE signal. */
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287 vTaskDelay( lcdSHORT_DELAY );
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289 /* 3rd LCD initialization sequence */
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297 /* Toggle lcdE signal. */
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300 vTaskDelay( lcdSHORT_DELAY );
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303 /* Function set. */
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304 prvLCDCommand( 0x38 );
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306 /* Display on/off control, cursor blink off (0x0C). */
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307 prvLCDCommand( 0x0C );
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309 /* Entry mode set (0x06). */
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310 prvLCDCommand( 0x06 );
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312 prvLCDCommand( lcdCLEAR );
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314 /*-----------------------------------------------------------*/
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316 static void vLCDTask( void *pvParameters )
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318 xLCDMessage xMessage;
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319 unsigned portSHORT usRow = 0;
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321 /* Initialise the hardware. This uses delays so must not be called prior
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322 to the scheduler being started. */
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325 /* Welcome message. */
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326 prvLCDPutString( "www.FreeRTOS.org" );
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330 /* Wait for a message to arrive that requires displaying. */
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331 while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
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333 /* Clear the current display value. */
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336 /* Switch rows each time so we can see that the display is still being
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338 prvLCDGotoRow( usRow & 0x01 );
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340 prvLCDPutString( xMessage.pcMessage );
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342 /* Delay the requested amount of time to ensure the text just written
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343 to the LCD is not overwritten. */
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344 vTaskDelay( xMessage.xMinDisplayTime );
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