2 FreeRTOS.org V4.7.2 - 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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28 Please ensure to read the configuration and relevant port sections of the
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29 online documentation.
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31 +++ http://www.FreeRTOS.org +++
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32 Documentation, latest information, license and contact details.
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34 +++ http://www.SafeRTOS.com +++
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35 A version that is certified for use in safety critical systems.
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37 +++ http://www.OpenRTOS.com +++
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38 Commercial support, development, porting, licensing and training services.
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40 ***************************************************************************
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43 /* Scheduler includes. */
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44 #include "FreeRTOS.h"
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48 /* Demo includes. */
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52 * The LCD is written to by more than one task so is controlled by this
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53 * 'gatekeeper' task. This is the only task that is actually permitted to
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54 * access the LCD directly. Other tasks wanting to display a message send
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55 * the message to the gatekeeper.
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57 static void vLCDTask( void *pvParameters );
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60 * Setup the peripherals required to communicate with the LCD.
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62 static void prvSetupLCD( void );
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65 * Move to the first (0) or second (1) row of the LCD.
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67 static void prvLCDGotoRow( unsigned portSHORT usRow );
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70 * Write a string of text to the LCD.
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72 static void prvLCDPutString( portCHAR *pcString );
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77 static void prvLCDClear( void );
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79 /*-----------------------------------------------------------*/
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81 /* Brief delay to permit the LCD to catch up with commands. */
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82 #define lcdVERY_SHORT_DELAY ( 1 )
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83 #define lcdSHORT_DELAY ( 4 / portTICK_RATE_MS )
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84 #define lcdLONG_DELAY ( 15 / portTICK_RATE_MS )
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87 #define lcdCLEAR ( 0x01 )
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88 #define lcdHOME ( 0x02 )
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89 #define lcdLINE2 ( 0xc0 )
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91 /* SFR that seems to be missing from the standard header files. */
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92 #define PMAEN *( ( unsigned short * ) 0x60c )
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94 /* LCD R/W signal. */
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95 #define lcdRW LATDbits.LATD5
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97 /* LCD lcdRS signal. */
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98 #define lcdRS LATBbits.LATB15
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100 /* LCD lcdE signal . */
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101 #define lcdE LATDbits.LATD4
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103 /* Control signal pin direction. */
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104 #define RW_TRIS TRISDbits.TRISD5
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105 #define RS_TRIS TRISBbits.TRISB15
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106 #define E_TRIS TRISDbits.TRISD4
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108 /* Port for LCD data */
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109 #define lcdDATA LATE
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110 #define lcdDATAPORT PORTE
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112 /* I/O setup for data Port. */
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113 #define TRISDATA TRISE
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115 /* The length of the queue used to send messages to the LCD gatekeeper task. */
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116 #define lcdQUEUE_SIZE 3
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117 /*-----------------------------------------------------------*/
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119 /* The queue used to send messages to the LCD task. */
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120 xQueueHandle xLCDQueue;
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122 static void prvLCDCommand( portCHAR cCommand );
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123 static void prvLCDData( portCHAR cChar );
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125 /*-----------------------------------------------------------*/
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127 xQueueHandle xStartLCDTask( void )
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129 /* Create the queue used by the LCD task. Messages for display on the LCD
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130 are received via this queue. */
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131 xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
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133 /* Start the task that will write to the LCD. The LCD hardware is
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134 initialised from within the task itself so delays can be used. */
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135 xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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139 /*-----------------------------------------------------------*/
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141 static void prvLCDGotoRow( unsigned portSHORT usRow )
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145 prvLCDCommand( lcdHOME );
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149 prvLCDCommand( lcdLINE2 );
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152 /*-----------------------------------------------------------*/
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154 static void prvLCDCommand( portCHAR cCommand )
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156 /* Prepare RD0 - RD7. */
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157 lcdDATA &= 0xFF00;
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159 /* Command byte to lcd. */
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160 lcdDATA |= cCommand;
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162 /* Ensure lcdRW is 0. */
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166 /* Toggle lcdE line. */
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168 vTaskDelay( lcdVERY_SHORT_DELAY );
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171 vTaskDelay( lcdSHORT_DELAY );
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173 /*-----------------------------------------------------------*/
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175 static void prvLCDData( portCHAR cChar )
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177 /* ensure lcdRW is 0. */
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180 /* Assert register select to 1. */
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183 /* Prepare RD0 - RD7. */
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184 lcdDATA &= 0xFF00;
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186 /* Data byte to lcd. */
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193 /* Toggle lcdE signal. */
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196 /* Negate register select to 0. */
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199 vTaskDelay( lcdVERY_SHORT_DELAY );
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201 /*-----------------------------------------------------------*/
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203 static void prvLCDPutString( portCHAR *pcString )
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205 /* Write out each character with appropriate delay between each. */
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208 prvLCDData( *pcString );
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210 vTaskDelay( lcdSHORT_DELAY );
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213 /*-----------------------------------------------------------*/
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215 static void prvLCDClear( void )
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217 prvLCDCommand( lcdCLEAR );
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219 /*-----------------------------------------------------------*/
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221 static void prvSetupLCD( void )
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223 /* Wait for proper power up. */
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224 vTaskDelay( lcdLONG_DELAY );
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226 /* Set initial states for the data and control pins */
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229 /* R/W state set low. */
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232 /* lcdRS state set low. */
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235 /* lcdE state set low. */
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238 /* Set data and control pins to outputs */
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241 /* lcdRW pin set as output. */
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244 /* lcdRS pin set as output. */
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247 /* lcdE pin set as output. */
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250 /* 1st LCD initialization sequence */
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258 /* Toggle lcdE signal. */
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261 vTaskDelay( lcdSHORT_DELAY );
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262 vTaskDelay( lcdSHORT_DELAY );
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263 vTaskDelay( lcdSHORT_DELAY );
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265 /* 2nd LCD initialization sequence */
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273 /* Toggle lcdE signal. */
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276 vTaskDelay( lcdSHORT_DELAY );
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278 /* 3rd LCD initialization sequence */
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286 /* Toggle lcdE signal. */
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289 vTaskDelay( lcdSHORT_DELAY );
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292 /* Function set. */
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293 prvLCDCommand( 0x38 );
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295 /* Display on/off control, cursor blink off (0x0C). */
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296 prvLCDCommand( 0x0C );
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298 /* Entry mode set (0x06). */
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299 prvLCDCommand( 0x06 );
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301 prvLCDCommand( lcdCLEAR );
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303 /*-----------------------------------------------------------*/
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305 static void vLCDTask( void *pvParameters )
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307 xLCDMessage xMessage;
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308 unsigned portSHORT usRow = 0;
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310 /* Initialise the hardware. This uses delays so must not be called prior
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311 to the scheduler being started. */
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314 /* Welcome message. */
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315 prvLCDPutString( "www.FreeRTOS.org" );
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319 /* Wait for a message to arrive that requires displaying. */
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320 while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
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322 /* Clear the current display value. */
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325 /* Switch rows each time so we can see that the display is still being
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327 prvLCDGotoRow( usRow & 0x01 );
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329 prvLCDPutString( xMessage.pcMessage );
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331 /* Delay the requested amount of time to ensure the text just written
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332 to the LCD is not overwritten. */
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333 vTaskDelay( xMessage.xMinDisplayTime );
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