2 FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.
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4 This file is part of the FreeRTOS distribution.
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6 FreeRTOS is free software; you can redistribute it and/or modify it under
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7 the terms of the GNU General Public License (version 2) as published by the
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8 Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS without being obliged to provide the
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11 source code for proprietary components outside of the FreeRTOS kernel.
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12 Alternative commercial license and support terms are also available upon
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13 request. See the licensing section of http://www.FreeRTOS.org for full
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16 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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18 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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21 You should have received a copy of the GNU General Public License along
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22 with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
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23 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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26 ***************************************************************************
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28 * The FreeRTOS eBook and reference manual are available to purchase for a *
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29 * small fee. Help yourself get started quickly while also helping the *
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30 * FreeRTOS project! See http://www.FreeRTOS.org/Documentation for details *
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32 ***************************************************************************
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36 Please ensure to read the configuration and relevant port sections of the
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37 online documentation.
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39 http://www.FreeRTOS.org - Documentation, latest information, license and
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42 http://www.SafeRTOS.com - A version that is certified for use in safety
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45 http://www.OpenRTOS.com - Commercial support, development, porting,
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46 licensing and training services.
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49 /* Scheduler includes. */
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50 #include "FreeRTOS.h"
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54 /* Demo includes. */
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58 * The LCD is written to by more than one task so is controlled by this
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59 * 'gatekeeper' task. This is the only task that is actually permitted to
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60 * access the LCD directly. Other tasks wanting to display a message send
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61 * the message to the gatekeeper.
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63 static void vLCDTask( void *pvParameters );
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66 * Setup the peripherals required to communicate with the LCD.
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68 static void prvSetupLCD( void );
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71 * Move to the first (0) or second (1) row of the LCD.
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73 static void prvLCDGotoRow( unsigned portSHORT usRow );
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76 * Write a string of text to the LCD.
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78 static void prvLCDPutString( portCHAR *pcString );
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83 static void prvLCDClear( void );
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85 /*-----------------------------------------------------------*/
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87 /* Brief delay to permit the LCD to catch up with commands. */
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88 #define lcdVERY_SHORT_DELAY ( 1 )
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89 #define lcdSHORT_DELAY ( 4 / portTICK_RATE_MS )
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90 #define lcdLONG_DELAY ( 15 / portTICK_RATE_MS )
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93 #define lcdCLEAR ( 0x01 )
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94 #define lcdHOME ( 0x02 )
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95 #define lcdLINE2 ( 0xc0 )
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97 /* SFR that seems to be missing from the standard header files. */
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98 #define PMAEN *( ( unsigned short * ) 0x60c )
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100 /* LCD R/W signal. */
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101 #define lcdRW LATDbits.LATD5
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103 /* LCD lcdRS signal. */
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104 #define lcdRS LATBbits.LATB15
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106 /* LCD lcdE signal . */
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107 #define lcdE LATDbits.LATD4
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109 /* Control signal pin direction. */
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110 #define RW_TRIS TRISDbits.TRISD5
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111 #define RS_TRIS TRISBbits.TRISB15
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112 #define E_TRIS TRISDbits.TRISD4
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114 /* Port for LCD data */
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115 #define lcdDATA LATE
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116 #define lcdDATAPORT PORTE
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118 /* I/O setup for data Port. */
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119 #define TRISDATA TRISE
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121 /* The length of the queue used to send messages to the LCD gatekeeper task. */
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122 #define lcdQUEUE_SIZE 3
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123 /*-----------------------------------------------------------*/
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125 /* The queue used to send messages to the LCD task. */
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126 xQueueHandle xLCDQueue;
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128 static void prvLCDCommand( portCHAR cCommand );
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129 static void prvLCDData( portCHAR cChar );
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131 /*-----------------------------------------------------------*/
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133 xQueueHandle xStartLCDTask( void )
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135 /* Create the queue used by the LCD task. Messages for display on the LCD
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136 are received via this queue. */
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137 xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
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139 /* Start the task that will write to the LCD. The LCD hardware is
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140 initialised from within the task itself so delays can be used. */
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141 xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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145 /*-----------------------------------------------------------*/
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147 static void prvLCDGotoRow( unsigned portSHORT usRow )
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151 prvLCDCommand( lcdHOME );
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155 prvLCDCommand( lcdLINE2 );
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158 /*-----------------------------------------------------------*/
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160 static void prvLCDCommand( portCHAR cCommand )
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162 /* Prepare RD0 - RD7. */
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163 lcdDATA &= 0xFF00;
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165 /* Command byte to lcd. */
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166 lcdDATA |= cCommand;
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168 /* Ensure lcdRW is 0. */
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172 /* Toggle lcdE line. */
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174 vTaskDelay( lcdVERY_SHORT_DELAY );
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177 vTaskDelay( lcdSHORT_DELAY );
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179 /*-----------------------------------------------------------*/
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181 static void prvLCDData( portCHAR cChar )
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183 /* ensure lcdRW is 0. */
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186 /* Assert register select to 1. */
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189 /* Prepare RD0 - RD7. */
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190 lcdDATA &= 0xFF00;
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192 /* Data byte to lcd. */
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199 /* Toggle lcdE signal. */
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202 /* Negate register select to 0. */
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205 vTaskDelay( lcdVERY_SHORT_DELAY );
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207 /*-----------------------------------------------------------*/
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209 static void prvLCDPutString( portCHAR *pcString )
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211 /* Write out each character with appropriate delay between each. */
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214 prvLCDData( *pcString );
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216 vTaskDelay( lcdSHORT_DELAY );
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219 /*-----------------------------------------------------------*/
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221 static void prvLCDClear( void )
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223 prvLCDCommand( lcdCLEAR );
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225 /*-----------------------------------------------------------*/
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227 static void prvSetupLCD( void )
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229 /* Wait for proper power up. */
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230 vTaskDelay( lcdLONG_DELAY );
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232 /* Set initial states for the data and control pins */
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235 /* R/W state set low. */
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238 /* lcdRS state set low. */
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241 /* lcdE state set low. */
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244 /* Set data and control pins to outputs */
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247 /* lcdRW pin set as output. */
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250 /* lcdRS pin set as output. */
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253 /* lcdE pin set as output. */
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256 /* 1st LCD initialization sequence */
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264 /* Toggle lcdE signal. */
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267 vTaskDelay( lcdSHORT_DELAY );
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268 vTaskDelay( lcdSHORT_DELAY );
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269 vTaskDelay( lcdSHORT_DELAY );
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271 /* 2nd LCD initialization sequence */
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279 /* Toggle lcdE signal. */
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282 vTaskDelay( lcdSHORT_DELAY );
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284 /* 3rd LCD initialization sequence */
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292 /* Toggle lcdE signal. */
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295 vTaskDelay( lcdSHORT_DELAY );
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298 /* Function set. */
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299 prvLCDCommand( 0x38 );
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301 /* Display on/off control, cursor blink off (0x0C). */
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302 prvLCDCommand( 0x0C );
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304 /* Entry mode set (0x06). */
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305 prvLCDCommand( 0x06 );
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307 prvLCDCommand( lcdCLEAR );
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309 /*-----------------------------------------------------------*/
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311 static void vLCDTask( void *pvParameters )
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313 xLCDMessage xMessage;
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314 unsigned portSHORT usRow = 0;
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316 /* Initialise the hardware. This uses delays so must not be called prior
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317 to the scheduler being started. */
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320 /* Welcome message. */
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321 prvLCDPutString( "www.FreeRTOS.org" );
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325 /* Wait for a message to arrive that requires displaying. */
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326 while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
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328 /* Clear the current display value. */
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331 /* Switch rows each time so we can see that the display is still being
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333 prvLCDGotoRow( usRow & 0x01 );
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335 prvLCDPutString( xMessage.pcMessage );
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337 /* Delay the requested amount of time to ensure the text just written
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338 to the LCD is not overwritten. */
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339 vTaskDelay( xMessage.xMinDisplayTime );
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