2 FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 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 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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31 * This is a concise, step by step, 'hands on' guide that describes both *
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32 * general multitasking concepts and FreeRTOS specifics. It presents and *
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33 * explains numerous examples that are written using the FreeRTOS API. *
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34 * Full source code for all the examples is provided in an accompanying *
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37 ***************************************************************************
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38 ***************************************************************************
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40 Please ensure to read the configuration and relevant port sections of the
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41 online documentation.
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43 http://www.FreeRTOS.org - Documentation, latest information, license and
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46 http://www.SafeRTOS.com - A version that is certified for use in safety
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49 http://www.OpenRTOS.com - Commercial support, development, porting,
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50 licensing and training services.
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53 /* Scheduler includes. */
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54 #include "FreeRTOS.h"
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58 /* Demo includes. */
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62 * The LCD is written to by more than one task so is controlled by this
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63 * 'gatekeeper' task. This is the only task that is actually permitted to
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64 * access the LCD directly. Other tasks wanting to display a message send
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65 * the message to the gatekeeper.
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67 static void vLCDTask( void *pvParameters );
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70 * Setup the peripherals required to communicate with the LCD.
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72 static void prvSetupLCD( void );
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75 * Move to the first (0) or second (1) row of the LCD.
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77 static void prvLCDGotoRow( unsigned portSHORT usRow );
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80 * Write a string of text to the LCD.
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82 static void prvLCDPutString( portCHAR *pcString );
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87 static void prvLCDClear( void );
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89 /*-----------------------------------------------------------*/
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91 /* Brief delay to permit the LCD to catch up with commands. */
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92 #define lcdSHORT_DELAY 3
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94 /* SFR that seems to be missing from the standard header files. */
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95 #define PMAEN *( ( unsigned short * ) 0x60c )
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98 #define lcdDEFAULT_FUNCTION 0x3c
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99 #define lcdDISPLAY_CONTROL 0x0c
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100 #define lcdCLEAR_DISPLAY 0x01
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101 #define lcdENTRY_MODE 0x06
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103 /* The length of the queue used to send messages to the LCD gatekeeper task. */
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104 #define lcdQUEUE_SIZE 3
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105 /*-----------------------------------------------------------*/
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107 /* The queue used to send messages to the LCD task. */
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108 xQueueHandle xLCDQueue;
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111 /*-----------------------------------------------------------*/
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113 xQueueHandle xStartLCDTask( void )
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115 /* Create the queue used by the LCD task. Messages for display on the LCD
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116 are received via this queue. */
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117 xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
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119 /* Start the task that will write to the LCD. The LCD hardware is
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120 initialised from within the task itself so delays can be used. */
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121 xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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125 /*-----------------------------------------------------------*/
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127 static void prvLCDGotoRow( unsigned portSHORT usRow )
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140 vTaskDelay( lcdSHORT_DELAY );
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142 /*-----------------------------------------------------------*/
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144 static void prvLCDPutString( portCHAR *pcString )
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146 /* Write out each character with appropriate delay between each. */
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150 PMDIN1 = *pcString;
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152 vTaskDelay( lcdSHORT_DELAY );
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155 /*-----------------------------------------------------------*/
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157 static void prvLCDClear( void )
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159 /* Clear the display. */
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161 PMDIN1 = lcdCLEAR_DISPLAY;
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162 vTaskDelay( lcdSHORT_DELAY );
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164 /*-----------------------------------------------------------*/
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166 static void prvSetupLCD( void )
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168 /* Setup the PMP. */
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173 vTaskDelay( lcdSHORT_DELAY );
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175 /* Set the default function. */
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176 PMDIN1 = lcdDEFAULT_FUNCTION;
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177 vTaskDelay( lcdSHORT_DELAY );
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179 /* Set the display control. */
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180 PMDIN1 = lcdDISPLAY_CONTROL;
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181 vTaskDelay( lcdSHORT_DELAY );
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183 /* Clear the display. */
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184 PMDIN1 = lcdCLEAR_DISPLAY;
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185 vTaskDelay( lcdSHORT_DELAY );
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187 /* Set the entry mode. */
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188 PMDIN1 = lcdENTRY_MODE;
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189 vTaskDelay( lcdSHORT_DELAY );
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191 /*-----------------------------------------------------------*/
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193 static void vLCDTask( void *pvParameters )
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195 xLCDMessage xMessage;
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196 unsigned portSHORT usRow = 0;
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198 /* Initialise the hardware. This uses delays so must not be called prior
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199 to the scheduler being started. */
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202 /* Welcome message. */
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203 prvLCDPutString( "www.FreeRTOS.org" );
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207 /* Wait for a message to arrive that requires displaying. */
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208 while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
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210 /* Clear the current display value. */
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213 /* Switch rows each time so we can see that the display is still being
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215 prvLCDGotoRow( usRow & 0x01 );
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217 prvLCDPutString( xMessage.pcMessage );
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219 /* Delay the requested amount of time to ensure the text just written
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220 to the LCD is not overwritten. */
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221 vTaskDelay( xMessage.xMinDisplayTime );
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