2 FreeRTOS.org V5.3.1 - 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 it
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7 under the terms of the GNU General Public License (version 2) as published
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8 by the 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.org without being obliged to provide
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11 the source code for any proprietary components. Alternative commercial
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12 license and support terms are also available upon request. See the
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13 licensing section of http://www.FreeRTOS.org for full details.
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15 FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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20 You should have received a copy of the GNU General Public License along
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21 with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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22 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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25 ***************************************************************************
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27 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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29 * This is a concise, step by step, 'hands on' guide that describes both *
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30 * general multitasking concepts and FreeRTOS specifics. It presents and *
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31 * explains numerous examples that are written using the FreeRTOS API. *
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32 * Full source code for all the examples is provided in an accompanying *
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35 ***************************************************************************
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39 Please ensure to read the configuration and relevant port sections of the
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40 online documentation.
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42 http://www.FreeRTOS.org - Documentation, latest information, license and
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45 http://www.SafeRTOS.com - A version that is certified for use in safety
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48 http://www.OpenRTOS.com - Commercial support, development, porting,
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49 licensing and training services.
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52 /* Scheduler includes. */
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53 #include "FreeRTOS.h"
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57 /* Demo includes. */
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61 * The LCD is written to by more than one task so is controlled by this
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62 * 'gatekeeper' task. This is the only task that is actually permitted to
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63 * access the LCD directly. Other tasks wanting to display a message send
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64 * the message to the gatekeeper.
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66 static void vLCDTask( void *pvParameters );
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69 * Setup the peripherals required to communicate with the LCD.
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71 static void prvSetupLCD( void );
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74 * Move to the first (0) or second (1) row of the LCD.
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76 static void prvLCDGotoRow( unsigned portSHORT usRow );
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79 * Write a string of text to the LCD.
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81 static void prvLCDPutString( portCHAR *pcString );
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86 static void prvLCDClear( void );
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88 /*-----------------------------------------------------------*/
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90 /* Brief delay to permit the LCD to catch up with commands. */
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91 #define lcdSHORT_DELAY 3
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93 /* SFR that seems to be missing from the standard header files. */
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94 #define PMAEN *( ( unsigned short * ) 0x60c )
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97 #define lcdDEFAULT_FUNCTION 0x3c
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98 #define lcdDISPLAY_CONTROL 0x0c
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99 #define lcdCLEAR_DISPLAY 0x01
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100 #define lcdENTRY_MODE 0x06
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102 /* The length of the queue used to send messages to the LCD gatekeeper task. */
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103 #define lcdQUEUE_SIZE 3
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104 /*-----------------------------------------------------------*/
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106 /* The queue used to send messages to the LCD task. */
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107 xQueueHandle xLCDQueue;
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110 /*-----------------------------------------------------------*/
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112 xQueueHandle xStartLCDTask( void )
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114 /* Create the queue used by the LCD task. Messages for display on the LCD
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115 are received via this queue. */
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116 xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
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118 /* Start the task that will write to the LCD. The LCD hardware is
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119 initialised from within the task itself so delays can be used. */
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120 xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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124 /*-----------------------------------------------------------*/
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126 static void prvLCDGotoRow( unsigned portSHORT usRow )
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139 vTaskDelay( lcdSHORT_DELAY );
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141 /*-----------------------------------------------------------*/
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143 static void prvLCDPutString( portCHAR *pcString )
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145 /* Write out each character with appropriate delay between each. */
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149 PMDIN1 = *pcString;
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151 vTaskDelay( lcdSHORT_DELAY );
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154 /*-----------------------------------------------------------*/
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156 static void prvLCDClear( void )
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158 /* Clear the display. */
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160 PMDIN1 = lcdCLEAR_DISPLAY;
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161 vTaskDelay( lcdSHORT_DELAY );
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163 /*-----------------------------------------------------------*/
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165 static void prvSetupLCD( void )
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167 /* Setup the PMP. */
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172 vTaskDelay( lcdSHORT_DELAY );
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174 /* Set the default function. */
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175 PMDIN1 = lcdDEFAULT_FUNCTION;
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176 vTaskDelay( lcdSHORT_DELAY );
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178 /* Set the display control. */
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179 PMDIN1 = lcdDISPLAY_CONTROL;
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180 vTaskDelay( lcdSHORT_DELAY );
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182 /* Clear the display. */
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183 PMDIN1 = lcdCLEAR_DISPLAY;
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184 vTaskDelay( lcdSHORT_DELAY );
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186 /* Set the entry mode. */
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187 PMDIN1 = lcdENTRY_MODE;
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188 vTaskDelay( lcdSHORT_DELAY );
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190 /*-----------------------------------------------------------*/
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192 static void vLCDTask( void *pvParameters )
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194 xLCDMessage xMessage;
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195 unsigned portSHORT usRow = 0;
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197 /* Initialise the hardware. This uses delays so must not be called prior
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198 to the scheduler being started. */
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201 /* Welcome message. */
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202 prvLCDPutString( "www.FreeRTOS.org" );
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206 /* Wait for a message to arrive that requires displaying. */
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207 while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
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209 /* Clear the current display value. */
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212 /* Switch rows each time so we can see that the display is still being
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214 prvLCDGotoRow( usRow & 0x01 );
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216 prvLCDPutString( xMessage.pcMessage );
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218 /* Delay the requested amount of time to ensure the text just written
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219 to the LCD is not overwritten. */
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220 vTaskDelay( xMessage.xMinDisplayTime );
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