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349 lines
9.5 KiB
C
349 lines
9.5 KiB
C
/*
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FreeRTOS.org V5.3.1 - Copyright (C) 2003-2009 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License (version 2) as published
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by the Free Software Foundation and modified by the FreeRTOS exception.
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**NOTE** The exception to the GPL is included to allow you to distribute a
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combined work that includes FreeRTOS.org without being obliged to provide
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the source code for any proprietary components. Alternative commercial
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license and support terms are also available upon request. See the
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licensing section of http://www.FreeRTOS.org for full details.
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FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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You should have received a copy of the GNU General Public License along
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with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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***************************************************************************
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* *
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* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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* *
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* This is a concise, step by step, 'hands on' guide that describes both *
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* general multitasking concepts and FreeRTOS specifics. It presents and *
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* explains numerous examples that are written using the FreeRTOS API. *
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* Full source code for all the examples is provided in an accompanying *
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* .zip file. *
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* *
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***************************************************************************
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1 tab == 4 spaces!
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Please ensure to read the configuration and relevant port sections of the
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online documentation.
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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#include "queue.h"
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/* Demo includes. */
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#include "lcd.h"
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/*
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* The LCD is written to by more than one task so is controlled by this
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* 'gatekeeper' task. This is the only task that is actually permitted to
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* access the LCD directly. Other tasks wanting to display a message send
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* the message to the gatekeeper.
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*/
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static void vLCDTask( void *pvParameters );
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/*
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* Setup the peripherals required to communicate with the LCD.
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*/
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static void prvSetupLCD( void );
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/*
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* Move to the first (0) or second (1) row of the LCD.
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*/
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static void prvLCDGotoRow( unsigned portSHORT usRow );
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/*
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* Write a string of text to the LCD.
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*/
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static void prvLCDPutString( portCHAR *pcString );
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/*
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* Clear the LCD.
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*/
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static void prvLCDClear( void );
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/*-----------------------------------------------------------*/
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/* Brief delay to permit the LCD to catch up with commands. */
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#define lcdVERY_SHORT_DELAY ( 1 )
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#define lcdSHORT_DELAY ( 4 / portTICK_RATE_MS )
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#define lcdLONG_DELAY ( 15 / portTICK_RATE_MS )
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/* LCD commands. */
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#define lcdCLEAR ( 0x01 )
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#define lcdHOME ( 0x02 )
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#define lcdLINE2 ( 0xc0 )
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/* SFR that seems to be missing from the standard header files. */
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#define PMAEN *( ( unsigned short * ) 0x60c )
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/* LCD R/W signal. */
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#define lcdRW LATDbits.LATD5
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/* LCD lcdRS signal. */
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#define lcdRS LATBbits.LATB15
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/* LCD lcdE signal . */
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#define lcdE LATDbits.LATD4
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/* Control signal pin direction. */
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#define RW_TRIS TRISDbits.TRISD5
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#define RS_TRIS TRISBbits.TRISB15
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#define E_TRIS TRISDbits.TRISD4
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/* Port for LCD data */
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#define lcdDATA LATE
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#define lcdDATAPORT PORTE
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/* I/O setup for data Port. */
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#define TRISDATA TRISE
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/* The length of the queue used to send messages to the LCD gatekeeper task. */
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#define lcdQUEUE_SIZE 3
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/*-----------------------------------------------------------*/
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/* The queue used to send messages to the LCD task. */
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xQueueHandle xLCDQueue;
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static void prvLCDCommand( portCHAR cCommand );
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static void prvLCDData( portCHAR cChar );
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/*-----------------------------------------------------------*/
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xQueueHandle xStartLCDTask( void )
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{
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/* Create the queue used by the LCD task. Messages for display on the LCD
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are received via this queue. */
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xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
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/* Start the task that will write to the LCD. The LCD hardware is
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initialised from within the task itself so delays can be used. */
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xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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return xLCDQueue;
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}
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/*-----------------------------------------------------------*/
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static void prvLCDGotoRow( unsigned portSHORT usRow )
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{
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if( usRow == 0 )
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{
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prvLCDCommand( lcdHOME );
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}
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else
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{
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prvLCDCommand( lcdLINE2 );
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}
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}
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/*-----------------------------------------------------------*/
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static void prvLCDCommand( portCHAR cCommand )
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{
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/* Prepare RD0 - RD7. */
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lcdDATA &= 0xFF00;
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/* Command byte to lcd. */
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lcdDATA |= cCommand;
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/* Ensure lcdRW is 0. */
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lcdRW = 0;
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lcdRS = 0;
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/* Toggle lcdE line. */
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lcdE = 1;
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vTaskDelay( lcdVERY_SHORT_DELAY );
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lcdE = 0;
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vTaskDelay( lcdSHORT_DELAY );
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}
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/*-----------------------------------------------------------*/
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static void prvLCDData( portCHAR cChar )
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{
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/* ensure lcdRW is 0. */
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lcdRW = 0;
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/* Assert register select to 1. */
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lcdRS = 1;
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/* Prepare RD0 - RD7. */
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lcdDATA &= 0xFF00;
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/* Data byte to lcd. */
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lcdDATA |= cChar;
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lcdE = 1;
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Nop();
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Nop();
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Nop();
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/* Toggle lcdE signal. */
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lcdE = 0;
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/* Negate register select to 0. */
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lcdRS = 0;
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vTaskDelay( lcdVERY_SHORT_DELAY );
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}
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/*-----------------------------------------------------------*/
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static void prvLCDPutString( portCHAR *pcString )
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{
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/* Write out each character with appropriate delay between each. */
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while( *pcString )
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{
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prvLCDData( *pcString );
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pcString++;
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vTaskDelay( lcdSHORT_DELAY );
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}
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}
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/*-----------------------------------------------------------*/
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static void prvLCDClear( void )
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{
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prvLCDCommand( lcdCLEAR );
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}
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/*-----------------------------------------------------------*/
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static void prvSetupLCD( void )
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{
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/* Wait for proper power up. */
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vTaskDelay( lcdLONG_DELAY );
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/* Set initial states for the data and control pins */
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LATE &= 0xFF00;
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/* R/W state set low. */
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lcdRW = 0;
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/* lcdRS state set low. */
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lcdRS = 0;
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/* lcdE state set low. */
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lcdE = 0;
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/* Set data and control pins to outputs */
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TRISE &= 0xFF00;
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/* lcdRW pin set as output. */
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RW_TRIS = 0;
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/* lcdRS pin set as output. */
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RS_TRIS = 0;
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/* lcdE pin set as output. */
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E_TRIS = 0;
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/* 1st LCD initialization sequence */
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lcdDATA &= 0xFF00;
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lcdDATA |= 0x0038;
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lcdE = 1;
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Nop();
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Nop();
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Nop();
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/* Toggle lcdE signal. */
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lcdE = 0;
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vTaskDelay( lcdSHORT_DELAY );
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vTaskDelay( lcdSHORT_DELAY );
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vTaskDelay( lcdSHORT_DELAY );
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/* 2nd LCD initialization sequence */
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lcdDATA &= 0xFF00;
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lcdDATA |= 0x0038;
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lcdE = 1;
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Nop();
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Nop();
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Nop();
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/* Toggle lcdE signal. */
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lcdE = 0;
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vTaskDelay( lcdSHORT_DELAY );
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/* 3rd LCD initialization sequence */
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lcdDATA &= 0xFF00;
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lcdDATA |= 0x0038;
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lcdE = 1;
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Nop();
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Nop();
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Nop();
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/* Toggle lcdE signal. */
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lcdE = 0;
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vTaskDelay( lcdSHORT_DELAY );
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/* Function set. */
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prvLCDCommand( 0x38 );
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/* Display on/off control, cursor blink off (0x0C). */
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prvLCDCommand( 0x0C );
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/* Entry mode set (0x06). */
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prvLCDCommand( 0x06 );
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prvLCDCommand( lcdCLEAR );
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}
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/*-----------------------------------------------------------*/
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static void vLCDTask( void *pvParameters )
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{
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xLCDMessage xMessage;
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unsigned portSHORT usRow = 0;
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/* Initialise the hardware. This uses delays so must not be called prior
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to the scheduler being started. */
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prvSetupLCD();
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/* Welcome message. */
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prvLCDPutString( "www.FreeRTOS.org" );
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for( ;; )
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{
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/* Wait for a message to arrive that requires displaying. */
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while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
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/* Clear the current display value. */
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prvLCDClear();
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/* Switch rows each time so we can see that the display is still being
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updated. */
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prvLCDGotoRow( usRow & 0x01 );
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usRow++;
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prvLCDPutString( xMessage.pcMessage );
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/* Delay the requested amount of time to ensure the text just written
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to the LCD is not overwritten. */
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vTaskDelay( xMessage.xMinDisplayTime );
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}
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}
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