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/*
FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FreeRTOS.org is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FreeRTOS.org; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
***************************************************************************
* *
* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
* *
* This is a concise, step by step, 'hands on' guide that describes both *
* general multitasking concepts and FreeRTOS specifics. It presents and *
* explains numerous examples that are written using the FreeRTOS API. *
* Full source code for all the examples is provided in an accompanying *
* .zip file. *
* *
***************************************************************************
***************************************************************************
Please ensure to read the configuration and relevant port sections of the
online documentation.
http://www.FreeRTOS.org - Documentation, latest information, license and
contact details.
http://www.SafeRTOS.com - A version that is certified for use in safety
critical systems.
http://www.OpenRTOS.com - Commercial support, development, porting,
licensing and training services.
*/
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
/* Demo includes. */
#include "lcd.h"
/*
* The LCD is written to by more than one task so is controlled by this
* 'gatekeeper' task. This is the only task that is actually permitted to
* access the LCD directly. Other tasks wanting to display a message send
* the message to the gatekeeper.
*/
static void vLCDTask( void *pvParameters );
/*
* Setup the peripherals required to communicate with the LCD.
*/
static void prvSetupLCD( void );
/*
* Move to the first (0) or second (1) row of the LCD.
*/
static void prvLCDGotoRow( unsigned portSHORT usRow );
/*
* Write a string of text to the LCD.
*/
static void prvLCDPutString( portCHAR *pcString );
/*
* Clear the LCD.
*/
static void prvLCDClear( void );
/*-----------------------------------------------------------*/
/* Brief delay to permit the LCD to catch up with commands. */
#define lcdVERY_SHORT_DELAY ( 1 )
#define lcdSHORT_DELAY ( 4 / portTICK_RATE_MS )
#define lcdLONG_DELAY ( 15 / portTICK_RATE_MS )
/* LCD commands. */
#define lcdCLEAR ( 0x01 )
#define lcdHOME ( 0x02 )
#define lcdLINE2 ( 0xc0 )
/* SFR that seems to be missing from the standard header files. */
#define PMAEN *( ( unsigned short * ) 0x60c )
/* LCD R/W signal. */
#define lcdRW LATDbits.LATD5
/* LCD lcdRS signal. */
#define lcdRS LATBbits.LATB15
/* LCD lcdE signal . */
#define lcdE LATDbits.LATD4
/* Control signal pin direction. */
#define RW_TRIS TRISDbits.TRISD5
#define RS_TRIS TRISBbits.TRISB15
#define E_TRIS TRISDbits.TRISD4
/* Port for LCD data */
#define lcdDATA LATE
#define lcdDATAPORT PORTE
/* I/O setup for data Port. */
#define TRISDATA TRISE
/* The length of the queue used to send messages to the LCD gatekeeper task. */
#define lcdQUEUE_SIZE 3
/*-----------------------------------------------------------*/
/* The queue used to send messages to the LCD task. */
xQueueHandle xLCDQueue;
static void prvLCDCommand( portCHAR cCommand );
static void prvLCDData( portCHAR cChar );
/*-----------------------------------------------------------*/
xQueueHandle xStartLCDTask( void )
{
/* Create the queue used by the LCD task. Messages for display on the LCD
are received via this queue. */
xLCDQueue = xQueueCreate( lcdQUEUE_SIZE, sizeof( xLCDMessage ) );
/* Start the task that will write to the LCD. The LCD hardware is
initialised from within the task itself so delays can be used. */
xTaskCreate( vLCDTask, ( signed portCHAR * ) "LCD", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
return xLCDQueue;
}
/*-----------------------------------------------------------*/
static void prvLCDGotoRow( unsigned portSHORT usRow )
{
if( usRow == 0 )
{
prvLCDCommand( lcdHOME );
}
else
{
prvLCDCommand( lcdLINE2 );
}
}
/*-----------------------------------------------------------*/
static void prvLCDCommand( portCHAR cCommand )
{
/* Prepare RD0 - RD7. */
lcdDATA &= 0xFF00;
/* Command byte to lcd. */
lcdDATA |= cCommand;
/* Ensure lcdRW is 0. */
lcdRW = 0;
lcdRS = 0;
/* Toggle lcdE line. */
lcdE = 1;
vTaskDelay( lcdVERY_SHORT_DELAY );
lcdE = 0;
vTaskDelay( lcdSHORT_DELAY );
}
/*-----------------------------------------------------------*/
static void prvLCDData( portCHAR cChar )
{
/* ensure lcdRW is 0. */
lcdRW = 0;
/* Assert register select to 1. */
lcdRS = 1;
/* Prepare RD0 - RD7. */
lcdDATA &= 0xFF00;
/* Data byte to lcd. */
lcdDATA |= cChar;
lcdE = 1;
Nop();
Nop();
Nop();
/* Toggle lcdE signal. */
lcdE = 0;
/* Negate register select to 0. */
lcdRS = 0;
vTaskDelay( lcdVERY_SHORT_DELAY );
}
/*-----------------------------------------------------------*/
static void prvLCDPutString( portCHAR *pcString )
{
/* Write out each character with appropriate delay between each. */
while( *pcString )
{
prvLCDData( *pcString );
pcString++;
vTaskDelay( lcdSHORT_DELAY );
}
}
/*-----------------------------------------------------------*/
static void prvLCDClear( void )
{
prvLCDCommand( lcdCLEAR );
}
/*-----------------------------------------------------------*/
static void prvSetupLCD( void )
{
/* Wait for proper power up. */
vTaskDelay( lcdLONG_DELAY );
/* Set initial states for the data and control pins */
LATE &= 0xFF00;
/* R/W state set low. */
lcdRW = 0;
/* lcdRS state set low. */
lcdRS = 0;
/* lcdE state set low. */
lcdE = 0;
/* Set data and control pins to outputs */
TRISE &= 0xFF00;
/* lcdRW pin set as output. */
RW_TRIS = 0;
/* lcdRS pin set as output. */
RS_TRIS = 0;
/* lcdE pin set as output. */
E_TRIS = 0;
/* 1st LCD initialization sequence */
lcdDATA &= 0xFF00;
lcdDATA |= 0x0038;
lcdE = 1;
Nop();
Nop();
Nop();
/* Toggle lcdE signal. */
lcdE = 0;
vTaskDelay( lcdSHORT_DELAY );
vTaskDelay( lcdSHORT_DELAY );
vTaskDelay( lcdSHORT_DELAY );
/* 2nd LCD initialization sequence */
lcdDATA &= 0xFF00;
lcdDATA |= 0x0038;
lcdE = 1;
Nop();
Nop();
Nop();
/* Toggle lcdE signal. */
lcdE = 0;
vTaskDelay( lcdSHORT_DELAY );
/* 3rd LCD initialization sequence */
lcdDATA &= 0xFF00;
lcdDATA |= 0x0038;
lcdE = 1;
Nop();
Nop();
Nop();
/* Toggle lcdE signal. */
lcdE = 0;
vTaskDelay( lcdSHORT_DELAY );
/* Function set. */
prvLCDCommand( 0x38 );
/* Display on/off control, cursor blink off (0x0C). */
prvLCDCommand( 0x0C );
/* Entry mode set (0x06). */
prvLCDCommand( 0x06 );
prvLCDCommand( lcdCLEAR );
}
/*-----------------------------------------------------------*/
static void vLCDTask( void *pvParameters )
{
xLCDMessage xMessage;
unsigned portSHORT usRow = 0;
/* Initialise the hardware. This uses delays so must not be called prior
to the scheduler being started. */
prvSetupLCD();
/* Welcome message. */
prvLCDPutString( "www.FreeRTOS.org" );
for( ;; )
{
/* Wait for a message to arrive that requires displaying. */
while( xQueueReceive( xLCDQueue, &xMessage, portMAX_DELAY ) != pdPASS );
/* Clear the current display value. */
prvLCDClear();
/* Switch rows each time so we can see that the display is still being
updated. */
prvLCDGotoRow( usRow & 0x01 );
usRow++;
prvLCDPutString( xMessage.pcMessage );
/* Delay the requested amount of time to ensure the text just written
to the LCD is not overwritten. */
vTaskDelay( xMessage.xMinDisplayTime );
}
}
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