/*
FreeRTOS V7.0.2 - Copyright (C) 2011 Real Time Engineers Ltd.
***************************************************************************
* *
* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
* *
* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
* *
* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
* *
* Thank you for using FreeRTOS, and thank you for your support! *
* *
***************************************************************************
This file is part of the FreeRTOS distribution.
FreeRTOS is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License (version 2) as published by the
Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
>>>NOTE<<< The modification to the GPL is included to allow you to
distribute a combined work that includes FreeRTOS without being obliged to
provide the source code for proprietary components outside of the FreeRTOS
kernel. FreeRTOS 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 and the FreeRTOS license exception along with FreeRTOS; if not it
can be viewed here: http://www.freertos.org/a00114.html and also obtained
by writing to Richard Barry, contact details for whom are available on the
FreeRTOS WEB site.
1 tab == 4 spaces!
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 );
}
}