Demo/PIC32MX_MPLAB/lcd.c

/*
    FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.

    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 exception 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.
    Alternative commercial license and support terms are also available upon
    request.  See the licensing section of http://www.FreeRTOS.org for full
    license details.

    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 along
    with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
    Temple Place, Suite 330, Boston, MA  02111-1307  USA.


    ***************************************************************************
    *                                                                         *
    * The FreeRTOS eBook and reference manual are available to purchase for a *
    * small fee. Help yourself get started quickly while also helping the     *
    * FreeRTOS project! See http://www.FreeRTOS.org/Documentation for details *
    *                                                                         *
    ***************************************************************************

    1 tab == 4 spaces!

    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.

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*/

/* peripheral library include */
#include <plib.h>

/* 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 specific definitions. */
#define LCD_CLEAR_DISPLAY_CMD			0x01
#define LCD_CURSOR_HOME_CMD				0x02
#define LCD_ENTRY_MODE_CMD				0x04
#define LCD_ENTRY_MODE_INCREASE			0x02
#define LCD_DISPLAY_CTRL_CMD			0x08
#define LCD_DISPLAY_CTRL_DISPLAY_ON		0x04
#define LCD_FUNCTION_SET_CMD			0x20
#define LCD_FUNCTION_SET_8_BITS			0x10
#define LCD_FUNCTION_SET_2_LINES		0x08
#define LCD_FUNCTION_SET_LRG_FONT		0x04
#define LCD_NEW_LINE					0xC0
#define LCD_COMMAND_ADDRESS				0x00
#define LCD_DATA_ADDRESS				0x01

/* 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;

/* LCD access functions. */
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( LCD_CURSOR_HOME_CMD );
	} 
	else 
	{
		prvLCDCommand( LCD_NEW_LINE );
	}
}
/*-----------------------------------------------------------*/

static void prvLCDCommand( portCHAR cCommand ) 
{
	PMPSetAddress( LCD_COMMAND_ADDRESS );
	PMPMasterWrite( cCommand );
   	vTaskDelay( lcdSHORT_DELAY );
}
/*-----------------------------------------------------------*/

static void prvLCDData( portCHAR cChar )
{
	PMPSetAddress( LCD_DATA_ADDRESS );
	PMPMasterWrite( cChar );
	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(LCD_CLEAR_DISPLAY_CMD);
}
/*-----------------------------------------------------------*/

static void prvSetupLCD(void)
{
	/* Wait for proper power up. */
	vTaskDelay( lcdLONG_DELAY );
	
	/* Open the PMP port */
	mPMPOpen((PMP_ON | PMP_READ_WRITE_EN | PMP_CS2_CS1_EN |
			  PMP_LATCH_POL_HI | PMP_CS2_POL_HI | PMP_CS1_POL_HI |
			  PMP_WRITE_POL_HI | PMP_READ_POL_HI),
			 (PMP_MODE_MASTER1 | PMP_WAIT_BEG_4 | PMP_WAIT_MID_15 |
			  PMP_WAIT_END_4),
			  PMP_PEN_0, 0);
			 
	/* Wait for the LCD to power up correctly. */
	vTaskDelay( lcdLONG_DELAY );
	vTaskDelay( lcdLONG_DELAY );
	vTaskDelay( lcdLONG_DELAY );

	/* Set up the LCD function. */
	prvLCDCommand( LCD_FUNCTION_SET_CMD | LCD_FUNCTION_SET_8_BITS | LCD_FUNCTION_SET_2_LINES | LCD_FUNCTION_SET_LRG_FONT );
	
	/* Turn the display on. */
	prvLCDCommand( LCD_DISPLAY_CTRL_CMD | LCD_DISPLAY_CTRL_DISPLAY_ON );
	
	/* Clear the display. */
	prvLCDCommand( LCD_CLEAR_DISPLAY_CMD );
	vTaskDelay( lcdLONG_DELAY );	
	
	/* Increase the cursor. */
	prvLCDCommand( LCD_ENTRY_MODE_CMD | LCD_ENTRY_MODE_INCREASE );
	vTaskDelay( lcdLONG_DELAY );		  	
	vTaskDelay( lcdLONG_DELAY );		  	
	vTaskDelay( lcdLONG_DELAY );
}
/*-----------------------------------------------------------*/

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 );		
	}
}