Demo/dsPIC_MPLAB/lcd.c - third_party/github/FreeRTOS/FreeRTOS-Kernel - Git at Google

 /*
 	FreeRTOS V5.4.1 - 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.


 	***************************************************************************
 	*                                                                         *
 	* Looking for a quick start?  Then check out the FreeRTOS eBook!          *
 	* 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.

 	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 );
 	}
 }
	/*
	FreeRTOS V5.4.1 - 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.


	***************************************************************************
	* *
	* Looking for a quick start? Then check out the FreeRTOS eBook! *
	* 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.

	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 );
	}
	}