FreeRTOS-Kernel/Demo/HCS12_CodeWarrior_banked/serial/serial.c

/*
	FreeRTOS V5.4.2 - 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.


	***************************************************************************
	*                                                                         *
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	* See http://www.FreeRTOS.org/Documentation for details                   *
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	***************************************************************************

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	Please ensure to read the configuration and relevant port sections of the
	online documentation.

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*/


/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER for port 1.

Note that this driver is written to test the RTOS port and is not intended
to represent an optimised solution. */

/* Processor Expert generated includes. */
#include "com0.h"

/* Scheduler include files. */
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"

/* Demo application include files. */
#include "serial.h"

/* The queues used to communicate between the task code and the interrupt
service routines. */
static xQueueHandle xRxedChars; 
static xQueueHandle xCharsForTx; 

/* Interrupt identification bits. */
#define serOVERRUN_INTERRUPT		( 0x08 )
#define serRX_INTERRUPT				( 0x20 )
#define serTX_INTERRUPT				( 0x80 )

/*-----------------------------------------------------------*/


/*
 * Initialise port for interrupt driven communications.
 */
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
	/* Hardware setup is performed by the Processor Expert generated code.  
	This function just creates the queues used to communicate between the 
	interrupt code and the task code - then sets the required baud rate. */

	xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
	xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );

	COM0_SetBaudRateMode( ( portCHAR ) ulWantedBaud );

	return NULL;
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
{
	/* Get the next character from the buffer queue.  Return false if no characters
	are available, or arrive before xBlockTime expires. */
	if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
	{
		return pdTRUE;
	}
	else
	{
		return pdFALSE;
	}
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
{
	/* Place the character in the queue of characters to be transmitted. */
	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
	{
		return pdFAIL;
	}

	/* Turn on the Tx interrupt so the ISR will remove the character from the
	queue and send it.   This does not need to be in a critical section as
	if the interrupt has already removed the character the next interrupt
	will simply turn off the Tx interrupt again. */
	SCI0CR2_SCTIE = 1;;

	return pdPASS;
}
/*-----------------------------------------------------------*/

void vSerialClose( xComPortHandle xPort )
{	
	/* Not supported. */
	( void ) xPort;
}
/*-----------------------------------------------------------*/


/* 
 * Interrupt service routine for the serial port.  Must be in non-banked
 * memory. 
 */

#pragma CODE_SEG __NEAR_SEG NON_BANKED

__interrupt void vCOM0_ISR( void )
{
volatile unsigned portCHAR ucByte, ucStatus;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

	/* What caused the interrupt? */
	ucStatus = SCI0SR1;
	
	if( ucStatus & serOVERRUN_INTERRUPT )
	{
		/* The interrupt was caused by an overrun.  Clear the error by reading
		the data register. */
		ucByte = SCI0DRL;
	}

	if( ucStatus & serRX_INTERRUPT )
	{	
		/* The interrupt was caused by a character being received.
		Read the received byte. */
		ucByte = SCI0DRL;                      

		/* Post the character onto the queue of received characters - noting
		whether or not this wakes a task. */
		xQueueSendFromISR( xRxedChars, ( void * ) &ucByte, &xHigherPriorityTaskWoken );
	}
	
	if( ( ucStatus & serTX_INTERRUPT ) && ( SCI0CR2_SCTIE ) )
	{	
		/* The interrupt was caused by a character being transmitted. */
		if( xQueueReceiveFromISR( xCharsForTx, ( void * ) &ucByte, &xHigherPriorityTaskWoken ) == pdTRUE )
		{
			/* Clear the SCRF bit. */
			SCI0DRL = ucByte;
		}
		else
		{
			/* Disable transmit interrupt */
			SCI0CR2_SCTIE = 0;                 
		}
	}

	if( xHigherPriorityTaskWoken )
	{
		portYIELD();
	}
}

#pragma CODE_SEG DEFAULT