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/*
FreeRTOS.org V5.2.0 - 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 (version 2) as published
by the Free Software Foundation and modified by the FreeRTOS exception.
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 is included to allow you 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.
***************************************************************************
* *
* 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. *
* *
***************************************************************************
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.
*/
/*
* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
*
* This file only supports UART 2
*/
/* Standard includes. */
#include <stdlib.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
/* Demo application includes. */
#include "serial.h"
/* The queue used to hold received characters. */
static xQueueHandle xRxedChars;
/* The queue used to hold characters waiting transmission. */
static xQueueHandle xCharsForTx;
static volatile portSHORT sTHREEmpty;
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
portENTER_CRITICAL();
{
/* Create the queues used by the com test task. */
xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
/* Initialize UART asynchronous mode */
BGR02 = configPER_CLOCK_HZ / ulWantedBaud;
SCR02 = 0x17; /* 8N1 */
SMR02 = 0x0d; /* enable SOT3, Reset, normal mode */
SSR02 = 0x02; /* LSB first, enable receive interrupts */
PFR20_D0 = 1; /* enable UART */
PFR20_D1 = 1; /* enable UART */
EPFR20_D1 = 0; /* enable UART */
}
portEXIT_CRITICAL();
/* Unlike other ports, this serial code does not allow for more than one
com port. We therefore don't return a pointer to a port structure and can
instead just return NULL. */
return NULL;
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
{
/* Get the next character from the buffer. 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 )
{
signed portBASE_TYPE xReturn;
/* Transmit a character. */
portENTER_CRITICAL();
{
if( sTHREEmpty == pdTRUE )
{
/* If sTHREEmpty is true then the UART Tx ISR has indicated that
there are no characters queued to be transmitted - so we can
write the character directly to the shift Tx register. */
sTHREEmpty = pdFALSE;
TDR02 = cOutChar;
xReturn = pdPASS;
}
else
{
/* sTHREEmpty is false, so there are still characters waiting to be
transmitted. We have to queue this character so it gets
transmitted in turn. */
/* Return false if after the block time there is no room on the Tx
queue. It is ok to block inside a critical section as each task
maintains it's own critical section status. */
if (xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) == pdTRUE)
{
xReturn = pdPASS;
}
else
{
xReturn = pdFAIL;
}
}
if (pdPASS == xReturn)
{
/* 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. */
SSR02_TIE = 1;
}
}
portEXIT_CRITICAL();
return pdPASS;
}
/*-----------------------------------------------------------*/
/*
* UART RX interrupt service routine.
*/
__interrupt void UART2_RxISR (void)
{
signed portCHAR cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
/* Get the character from the UART and post it on the queue of Rxed
characters. */
cChar = RDR02;
xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
if( xHigherPriorityTaskWoken )
{
/*If the post causes a task to wake force a context switch
as the woken task may have a higher priority than the task we have
interrupted. */
portYIELD_FROM_ISR();
}
}
/*-----------------------------------------------------------*/
/*
* UART Tx interrupt service routine.
*/
__interrupt void UART2_TxISR (void)
{
signed portCHAR cChar;
signed portBASE_TYPE xTaskWoken = pdFALSE;
/* The previous character has been transmitted. See if there are any
further characters waiting transmission. */
if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xTaskWoken ) == pdTRUE )
{
/* There was another character queued - transmit it now. */
TDR02 = cChar;
}
else
{
/* There were no other characters to transmit. */
sTHREEmpty = pdTRUE;
/* Disable transmit interrupts */
SSR02_TIE = 0;
}
}
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