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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 for port 1.
Note that this driver is written to test the RTOS port and is not intended
to represent an optimised solution. In particular no use is made of the DMA
peripheral. */
/* Standard include files. */
#include <stdlib.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;
/* Hardware specific constants. */
#define serTX_INTERRUPT ( ( unsigned portCHAR ) 0x80 )
#define serRX_INTERRUPT ( ( unsigned portCHAR ) 0x40 )
#define serTX_ENABLE ( ( unsigned portCHAR ) 0x20 )
#define serRX_ENABLE ( ( unsigned portCHAR ) 0x10 )
/* Macros to turn on and off the serial port THRE interrupt while leaving the
other register bits in their correct state. The Rx interrupt is always
enabled. */
#define serTX_INTERRUPT_ON() SCR1 = serTX_INTERRUPT | serRX_INTERRUPT | serTX_ENABLE | serRX_ENABLE;
#define serTX_INTERRUPT_OFF() SCR1 = serRX_INTERRUPT | serTX_ENABLE | serRX_ENABLE;
/* Bit used to switch on the channel 1 serial port in the module stop
register. */
#define serMSTP6 ( ( unsigned portSHORT ) 0x0040 )
/* Interrupt service routines. Note that the Rx and Tx service routines can
cause a context switch and are therefore defined with the saveall attribute in
addition to the interrupt_handler attribute. See the FreeRTOS.org WEB site
documentation for a full explanation.*/
void vCOM_1_Rx_ISR( void ) __attribute__ ( ( saveall, interrupt_handler ) );
void vCOM_1_Tx_ISR( void ) __attribute__ ( ( saveall, interrupt_handler ) );
void vCOM_1_Error_ISR( void ) __attribute__ ( ( interrupt_handler ) );
/*-----------------------------------------------------------*/
/*
* Initialise port 1 for interrupt driven communications.
*/
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
/* Create the queues used to communicate between the tasks and the
interrupt service routines. */
xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
/* No parity, 8 data bits and 1 stop bit is the default so does not require
configuration - setup the remains of the hardware. */
portENTER_CRITICAL();
{
/* Turn channel 1 on. */
MSTPCR &= ~serMSTP6;
/* Enable the channels and the Rx interrupt. The Tx interrupt is only
enabled when data is being transmitted. */
SCR1 = serRX_INTERRUPT | serTX_ENABLE | serRX_ENABLE;
/* Bit rate settings for 22.1184MHz clock only!. */
switch( ulWantedBaud )
{
case 4800 : BRR1 = 143;
break;
case 9600 : BRR1 = 71;
break;
case 19200 : BRR1 = 35;
break;
case 38400 : BRR1 = 17;
break;
case 57600 : BRR1 = 11;
break;
case 115200 : BRR1 = 5;
break;
default : BRR1 = 5;
break;
}
}
portEXIT_CRITICAL();
/* Unlike some ports, this driver 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 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 )
{
signed portBASE_TYPE xReturn = pdPASS;
/* Return false if after the block time there is no room on the Tx queue. */
portENTER_CRITICAL();
{
/* Send a character to the queue of characters waiting transmission.
The queue is serviced by the Tx ISR. */
if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
{
/* Could not post onto the queue. */
xReturn = pdFAIL;
}
else
{
/* The message was posted onto the queue so we turn on the Tx
interrupt to allow the Tx ISR to remove the character from the
queue. */
serTX_INTERRUPT_ON();
}
}
portEXIT_CRITICAL();
return xReturn;
}
/*-----------------------------------------------------------*/
void vSerialClose( xComPortHandle xPort )
{
/* Not supported. */
( void ) xPort;
}
/*-----------------------------------------------------------*/
void vCOM_1_Rx_ISR( void )
{
/* This can cause a context switch so this macro must be the first line
in the function. */
portENTER_SWITCHING_ISR();
/* As this is a switching ISR the local variables must be declared as
static. */
static portCHAR cRxByte;
static portBASE_TYPE xHigherPriorityTaskWoken;
xHigherPriorityTaskWoken = pdFALSE;
/* Get the character. */
cRxByte = RDR1;
/* Post the character onto the queue of received characters - noting
whether or not this wakes a task. */
xQueueSendFromISR( xRxedChars, &cRxByte, &xHigherPriorityTaskWoken );
/* Clear the interrupt. */
SSR1 &= ~serRX_INTERRUPT;
/* This must be the last line in the function. We pass cTaskWokenByPost so
a context switch will occur if the received character woke a task that has
a priority higher than the task we interrupted. */
portEXIT_SWITCHING_ISR( xHigherPriorityTaskWoken );
}
/*-----------------------------------------------------------*/
void vCOM_1_Tx_ISR( void )
{
/* This can cause a context switch so this macro must be the first line
in the function. */
portENTER_SWITCHING_ISR();
/* As this is a switching ISR the local variables must be declared as
static. */
static portCHAR cTxByte;
static signed portBASE_TYPE xTaskWokenByTx;
/* This variable is static so must be explicitly reinitialised each
time the function executes. */
xTaskWokenByTx = pdFALSE;
/* The interrupt was caused by the THR becoming empty. Are there any
more characters to transmit? Note whether or not the Tx interrupt has
woken a task. */
if( xQueueReceiveFromISR( xCharsForTx, &cTxByte, &xTaskWokenByTx ) == pdTRUE )
{
/* A character was retrieved from the queue so can be sent to the
THR now. */
TDR1 = cTxByte;
/* Clear the interrupt. */
SSR1 &= ~serTX_INTERRUPT;
}
else
{
/* Queue empty, nothing to send so turn off the Tx interrupt. */
serTX_INTERRUPT_OFF();
}
/* This must be the last line in the function. We pass cTaskWokenByTx so
a context switch will occur if the Tx'ed character woke a task that has
a priority higher than the task we interrupted. */
portEXIT_SWITCHING_ISR( xTaskWokenByTx );
}
/*-----------------------------------------------------------*/
/*
* This ISR cannot cause a context switch so requires no special
* considerations.
*/
void vCOM_1_Error_ISR( void )
{
volatile unsigned portCHAR ucIn;
ucIn = SSR1;
SSR1 = 0;
}
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