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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 UART0.
Note this driver is used to test the FreeRTOS port. It is NOT intended to
be an example of an efficient implementation!
*/
/* Standard includes. */
#include <stdlib.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
/* Demo application includes. */
#include "serial.h"
/*-----------------------------------------------------------*/
/* Constants to setup and access the UART. */
#define serDLAB ( ( unsigned portCHAR ) 0x80 )
#define serENABLE_INTERRUPTS ( ( unsigned portCHAR ) 0x03 )
#define serNO_PARITY ( ( unsigned portCHAR ) 0x00 )
#define ser1_STOP_BIT ( ( unsigned portCHAR ) 0x00 )
#define ser8_BIT_CHARS ( ( unsigned portCHAR ) 0x03 )
#define serFIFO_ON ( ( unsigned portCHAR ) 0x01 )
#define serCLEAR_FIFO ( ( unsigned portCHAR ) 0x06 )
#define serWANTED_CLOCK_SCALING ( ( unsigned portLONG ) 16 )
/* Constants to setup and access the VIC. */
#define serU1VIC_CHANNEL ( ( unsigned portLONG ) 0x0007 )
#define serU1VIC_CHANNEL_BIT ( ( unsigned portLONG ) 0x0080 )
#define serU1VIC_ENABLE ( ( unsigned portLONG ) 0x0020 )
/* Misc. */
#define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
#define serHANDLE ( ( xComPortHandle ) 1 )
#define serNO_BLOCK ( ( portTickType ) 0 )
/* Constant to access the VIC. */
#define serCLEAR_VIC_INTERRUPT ( ( unsigned portLONG ) 0 )
/* Constants to determine the ISR source. */
#define serSOURCE_THRE ( ( unsigned portCHAR ) 0x02 )
#define serSOURCE_RX_TIMEOUT ( ( unsigned portCHAR ) 0x0c )
#define serSOURCE_ERROR ( ( unsigned portCHAR ) 0x06 )
#define serSOURCE_RX ( ( unsigned portCHAR ) 0x04 )
#define serINTERRUPT_SOURCE_MASK ( ( unsigned portCHAR ) 0x0f )
#define serINTERRUPT_IS_PENDING ( ( unsigned portCHAR ) 0x01 )
/*-----------------------------------------------------------*/
/*
* The asm wrapper for the interrupt service routine.
*/
extern void vUART_ISREntry( void );
/*
* The C function called from the asm wrapper.
*/
void vUART_ISRHandler( void );
/*-----------------------------------------------------------*/
/* Queues used to hold received characters, and characters waiting to be
transmitted. */
static xQueueHandle xRxedChars;
static xQueueHandle xCharsForTx;
/* Communication flag between the interrupt service routine and serial API. */
static volatile portLONG lTHREEmpty;
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned portLONG ulDivisor, ulWantedClock;
xComPortHandle xReturn = serHANDLE;
/* Create the queues used to hold Rx and Tx characters. */
xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
/* Initialise the THRE empty flag. */
lTHREEmpty = pdTRUE;
if(
( xRxedChars != serINVALID_QUEUE ) &&
( xCharsForTx != serINVALID_QUEUE ) &&
( ulWantedBaud != ( unsigned portLONG ) 0 )
)
{
portENTER_CRITICAL()
{
/* Setup the baud rate: Calculate the divisor value. */
ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING;
ulDivisor = configCPU_CLOCK_HZ / ulWantedClock;
/* Set the DLAB bit so we can access the divisor. */
U1LCR |= serDLAB;
/* Setup the divisor. */
U1DLL = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
ulDivisor >>= 8;
U1DLM = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
/* Turn on the FIFO's and clear the buffers. */
U1FCR = ( serFIFO_ON | serCLEAR_FIFO );
/* Setup transmission format. */
U1LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS;
/* Setup the VIC for the UART. */
VICIntSelect &= ~( serU1VIC_CHANNEL_BIT );
VICIntEnable |= serU1VIC_CHANNEL_BIT;
VICVectAddr1 = ( unsigned portLONG ) vUART_ISREntry;
VICVectCntl1 = serU1VIC_CHANNEL | serU1VIC_ENABLE;
/* Enable UART0 interrupts. */
U1IER |= serENABLE_INTERRUPTS;
}
portEXIT_CRITICAL();
}
else
{
xReturn = ( xComPortHandle ) 0;
}
return xReturn;
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
{
/* The port handle is not required as this driver only supports UART0. */
( void ) pxPort;
/* 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;
}
}
/*-----------------------------------------------------------*/
void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
{
signed portCHAR *pxNext;
/* NOTE: This implementation does not handle the queue being full as no
block time is used! */
/* The port handle is not required as this driver only supports UART0. */
( void ) pxPort;
( void ) usStringLength;
/* Send each character in the string, one at a time. */
pxNext = ( signed portCHAR * ) pcString;
while( *pxNext )
{
xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
pxNext++;
}
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
{
signed portBASE_TYPE xReturn;
/* The port handle is not required as this driver only supports UART0. */
( void ) pxPort;
portENTER_CRITICAL();
{
/* Is there space to write directly to the UART? */
if( lTHREEmpty == ( portLONG ) pdTRUE )
{
/* We wrote the character directly to the UART, so was
successful. */
lTHREEmpty = pdFALSE;
U1THR = cOutChar;
xReturn = pdPASS;
}
else
{
/* We cannot write directly to the UART, so queue the character.
Block for a maximum of xBlockTime if there is no space in the
queue. It is ok to block within a critical section as each
task has it's own critical section management. */
xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
/* Depending on queue sizing and task prioritisation: While we
were blocked waiting to post interrupts were not disabled. It is
possible that the serial ISR has emptied the Tx queue, in which
case we need to start the Tx off again. */
if( lTHREEmpty == ( portLONG ) pdTRUE )
{
xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
lTHREEmpty = pdFALSE;
U1THR = cOutChar;
}
}
}
portEXIT_CRITICAL();
return xReturn;
}
/*-----------------------------------------------------------*/
void vUART_ISRHandler( void )
{
signed portCHAR cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
unsigned portCHAR ucInterrupt;
ucInterrupt = U1IIR;
/* The interrupt pending bit is active low. */
while( ( ucInterrupt & serINTERRUPT_IS_PENDING ) == 0 )
{
/* What caused the interrupt? */
switch( ucInterrupt & serINTERRUPT_SOURCE_MASK )
{
case serSOURCE_ERROR : /* Not handling this, but clear the interrupt. */
cChar = U1LSR;
break;
case serSOURCE_THRE : /* The THRE is empty. If there is another
character in the Tx queue, send it now. */
if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
{
U1THR = cChar;
}
else
{
/* There are no further characters
queued to send so we can indicate
that the THRE is available. */
lTHREEmpty = pdTRUE;
}
break;
case serSOURCE_RX_TIMEOUT :
case serSOURCE_RX : /* A character was received. Place it in
the queue of received characters. */
cChar = U1RBR;
xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
break;
default : /* There is nothing to do, leave the ISR. */
break;
}
ucInterrupt = U1IIR;
}
/* Clear the ISR in the VIC. */
VICVectAddr = serCLEAR_VIC_INTERRUPT;
/* Exit the ISR. If a task was woken by either a character being received
or transmitted then a context switch will occur. */
portEXIT_SWITCHING_ISR( xHigherPriorityTaskWoken );
}
/*-----------------------------------------------------------*/
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