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/*
FreeRTOS.org V5.1.2 - 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 as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
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 can be applied should you wish 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 of how and when the exception
can be applied.
***************************************************************************
***************************************************************************
* *
* 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. *
* *
***************************************************************************
***************************************************************************
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.
*/
/* Standard includes. */
#include <stdlib.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "queue.h"
/* Demo application includes. */
#include "serial.h"
/* Atmel library includes. */
#include <usart/usart.h>
#include <aic/aic.h>
#include <pmc/pmc.h>
/*-----------------------------------------------------------*/
/* Location of the COM0 registers. */
#define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
/* Interrupt control macros. */
#define serINTERRUPT_LEVEL ( 5 )
#define vInterruptOn() serCOM0->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )
#define vInterruptOff() serCOM0->US_IDR = AT91C_US_TXRDY
/* Misc constants. */
#define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
#define serHANDLE ( ( xComPortHandle ) 1 )
#define serNO_BLOCK ( ( portTickType ) 0 )
#define serNO_TIMEGUARD ( ( unsigned portLONG ) 0 )
#define serNO_PERIPHERAL_B_SETUP ( ( unsigned portLONG ) 0 )
/* Queues used to hold received characters, and characters waiting to be
transmitted. */
static xQueueHandle xRxedChars;
static xQueueHandle xCharsForTx;
/*-----------------------------------------------------------*/
/* The interrupt service routine. */
__arm void vSerialISR( void );
/*-----------------------------------------------------------*/
/*
* See the serial2.h header file.
*/
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
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 ) );
/* If the queues were created correctly then setup the serial port
hardware. */
if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
{
PMC_EnablePeripheral( AT91C_ID_US0 );
portENTER_CRITICAL();
{
USART_Configure( serCOM0, ( AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE ), ulWantedBaud, configCPU_CLOCK_HZ );
/* Enable Rx and Tx. */
USART_SetTransmitterEnabled( serCOM0, pdTRUE );
USART_SetReceiverEnabled( serCOM0, pdTRUE );
/* Enable the Rx interrupts. The Tx interrupts are not enabled
until there are characters to be transmitted. */
serCOM0->US_IER = AT91C_US_RXRDY;
/* Enable the interrupts in the AIC. */
AIC_ConfigureIT( AT91C_ID_US0, AT91C_AIC_PRIOR_LOWEST, ( void (*)( void ) ) vSerialISR );
AIC_EnableIT( AT91C_ID_US0 );
}
portEXIT_CRITICAL();
}
else
{
xReturn = ( xComPortHandle ) 0;
}
/* This demo file only supports a single port but we have to return
something to comply with the standard demo header file. */
return xReturn;
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
{
/* The port handle is not required as this driver only supports one port. */
( 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;
/* A couple of parameters that this port does not use. */
( void ) usStringLength;
( void ) pxPort;
/* 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;
/* 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 )
{
/* Just to remove compiler warning. */
( void ) pxPort;
/* 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. */
vInterruptOn();
return pdPASS;
}
/*-----------------------------------------------------------*/
void vSerialClose( xComPortHandle xPort )
{
/* Not supported as not required by the demo application. */
( void ) xPort;
}
/*-----------------------------------------------------------*/
/* Serial port ISR. This can cause a context switch so is not defined as a
standard ISR using the __irq keyword. Instead a wrapper function is defined
within serialISR.s79 which in turn calls this function. See the port
documentation on the FreeRTOS.org website for more information. */
__arm void vSerialISR( void )
{
unsigned portLONG ulStatus;
signed portCHAR cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
/* What caused the interrupt? */
ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
if( ulStatus & AT91C_US_TXRDY )
{
/* The interrupt was caused by the THR becoming empty. Are there any
more characters to transmit? */
if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
{
/* A character was retrieved from the queue so can be sent to the
THR now. */
serCOM0->US_THR = cChar;
}
else
{
/* Queue empty, nothing to send so turn off the Tx interrupt. */
vInterruptOff();
}
}
if( ulStatus & AT91C_US_RXRDY )
{
/* The interrupt was caused by a character being received. Grab the
character from the RHR and place it in the queue or received
characters. */
cChar = serCOM0->US_RHR;
xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
}
/* If a task was woken by either a character being received or a character
being transmitted then we may need to switch to another task. */
portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
/* End the interrupt in the AIC. */
AT91C_BASE_AIC->AIC_EOICR = 0;
}
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