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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 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.
* *
* Looking for a quick start? Then check out the FreeRTOS eBook! *
* See for details *
* *
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Please ensure to read the configuration and relevant port sections of the
online documentation. - Documentation, latest information, license and
contact details. - A version that is certified for use in safety
critical systems. - Commercial support, development, porting,
licensing and training services.
This file contains all the serial port components that must be compiled
to ARM mode. The components that can be compiled to either ARM or THUMB
mode are contained in serial.c.
/* Standard includes. */
#include <stdlib.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
/* Demo application includes. */
#include "serial.h"
#include "AT91R40008.h"
#include "usart.h"
/* Constant to access the AIC. */
#define serCLEAR_AIC_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 )
/* Queues used to hold received characters, and characters waiting to be
transmitted. */
static xQueueHandle xRxedChars;
static xQueueHandle xCharsForTx;
/* UART0 interrupt service routine. This can cause a context switch so MUST
be declared "naked". */
void vUART_ISR_Wrapper( void ) __attribute__ ((naked));
/* The ISR function that actually performs the work. This must be separate
from the wrapper to ensure the correct stack frame is set up. */
void vUART_ISR_Handler( void );
void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx )
/* 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 ) );
/* Pass back a reference to the queues so the serial API file can
post/receive characters. */
*pxRxedChars = xRxedChars;
*pxCharsForTx = xCharsForTx;
void vUART_ISR_Wrapper( void )
/* Save the context of the interrupted task. */
/* Call the handler. This must be a separate function to ensure the
stack frame is correctly set up. */
/* Restore the context of whichever task will run next. */
void vUART_ISR_Handler( void )
/* Now we can declare the local variables. These must be static. */
signed portCHAR cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
unsigned portLONG ulStatus;
/* What caused the interrupt? */
ulStatus = AT91C_BASE_US0->US_CSR & AT91C_BASE_US0->US_IMR;
if (ulStatus & 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. */
AT91C_BASE_US0->US_THR = cChar;
/* Queue empty, nothing to send so turn off the Tx interrupt. */
if (ulStatus & US_RXRDY)
/* The interrupt was caused by the receiver getting data. */
cChar = AT91C_BASE_US0->US_RHR;
xQueueSendFromISR(xRxedChars, &cChar, &xHigherPriorityTaskWoken);
/* Acknowledge the interrupt at AIC level... */
/* If an event caused a task to unblock then we call "Yield from ISR" to
ensure that the unblocked task is the task that executes when the interrupt
completes if the unblocked task has a priority higher than the interrupted
task. */
if( xHigherPriorityTaskWoken )