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FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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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.
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details. You should have received a copy of the GNU General Public License
and the FreeRTOS license exception along with FreeRTOS; if not it can be
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*************************************************************************** - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details. - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, and our new
fully thread aware and reentrant UDP/IP stack. - Real Time Engineers ltd license FreeRTOS to High
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engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
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 long ) 0 )
/* Constants to determine the ISR source. */
#define serSOURCE_THRE ( ( unsigned char ) 0x02 )
#define serSOURCE_RX_TIMEOUT ( ( unsigned char ) 0x0c )
#define serSOURCE_ERROR ( ( unsigned char ) 0x06 )
#define serSOURCE_RX ( ( unsigned char ) 0x04 )
#define serINTERRUPT_SOURCE_MASK ( ( unsigned long ) (US_RXRDY | US_TXRDY | US_RXBRK | US_OVRE | US_FRAME | US_PARE) )
/* 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 ) __attribute__ ((noinline));
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 char ) );
xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
/* 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. */
__asm volatile( "bl vUART_ISR_Handler" );
/* 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 char cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
unsigned long 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 )