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FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
* *
* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
* *
* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
* *
* >>> See for details. <<< *
* *
* Thank you for using FreeRTOS, and thank you for your support! *
* *
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 modification 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
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
and the FreeRTOS license exception along with FreeRTOS; if not it can be
viewed here: and also obtained by
writing to Real Time Engineers Ltd., contact details for whom are available
on the FreeRTOS WEB site.
1 tab == 4 spaces!
* *
* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
* *
* *
* *
*************************************************************************** - 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
Integrity Systems, who sell the code with commercial support,
indemnification and middleware, under the OpenRTOS brand. - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
* Manages a queue of strings that are waiting to be displayed. This is used to
* ensure mutual exclusion of console output.
* A task wishing to display a message will call vPrintDisplayMessage (), with a
* pointer to the string as the parameter. The pointer is posted onto the
* xPrintQueue queue.
* The task spawned in main. c blocks on xPrintQueue. When a message becomes
* available it calls pcPrintGetNextMessage () to obtain a pointer to the next
* string, then uses the functions defined in the portable layer FileIO. c to
* display the message.
* <b>NOTE:</b>
* Using console IO can disrupt real time performance - depending on the port.
* Standard C IO routines are not designed for real time applications. While
* standard IO is useful for demonstration and debugging an alternative method
* should be used if you actually require console IO as part of your application.
* \page PrintC print.c
* \ingroup DemoFiles
* <HR>
Changes from V2.0.0
+ Delay periods are now specified using variables and constants of
portTickType rather than unsigned long.
#include <stdlib.h>
/* Scheduler include files. */
#include "FreeRTOS.h"
#include "queue.h"
/* Demo program include files. */
#include "print.h"
static xQueueHandle xPrintQueue;
void vPrintInitialise( void )
const unsigned portBASE_TYPE uxQueueSize = 20;
/* Create the queue on which errors will be reported. */
xPrintQueue = xQueueCreate( uxQueueSize, ( unsigned portBASE_TYPE ) sizeof( char * ) );
void vPrintDisplayMessage( const char * const * ppcMessageToSend )
#ifdef USE_STDIO
xQueueSend( xPrintQueue, ( void * ) ppcMessageToSend, ( portTickType ) 0 );
/* Stop warnings. */
( void ) ppcMessageToSend;
const char *pcPrintGetNextMessage( portTickType xPrintRate )
char *pcMessage;
if( xQueueReceive( xPrintQueue, &pcMessage, xPrintRate ) == pdPASS )
return pcMessage;
return NULL;