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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.
>>>>>>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.
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* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
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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
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.
* Instead of the normal single demo application, the PIC18F demo is split
* into several smaller programs of which this is the first. This enables the
* demo's to be executed on the RAM limited 40 pin devices. The 64 and 80 pin
* devices require a more costly development platform and are not so readily
* available.
* The RTOSDemo1 project is configured for a PIC18F452 device. Main1.c starts 5
* tasks (including the idle task).
* The first task runs at the idle priority. It repeatedly performs a 32bit
* calculation and checks it's result against the expected value. This checks
* that the temporary storage utilised by the compiler to hold intermediate
* results does not get corrupted when the task gets switched in and out. See
* demo/common/minimal/integer.c for more information.
* The second and third tasks pass an incrementing value between each other on
* a message queue. See demo/common/minimal/PollQ.c for more information.
* Main1.c also creates a check task. This periodically checks that all the
* other tasks are still running and have not experienced any unexpected
* results. If all the other tasks are executing correctly an LED is flashed
* once every mainCHECK_PERIOD milliseconds. If any of the tasks have not
* executed, or report and error, the frequency of the LED flash will increase
* On entry to main an 'X' is transmitted. Monitoring the serial port using a
* dumb terminal allows for verification that the device is not continuously
* being reset (no more than one 'X' should be transmitted).
* contains important information on the use of the
* PIC18F port.
Changes from V2.0.0
+ Delay periods are now specified using variables and constants of
portTickType rather than unsigned long.
/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
/* Demo app include files. */
#include "PollQ.h"
#include "integer.h"
#include "partest.h"
#include "serial.h"
/* The period between executions of the check task before and after an error
has been discovered. If an error has been discovered the check task runs
more frequently - increasing the LED flash rate. */
#define mainNO_ERROR_CHECK_PERIOD ( ( portTickType ) 1000 / portTICK_RATE_MS )
#define mainERROR_CHECK_PERIOD ( ( portTickType ) 100 / portTICK_RATE_MS )
/* Priority definitions for some of the tasks. Other tasks just use the idle
priority. */
/* The LED that is flashed by the check task. */
#define mainCHECK_TASK_LED ( 0 )
/* Constants required for the communications. Only one character is ever
transmitted. */
#define mainCOMMS_QUEUE_LENGTH ( 5 )
#define mainNO_BLOCK ( ( portTickType ) 0 )
#define mainBAUD_RATE ( ( unsigned long ) 9600 )
* The task function for the "Check" task.
static void vErrorChecks( void *pvParameters );
* Checks the unique counts of other tasks to ensure they are still operational.
* Returns pdTRUE if an error is detected, otherwise pdFALSE.
static portBASE_TYPE prvCheckOtherTasksAreStillRunning( void );
/* Creates the tasks, then starts the scheduler. */
void main( void )
/* Initialise the required hardware. */
/* Send a character so we have some visible feedback of a reset. */
xSerialPortInitMinimal( mainBAUD_RATE, mainCOMMS_QUEUE_LENGTH );
xSerialPutChar( NULL, 'X', mainNO_BLOCK );
/* Start the standard demo tasks found in the demo\common directory. */
vStartIntegerMathTasks( tskIDLE_PRIORITY );
vStartPolledQueueTasks( mainQUEUE_POLL_PRIORITY );
/* Start the check task defined in this file. */
xTaskCreate( vErrorChecks, ( const char * const ) "Check", configMINIMAL_STACK_SIZE, NULL, mainCHECK_TASK_PRIORITY, NULL );
/* Start the scheduler. Will never return here. */
static void vErrorChecks( void *pvParameters )
portTickType xDelayTime = mainNO_ERROR_CHECK_PERIOD;
portBASE_TYPE xErrorOccurred;
/* Cycle for ever, delaying then checking all the other tasks are still
operating without error. */
for( ;; )
/* Wait until it is time to check the other tasks. */
vTaskDelay( xDelayTime );
/* Check all the other tasks are running, and running without ever
having an error. */
xErrorOccurred = prvCheckOtherTasksAreStillRunning();
/* If an error was detected increase the frequency of the LED flash. */
if( xErrorOccurred == pdTRUE )
xDelayTime = mainERROR_CHECK_PERIOD;
/* Flash the LED for visual feedback. */
vParTestToggleLED( mainCHECK_TASK_LED );
static portBASE_TYPE prvCheckOtherTasksAreStillRunning( void )
portBASE_TYPE xErrorHasOccurred = pdFALSE;
if( xAreIntegerMathsTaskStillRunning() != pdTRUE )
xErrorHasOccurred = pdTRUE;
if( xArePollingQueuesStillRunning() != pdTRUE )
xErrorHasOccurred = pdTRUE;
return xErrorHasOccurred;