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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.
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* *
* Looking for a quick start? Then check out the FreeRTOS eBook! *
* See for details *
* *
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* 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 portLONG.
/* 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 portLONG ) 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 portCHAR * 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;