FreeRTOS-Kernel/Demo/PIC18_MPLAB/main1.c

/*
    FreeRTOS V6.1.1 - Copyright (C) 2011 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 exception to the GPL is included to allow you to distribute
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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 
 * to mainERROR_FLASH_RATE.
 *
 * 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).
 *
 * http://www.FreeRTOS.org 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. */
#define mainQUEUE_POLL_PRIORITY			( tskIDLE_PRIORITY + 2 )
#define mainCHECK_TASK_PRIORITY			( tskIDLE_PRIORITY + 3 )

/* 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. */
	vParTestInitialise();
	vPortInitialiseBlocks();

	/* 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. */
	vTaskStartScheduler();
}
/*-----------------------------------------------------------*/

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;
}
/*-----------------------------------------------------------*/