FreeRTOS/Demo/WIN32-MSVC/main_blinky.c

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    ***************************************************************************
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    ***************************************************************************

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*/

/******************************************************************************
 * NOTE 1: Do not expect to get real time behaviour from the Win32 port or this
 * demo application.  It is provided as a convenient development and
 * demonstration test bed only.  Windows will not be running the FreeRTOS
 * threads continuously, so the timing information in the FreeRTOS+Trace logs
 * have no meaningful units.  See the documentation page for the Windows
 * simulator for further explanation:
 * http://www.freertos.org/FreeRTOS-Windows-Simulator-Emulator-for-Visual-Studio-and-Eclipse-MingW.html
 * - READ THE WEB DOCUMENTATION FOR THIS PORT FOR MORE INFORMATION ON USING IT -
 *
 * NOTE 2:  This project provides two demo applications.  A simple blinky style
 * project, and a more comprehensive test and demo application.  The
 * mainCREATE_SIMPLE_BLINKY_DEMO_ONLY setting in main.c is used to select
 * between the two.  See the notes on using mainCREATE_SIMPLE_BLINKY_DEMO_ONLY
 * in main.c.  This file implements the simply blinky style version.
 *
 * NOTE 3:  This file only contains the source code that is specific to the
 * basic demo.  Generic functions, such FreeRTOS hook functions, are defined
 * in main.c.
 ******************************************************************************
 *
 * main_blinky() creates one queue, one software timer, and two tasks.  It then
 * starts the scheduler.
 *
 * The Queue Send Task:
 * The queue send task is implemented by the prvQueueSendTask() function in
 * this file.  It uses vTaskDelayUntil() to create a period task that sends the
 * value 100 to the queue every 200 milliseconds (please read the notes above
 * regarding the accuracy of timing under Windows).
 *
 * The Queue Send Software Timer:
 * The timer is a one-shot timer that is reset by a key press.  The timer's
 * period is set to two seconds - if the timer expires then its callback
 * function writes the value 200 to the queue.  The callback function is
 * implemented by prvQueueSendTimerCallback() within this file.
 *
 * The Queue Receive Task:
 * The queue receive task is implemented by the prvQueueReceiveTask() function
 * in this file.  prvQueueReceiveTask() waits for data to arrive on the queue.
 * When data is received, the task checks the value of the data, then outputs a
 * message to indicate if the data came from the queue send task or the queue
 * send software timer.  As the queue send task writes to the queue every 200ms,
 * the queue receive task will print a message indicating that it received data
 * from the queue send task every 200ms.  The queue receive task will print a
 * message indicating that it received data from the queue send software timer
 * 2 seconds after a key was last pressed.
 */

/* Standard includes. */
#include <stdio.h>
#include <conio.h>

/* Kernel includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "timers.h"
#include "semphr.h"

/* Priorities at which the tasks are created. */
#define mainQUEUE_RECEIVE_TASK_PRIORITY		( tskIDLE_PRIORITY + 2 )
#define	mainQUEUE_SEND_TASK_PRIORITY		( tskIDLE_PRIORITY + 1 )

/* The rate at which data is sent to the queue.  The times are converted from
milliseconds to ticks by the pdMS_TO_TICKS() macro where they are used. */
#define mainTASK_SEND_FREQUENCY_MS			200
#define mainTIMER_SEND_FREQUENCY_MS			2000

/* The number of items the queue can hold. */
#define mainQUEUE_LENGTH					( 2 )

/* Values passed to the two tasks just to check the task parameter
functionality. */
#define mainQUEUE_SEND_PARAMETER			( 0x1111UL )
#define mainQUEUE_RECEIVE_PARAMETER			( 0x22UL )

/* The values sent to the queue receive task from the queue send task and the
queue send software timer respectively. */
#define mainVALUE_SENT_FROM_TASK			( 100UL )
#define mainVALUE_SENT_FROM_TIMER			( 200UL )

/*-----------------------------------------------------------*/

/*
 * The tasks as described in the comments at the top of this file.
 */
static void prvQueueReceiveTask( void *pvParameters );
static void prvQueueSendTask( void *pvParameters );

/*
 * The callback function executed when the software timer expires.
 */
static void prvQueueSendTimerCallback( TimerHandle_t xTimerHandle );

/*-----------------------------------------------------------*/

/* The queue used by both tasks. */
static QueueHandle_t xQueue = NULL;

/* A software timer that is started from the tick hook. */
static TimerHandle_t xTimer = NULL;

/*-----------------------------------------------------------*/

void main_blinky( void )
{
const TickType_t xTimerPeriod = pdMS_TO_TICKS( mainTIMER_SEND_FREQUENCY_MS );

	/* Create the queue. */
	xQueue = xQueueCreate( mainQUEUE_LENGTH, sizeof( unsigned long ) );

	if( xQueue != NULL )
	{
		/* Start the two tasks as described in the comments at the top of this
		file. */
		xTaskCreate( prvQueueReceiveTask,					/* The function that implements the task. */
					"Rx", 									/* The text name assigned to the task - for debug only as it is not used by the kernel. */
					configMINIMAL_STACK_SIZE, 				/* The size of the stack to allocate to the task. */
					( void * ) mainQUEUE_RECEIVE_PARAMETER, /* The parameter passed to the task - just to check the functionality. */
					mainQUEUE_RECEIVE_TASK_PRIORITY, 		/* The priority assigned to the task. */
					NULL );									/* The task handle is not required, so NULL is passed. */

		xTaskCreate( prvQueueSendTask, "TX", configMINIMAL_STACK_SIZE, ( void * ) mainQUEUE_SEND_PARAMETER, mainQUEUE_SEND_TASK_PRIORITY, NULL );

		/* Create the software timer, but don't start it yet. */
		xTimer = xTimerCreate( "Timer",				/* The text name assigned to the software timer - for debug only as it is not used by the kernel. */
								xTimerPeriod,		/* The period of the software timer in ticks. */
								pdFALSE,			/* xAutoReload is set to pdFALSE, so this is a one shot timer. */
								NULL,				/* The timer's ID is not used. */
								prvQueueSendTimerCallback );/* The function executed when the timer expires. */

		/* Start the tasks and timer running. */
		vTaskStartScheduler();
	}

	/* If all is well, the scheduler will now be running, and the following
	line will never be reached.  If the following line does execute, then
	there was insufficient FreeRTOS heap memory available for the idle and/or
	timer tasks	to be created.  See the memory management section on the
	FreeRTOS web site for more details. */
	for( ;; );
}
/*-----------------------------------------------------------*/

static void prvQueueSendTask( void *pvParameters )
{
TickType_t xNextWakeTime;
const TickType_t xBlockTime = pdMS_TO_TICKS( mainTASK_SEND_FREQUENCY_MS );
const uint32_t ulValueToSend = mainVALUE_SENT_FROM_TASK;

	/* Remove compiler warning in the case that configASSERT() is not
	defined. */
	( void ) pvParameters;

	/* Check the task parameter is as expected. */
	configASSERT( ( ( unsigned long ) pvParameters ) == mainQUEUE_SEND_PARAMETER );

	/* Initialise xNextWakeTime - this only needs to be done once. */
	xNextWakeTime = xTaskGetTickCount();

	for( ;; )
	{
		/* Place this task in the blocked state until it is time to run again.
		The block time is specified in ticks, the constant used converts ticks
		to ms.  While in the Blocked state this task will not consume any CPU
		time. */
		vTaskDelayUntil( &xNextWakeTime, xBlockTime );

		/* Send to the queue - causing the queue receive task to unblock and
		toggle the LED.  0 is used as the block time so the sending operation
		will not block - it shouldn't need to block as the queue should always
		have at least one space at this point in the code. */
		xQueueSend( xQueue, &ulValueToSend, 0U );
	}
}
/*-----------------------------------------------------------*/

static void prvQueueSendTimerCallback( TimerHandle_t xTimerHandle )
{
const uint32_t ulValueToSend = mainVALUE_SENT_FROM_TIMER;

	/* Avoid compiler warnings resulting from the unused parameter. */
	( void ) xTimerHandle;

	/* Send to the queue - causing the queue receive task to unblock and
	write out a message.  This function is called from the timer/daemon task, so
	must not block.  Hence the block time is set to 0. */
	xQueueSend( xQueue, &ulValueToSend, 0U );
}
/*-----------------------------------------------------------*/

static void prvQueueReceiveTask( void *pvParameters )
{
unsigned long ulReceivedValue;

	/* Remove compiler warning in the case that configASSERT() is not
	defined. */
	( void ) pvParameters;

	/* Check the task parameter is as expected. */
	configASSERT( ( ( unsigned long ) pvParameters ) == mainQUEUE_RECEIVE_PARAMETER );

	for( ;; )
	{
		/* Wait until something arrives in the queue - this task will block
		indefinitely provided INCLUDE_vTaskSuspend is set to 1 in
		FreeRTOSConfig.h. */
		xQueueReceive( xQueue, &ulReceivedValue, portMAX_DELAY );

		/*  To get here something must have been received from the queue, but
		is it the expected value?  Normally calling printf() from a task is not
		a good idea.  Here there is lots of stack space and only one task is
		using console IO so it is ok. */
		if( ulReceivedValue == mainVALUE_SENT_FROM_TASK )
		{
			printf( "Message received from task\r\n" );
		}
		else if( ulReceivedValue == mainVALUE_SENT_FROM_TIMER )
		{
			printf( "Message received from software timer\r\n" );
		}
		else
		{
			printf( "Unexpected message\r\n" );
		}

		/* Reset the timer if a key has been pressed.  The timer will write
		mainVALUE_SENT_FROM_TIMER to the queue when it expires. */
		if( _kbhit() != 0 )
		{
			/* Remove the key from the input buffer. */
			( void ) _getch();

			/* Reset the software timer. */
			xTimerReset( xTimer, portMAX_DELAY );
		}
	}
}
/*-----------------------------------------------------------*/