FreeRTOS-Kernel/FreeRTOS/Demo/PIC32MX_MPLAB/main_blinky.c

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/******************************************************************************
 * NOTE 1:  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 2:  This file only contains the source code that is specific to the
 * basic demo.  Generic functions, such FreeRTOS hook functions, and functions
 * required to configure the hardware, are defined in main.c.
 ******************************************************************************
 *
 * main_blinky() creates one queue, two tasks, and one software timer.  It then 
 * starts the scheduler.
 *
 * The Blinky Software Timer:
 * This demonstrates an auto-reload software timer.  The timer callback function
 * does nothing but toggle an LED.
 *
 * The Queue Send Task:
 * The queue send task is implemented by the prvQueueSendTask() function in
 * this file.  prvQueueSendTask() sits in a loop that causes it to repeatedly
 * block for 200 milliseconds, before sending the value 100 to the queue that
 * was created within main_blinky().  Once the value is sent, the task loops
 * back around to block for another 200 milliseconds.
 *
 * The Queue Receive Task:
 * The queue receive task is implemented by the prvQueueReceiveTask() function
 * in this file.  prvQueueReceiveTask() sits in a loop where it repeatedly
 * blocks on attempts to read data from the queue that was created within
 * main_blinky().  When data is received, the task checks the value of the
 * data, and if the value equals the expected 100, toggles the LED.  The 'block
 * time' parameter passed to the queue receive function specifies that the
 * task should be held in the Blocked state indefinitely to wait for data to
 * be available on the queue.  The queue receive task will only leave the
 * Blocked state when the queue send task writes to the queue.  As the queue
 * send task writes to the queue every 200 milliseconds, the queue receive
 * task leaves the Blocked state every 200 milliseconds, and therefore toggles
 * the LED every 200 milliseconds.
 */

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

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

/* Standard demo includes. */
#include "partest.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 200ms value is converted
to ticks using the portTICK_RATE_MS constant. */
#define mainQUEUE_SEND_FREQUENCY_MS			( 200 / portTICK_RATE_MS )

/* The number of items the queue can hold.  This is 1 as the receive task
will remove items as they are added, meaning the send task should always find
the queue empty. */
#define mainQUEUE_LENGTH					( 1 )

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

/* The period of the blinky software timer.  The period is specified in ms and
converted to ticks using the portTICK_RATE_MS constant. */
#define mainBLINKY_TIMER_PERIOD				( 50 / portTICK_RATE_MS )

/* The LED used by the communicating tasks and the blinky timer respectively. */
#define mainTASKS_LED						( 0 )
#define mainTIMER_LED						( 1 )

/* Misc. */
#define mainDONT_BLOCK						( 0 )

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

/*
 * 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 for the blinky software timer, as described at the top
 * of this file.
 */
static void prvBlinkyTimerCallback( xTimerHandle xTimer );
 
/*
 * Called by main() to create the simply blinky style application if
 * mainCREATE_SIMPLE_BLINKY_DEMO_ONLY is set to 1.
 */
void main_blinky( void );

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

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

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

void main_blinky( void )
{
xTimerHandle xTimer;

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

	if( xQueue != NULL )
	{
		/* Create the two tasks as described in the comments at the top of this
		file. */
		xTaskCreate( prvQueueReceiveTask,					/* The function that implements the task. */
					( signed char * ) "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, ( signed char * ) "TX", configMINIMAL_STACK_SIZE, ( void * ) mainQUEUE_SEND_PARAMETER, mainQUEUE_SEND_TASK_PRIORITY, NULL );

		/* Create the blinky software timer as described at the top of this
		file. */
		xTimer = xTimerCreate( 	( const signed char * ) "Blinky",	/* A text name, purely to help debugging. */
								( mainBLINKY_TIMER_PERIOD ),		/* The timer period. */
								pdTRUE,								/* This is an auto-reload timer, so xAutoReload is set to pdTRUE. */
								( void * ) 0,						/* The ID is not used, so can be set to anything. */
								prvBlinkyTimerCallback				/* The callback function that inspects the status of all the other tasks. */
							);	
		
		if( xTimer != NULL )
		{
			xTimerStart( xTimer, mainDONT_BLOCK );
		}
				
		/* 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 )
{
portTickType xNextWakeTime;
const unsigned long ulValueToSend = 100UL;

	/* 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, mainQUEUE_SEND_FREQUENCY_MS );

		/* 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
		be empty at this point in the code. */
		xQueueSend( xQueue, &ulValueToSend, 0U );
	}
}
/*-----------------------------------------------------------*/

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

	/* 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?  If it is, toggle the LED. */
		if( ulReceivedValue == 100UL )
		{
			vParTestToggleLED( mainTASKS_LED );
			ulReceivedValue = 0U;
		}
	}
}
/*-----------------------------------------------------------*/

static void prvBlinkyTimerCallback( xTimerHandle xTimer )
{
	/* This function is called when the blinky software time expires.  All the
	function does is toggle the LED.  LED mainTIMER_LED should therefore toggle
	with the period set by mainBLINKY_TIMER_PERIOD. */
	vParTestToggleLED( mainTIMER_LED );
}