FreeRTOS/Demo/Common/Minimal/flash.c

/*
    FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.

    FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME.  PLEASE VISIT
    http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

    ***************************************************************************
     *                                                                       *
     *    FreeRTOS tutorial books are available in pdf and paperback.        *
     *    Complete, revised, and edited pdf reference manuals are also       *
     *    available.                                                         *
     *                                                                       *
     *    Purchasing FreeRTOS documentation will not only help you, by       *
     *    ensuring you get running as quickly as possible and with an        *
     *    in-depth knowledge of how to use FreeRTOS, it will also help       *
     *    the FreeRTOS project to continue with its mission of providing     *
     *    professional grade, cross platform, de facto standard solutions    *
     *    for microcontrollers - completely free of charge!                  *
     *                                                                       *
     *    >>> See http://www.FreeRTOS.org/Documentation for details. <<<     *
     *                                                                       *
     *    Thank you for using FreeRTOS, and thank you for your support!      *
     *                                                                       *
    ***************************************************************************


    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
    kernel.

    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: http://www.freertos.org/a00114.html and also obtained by
    writing to Real Time Engineers Ltd., contact details for whom are available
    on the FreeRTOS WEB site.

    1 tab == 4 spaces!

    ***************************************************************************
     *                                                                       *
     *    Having a problem?  Start by reading the FAQ "My application does   *
     *    not run, what could be wrong?"                                     *
     *                                                                       *
     *    http://www.FreeRTOS.org/FAQHelp.html                               *
     *                                                                       *
    ***************************************************************************


    http://www.FreeRTOS.org - Documentation, books, training, latest versions, 
    license and Real Time Engineers Ltd. contact details.

    http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
    including FreeRTOS+Trace - an indispensable productivity tool, and our new
    fully thread aware and reentrant UDP/IP stack.

    http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High 
    Integrity Systems, who sell the code with commercial support, 
    indemnification and middleware, under the OpenRTOS brand.
    
    http://www.SafeRTOS.com - 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.
*/

/**
 * This version of flash .c is for use on systems that have limited stack space
 * and no display facilities.  The complete version can be found in the 
 * Demo/Common/Full directory.
 * 
 * Three tasks are created, each of which flash an LED at a different rate.  The first 
 * LED flashes every 200ms, the second every 400ms, the third every 600ms.
 *
 * The LED flash tasks provide instant visual feedback.  They show that the scheduler 
 * is still operational.
 *
 */


#include <stdlib.h>

/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"

/* Demo program include files. */
#include "partest.h"
#include "flash.h"

#define ledSTACK_SIZE		configMINIMAL_STACK_SIZE
#define ledNUMBER_OF_LEDS	( 3 )
#define ledFLASH_RATE_BASE	( ( portTickType ) 333 )

/* Variable used by the created tasks to calculate the LED number to use, and
the rate at which they should flash the LED. */
static volatile unsigned portBASE_TYPE uxFlashTaskNumber = 0;

/* The task that is created three times. */
static portTASK_FUNCTION_PROTO( vLEDFlashTask, pvParameters );

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

void vStartLEDFlashTasks( unsigned portBASE_TYPE uxPriority )
{
signed portBASE_TYPE xLEDTask;

	/* Create the three tasks. */
	for( xLEDTask = 0; xLEDTask < ledNUMBER_OF_LEDS; ++xLEDTask )
	{
		/* Spawn the task. */
		xTaskCreate( vLEDFlashTask, ( signed char * ) "LEDx", ledSTACK_SIZE, NULL, uxPriority, ( xTaskHandle * ) NULL );
	}
}
/*-----------------------------------------------------------*/

static portTASK_FUNCTION( vLEDFlashTask, pvParameters )
{
portTickType xFlashRate, xLastFlashTime;
unsigned portBASE_TYPE uxLED;

	/* The parameters are not used. */
	( void ) pvParameters;

	/* Calculate the LED and flash rate. */
	portENTER_CRITICAL();
	{
		/* See which of the eight LED's we should use. */
		uxLED = uxFlashTaskNumber;

		/* Update so the next task uses the next LED. */
		uxFlashTaskNumber++;
	}
	portEXIT_CRITICAL();

	xFlashRate = ledFLASH_RATE_BASE + ( ledFLASH_RATE_BASE * ( portTickType ) uxLED );
	xFlashRate /= portTICK_RATE_MS;

	/* We will turn the LED on and off again in the delay period, so each
	delay is only half the total period. */
	xFlashRate /= ( portTickType ) 2;

	/* We need to initialise xLastFlashTime prior to the first call to 
	vTaskDelayUntil(). */
	xLastFlashTime = xTaskGetTickCount();

	for(;;)
	{
		/* Delay for half the flash period then turn the LED on. */
		vTaskDelayUntil( &xLastFlashTime, xFlashRate );
		vParTestToggleLED( uxLED );

		/* Delay for half the flash period then turn the LED off. */
		vTaskDelayUntil( &xLastFlashTime, xFlashRate );
		vParTestToggleLED( uxLED );
	}
} /*lint !e715 !e818 !e830 Function definition must be standard for task creation. */