gyro_board/src/usb/CommonDemoTasks/flash.c

/*
    FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.

    ***************************************************************************
    *                                                                         *
    * If you are:                                                             *
    *                                                                         *
    *    + New to FreeRTOS,                                                   *
    *    + Wanting to learn FreeRTOS or multitasking in general quickly       *
    *    + Looking for basic training,                                        *
    *    + Wanting to improve your FreeRTOS skills and productivity           *
    *                                                                         *
    * then take a look at the FreeRTOS eBook                                  *
    *                                                                         *
    *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *
    *                  http://www.FreeRTOS.org/Documentation                  *
    *                                                                         *
    * A pdf reference manual is also available.  Both are usually delivered   *
    * to your inbox within 20 minutes to two hours when purchased between 8am *
    * and 8pm GMT (although please allow up to 24 hours in case of            *
    * exceptional circumstances).  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 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.
    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 Richard Barry, contact details for whom are available on the
    FreeRTOS WEB site.

    1 tab == 4 spaces!

    http://www.FreeRTOS.org - Documentation, latest information, license and
    contact details.

    http://www.SafeRTOS.com - A version that is certified for use in safety
    critical systems.

    http://www.OpenRTOS.com - Commercial support, development, porting,
    licensing and training services.
*/

/**
 * 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);

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

// To continually print out the serial output, run the following command.
// while true; do [ `ls /dev/ttyACM* 2>/dev/null` ] && ls /dev/ttyACM* | python -c "import sys; x = sys.stdin.readline()[:-1].split(' ')[0]; sys.stderr.write('Connecting to %s\n' % (x,)); print x" | xargs cat || sleep 0.25;  done

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. */