FreeRTOS-Kernel/FreeRTOS/Demo/Common/Minimal/flash.c

/*
 * FreeRTOS V202112.00
 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://aws.amazon.com/freertos
 *
 */

/**
 * 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    ( ( TickType_t ) 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 UBaseType_t uxFlashTaskNumber = 0;

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

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

void vStartLEDFlashTasks( UBaseType_t uxPriority )
{
    BaseType_t xLEDTask;

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

static portTASK_FUNCTION( vLEDFlashTask, pvParameters )
{
    TickType_t xFlashRate, xLastFlashTime;
    UBaseType_t 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 * ( TickType_t ) uxLED );
    xFlashRate /= portTICK_PERIOD_MS;

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