3. Use of vTaskDelete()

Amruta (talk) 18:55, 14 April 2015 (IST)

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1 Intro
2 Code
3 Output
- 3.1 Waveform

Intro

vTaskDelete() API removes the task from the RTOS real time kernels management. In this tutorial we will see how to use it and also its effect on task scheduling. You can go through the details of vTaskDelete() and basics of task here.

Code

	/***************************************************************************************************
	ExploreEmbedded
	****************************************************************************************************
	* File: main.c (FreeRTOS)
	* Version: 15.0
	* Author: ExploreEmbedded
	* Website: http://www.exploreembedded.com/wiki
	* Description: Program to demonstrate the effect of vTaskDelay on the tasks

	The libraries have been tested on ExploreEmbedded development boards. We strongly believe that the
	library works on any of development boards for respective controllers. However, ExploreEmbedded
	disclaims any kind of hardware failure resulting out of usage of libraries, directly or indirectly.
	Files may be subject to change without prior notice. The revision history contains the information
	related to updates.


	GNU GENERAL PUBLIC LICENSE:
	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program 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
	along with this program. If not, see <http://www.gnu.org/licenses/>.

	Errors and omissions should be reported to codelibraries@exploreembedded.com
	**************************************************************************************************/

	/* Scheduler include files. */
	#include "FreeRtOSConfig.h"
	#include "FreeRTOS.h"
	#include "task.h"
	#include "croutine.h"
	#include "uart.h" // Explore Embedded UART library

	xTaskHandle TaskHandle_1;
	xTaskHandle TaskHandle_2;
	xTaskHandle TaskHandle_3;

	/* Local Tasks declaration */
	static void MyTask1(void* pvParameters);
	static void MyTask2(void* pvParameters);
	static void MyTask3(void* pvParameters);
	static void MyIdleTask(void* pvParameters);

	#define LED_IdleTask 0x01u
	#define LED_Task1 0x02u
	#define LED_Task2 0x04u
	#define LED_Task3 0x08u
	#define LED_Task4 0x10u

	#define LED_PORT LPC_GPIO2->FIOPIN
	int main(void)
	{

	SystemInit(); /* Initialize the controller */
	UART_Init(38400); /* Initialize the Uart module */
	LPC_GPIO2->FIODIR = 0xffffffffu;

	/* Create the three tasks with priorities 1,2,3. Only tasks will be created.
	* Tasks will be excecuted once the scheduler is started.
	* An idle task is also created, which will be run when there are no tasks in RUN state */
	xTaskCreate( MyTask1, ( signed char * )"Task1", configMINIMAL_STACK_SIZE, NULL, 1, &TaskHandle_1 );
	xTaskCreate( MyTask2, ( signed char * )"Task2", configMINIMAL_STACK_SIZE, NULL, 2, &TaskHandle_2 );
	xTaskCreate( MyTask3, ( signed char * )"Task3", configMINIMAL_STACK_SIZE, NULL, 3, &TaskHandle_3 );
	xTaskCreate( MyIdleTask, ( signed char * )"IdleTask", configMINIMAL_STACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );

	UART_Printf("\n\rIn the main");

	vTaskStartScheduler(); /* Start the schedular */

	while(1);
	}


	static void MyTask1(void* pvParameters)
	{
	LED_PORT = LED_Task1; /* Led to indicate the execution of Task1*/
	UART_Printf("\n\rTask1, waiting for some time");
	vTaskDelay(200);

	LED_PORT = LED_Task1; /* Led to indicate the execution of Task1*/
	UART_Printf("\n\rBack in Task1");

	vTaskDelete(TaskHandle_1);
	}


	static void MyTask2(void* pvParameters)
	{
	LED_PORT = LED_Task2; /* Led to indicate the execution of Task2*/
	UART_Printf("\n\rTask2, waiting for some time");
	vTaskDelay(200);

	LED_PORT = LED_Task2; /* Led to indicate the execution of Task2*/
	UART_Printf("\n\rBack in Task2");

	vTaskDelete(TaskHandle_2);
	}


	static void MyTask3(void* pvParameters)
	{

	LED_PORT = LED_Task3; /* Led to indicate the execution of Task3*/
	UART_Printf("\n\rTask3, waiting for some time");
	vTaskDelay(200);

	LED_PORT = LED_Task3; /* Led to indicate the execution of Task3*/
	UART_Printf("\n\rBack in Task3");

	vTaskDelete(TaskHandle_3);
	}


	static void MyIdleTask(void* pvParameters)
	{
	while(1)
	{
	LED_PORT = LED_IdleTask; /* Led to indicate the execution of Idle Task*/
	UART_Printf("\n\rIn idle state");
	}
	}