View source for Deleting a Task ← Deleting a Task

[[category: Free RTOS with Arduino]]
In earlier tutorials, we saw how to create tasks and used.<br>
In this tutorial, we will see how to delete a task once its job is done.<br><br>
 

=API Details=
Here we will discuss some of the most frequently used APIs related to tasks.

<b>1.xTaskCreate()</b>: This interface is used to create a new Task, if the task is successfully created then it returns pdPass(1) or else errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY(-1). Check [http://www.freertos.org/a00125.html this link] for more details.<br>

<b>2.vTaskDelay()</b>: This function is used to delay/block the task for specified delay time(ticks). INCLUDE_vTaskDelay needs to be set to 1 in FreeRtosConfig.h file for using this function. Check [http://www.freertos.org/a00127.html this link] for more details.<br>

<b>3.vTaskDelete():</b>This function is used to delete as task. We need to pass the taskHandle of the task to be deleted.<br> To delete the own task we should pass NULL as parameter.<br> 
Please check [http://www.freertos.org/a00126.html this link] for details. <br><br>

=Example=
In this example, we are going to create 3-Tasks with different priorities.<br>
Each task will run for some time and then goes to blocked state allowing the other tasks to run. Once the Task completes its job, it will delete itself. 
<html> <script src="https://gist.github.com/SaheblalBagwan/36e4817cd307be96ddb7dfb9378443ba.js"></script> </html>
<br><br>

=Output=
[[FILE:TaskDeleteUsage.jpg]]
<br>
0. Serial port is initialized and 3-Tasks are created with different priorities. Setup message is printed.
#Cpu chooses Task3 out of the 4-Tasks(1,2,3,and idle) as it has higher priority. Task3 will run for some time and goes to wait/blocked state for 150ms.
#At this 3-Tasks(1,2,idle) are available and scheduler chooses Task2. It runs for some time and goes to blocked state for 150ms.
#Now 2-Tasks(1,Idle) are available and Task1 runs because of its higher priority. It also goes to blocked state for 100ms
#Now scheduler is left out with Idle task and it keeps running till one of the tasks waiting time is elapsed and comes out of blocked state.
#Since Task1 was blocked for only 100ms, it will come out of the blocked state and starts running. And finally it deletes itself once it job is done.
#Now again Idle task will start running as there are no other tasks to run.
#At this point Task3 will come out of the waiting/blocked state and preempts the Idle task and starts running. It also deletes itself.
#By this time Task2 is also out of blocked state and runs for some time and deletes itself.
#Now there is only one task ie.The idle task as keeps running.