Latest revision as of 17:54, 14 July 2016

In earlier tutorials, we saw how to create, delete, suspend and resume the tasks.
In this tutorial, we will see how to read the Task info(state, Stack size, priority.

API Details

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

xTaskCreate(): 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 this link for more details.

vTaskDelay(): 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 this link for more details.

vTaskSuspend(): This function is used to Suspend a task, the suspended remains in the same state util it is resumed.
For this, we need to pass the handle of the tasks that needs to be suspended. Passing NULL will suspend own task. Check this link for more details.

vTaskResume(): This function is used to resume a suspended task. If the Resumed task has higher priority than the running task then it will preempt the running task or else stays in ready state
For this, we need to pass the handle of the task to be resumed. Check this link for more details.

vTaskList(): This function is used to read the task details(name, state, priority, num). We need to pass a string pointer(buffer) to which it copies the above task details. The buffer size should be minimum 40 bytes per task. Check this link for more details.

Example1

In this example, we will be creating 3-tasks which run for some time and enter the blocked state allowing other tasks to run. We will include INT0 falling edge interrupt to read and display the current task list with all the task info. Every time interrupt is generated it will take the snapshot of tasks(name, state, priority, num) and sends on Serial port.

Output1

All the tasks will be running for some time and enter the blocked state allowing other tasks to run. Task3 suspends and resumes the Task1 alternatively. Whenever INT0 interrupt is generated, ISR will take the snapshot of all the task and sends it on the serial port.

Downloads

Download the complete project and libraries from here.

Have an opinion, suggestion , question or feedback about the article let it out here!

@@ Line 1: / Line 1: @@
 [[category: Free RTOS with Arduino]]
-In this tutorial, we will be discussing a Semaphore and its types ie. Binary, Mutex, Counting.<br>
+In earlier tutorials, we saw how to create, delete, suspend and resume the tasks.<br>
-Later we will see each semaphore in detail with its pros and cons.
+In this tutorial, we will see how to read the Task info(state, Stack size, priority.<br>
-Also, we will be looking into priority inversion and priority inheritance.<br><br>
-=What is a Semaphore?=
+[[File:0ReadTaskInfo.png]]
-Semaphore is a technique for synchronizing two/more task competing for the same resources. When a task wants to use a resource, it requests for the semaphore and will be allocated if the semaphore is available. If the semaphore is not available then the requesting task will go to blocked state till the semaphore becomes free.<br><br>
-=Types of Semaphores=
+=API Details=
-There are 3-types of semaphores namely Binary, Counting and Mutex semaphore.
+Here we will discuss some of the most frequently used APIs related to tasks.
-*<b>Binary Semaphore</b>:
-*<b>Counnting Semaphore</b>:
+<b>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>Mutex Semaphore</b>:
+<b>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>vTaskSuspend():</b> This function is used to Suspend a task, the suspended remains in the same state util it is resumed.<br>
+For this, we need to pass the handle of the tasks that needs to be suspended. Passing NULL will suspend own task. Check [http://www.freertos.org/a00130.html this link] for more details.
+<b>vTaskResume():</b> This function is used to resume a suspended task. If the Resumed task has higher priority than the running task then it will preempt the running task or else stays in ready state<br>
+For this, we need to pass the handle of the task to be resumed. Check [http://www.freertos.org/a00131.html this link] for more details.
+<b>vTaskList():</b> This function is used to read the task details(name, state, priority, num). We need to pass a string pointer(buffer) to which it copies the above task details. The buffer size should be minimum 40 bytes per task. Check [http://www.freertos.org/a00021.html#vTaskList this link] for more details.
+<br><br>
+=Example1=
+In this example, we will be creating 3-tasks which run for some time and enter the blocked state allowing other tasks to run. We will include INT0 falling edge interrupt to read and display the current task list with all the task info. Every time interrupt is generated it will take the snapshot of tasks(name, state, priority, num) and sends on Serial port.
+<html><script src="https://gist.github.com/SaheblalBagwan/c696f165daba3e2826cd3b9ebf33785f.js"></script></html>
+=Output1=
+[[FILE:VTaskList().png]]
+<br>
+All the tasks will be running for some time and enter the blocked state allowing other tasks to run. Task3 suspends and resumes the Task1 alternatively.
+Whenever INT0 interrupt is generated, ISR will take the snapshot of all the task and sends it on the serial port.
+=Downloads=
+Download the complete project and libraries from [https://github.com/ExploreEmbedded/Arduino_FreeRTOS/archive/master.zip here].<br><br>
+Have an opinion, suggestion , question or feedback about the article let it out here!
+{{DISQUS}}

Difference between revisions of "Read Task Info : vTaskList()"

Latest revision as of 17:54, 14 July 2016

Contents

API Details

Example1

Output1

Downloads