6 Task Notifications

Question 1

Give three examples of communication objects?

Answer 1

Queues, Semaphores, and event groups.

Question 2

How do task notifications compare to semaphores?

Answer 2

Task notifications are smaller and faster than semaphores.

Question 3

What is the difference between a pending and not pending, notification state?

Answer 3

Pending: A task has received a task notification value.
Not Pending: after task has read the task notification value.

Question 4

What are the benefits and limitations to task notifications?

Answer 4

Benefits:
1. Faster than queues, semaphores and event groups
by up to 45%.
2. Less memory than queue, semaphore, or event
group.

Limitations:
1. Cannot send data or event to interrupt handler.
2. Cannot notify to multiple tasks.
3. Can only send one data item (32-bit notification
value)

Question 5

What state is the notification state on creation of a task?

Answer 5

On creation of a task the notification state is not pending.

Question 6

What API Options are there to notify a task?

Answer 6

xTaskNotifyGive() and xTaskNotify().

Question 7

Compare xTaskNotifyGive() and xTaskNotify().

Answer 7

xTaskNotifyGive(): used as an alternative to binary or
counting semaphore. Used to increament task
notification value (TNV).

xTaskNofity(): More flexible than xTaskNotifyGive(). Can
increment, give a new value to the task notification
value, or set a number of bits in the value.
Can be used in place of an event group.

Question 8

What api options is there to take a notifications?

Answer 8

ulTaskNotifyTake().