What is the expected behavior of xSemaphoreGiveFromISR() when called inside an ISR and the semaphore unblocks a higher priority task?

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FreeRTOS - Interrupt Management

What is the expected behavior of xSemaphoreGiveFromISR() when called inside an ISR and the semaphore unblocks a higher priority task?

AIt sets the <code>higherPriorityTaskWoken</code> flag to pdTRUE

BIt blocks the ISR until the task runs

CIt disables all interrupts until the task finishes

DIt returns an error code

Step-by-Step Solution

Solution:

Step 1: Understand xSemaphoreGiveFromISR() role
This function releases a semaphore from ISR and can unblock a waiting task.
Step 2: Check flag behavior when unblocking higher priority task
If a higher priority task is unblocked, the function sets higherPriorityTaskWoken to pdTRUE to indicate a context switch may be needed.
Final Answer:
It sets the higherPriorityTaskWoken flag to pdTRUE -> Option A
Quick Check:
Semaphore give from ISR sets wake flag = pdTRUE [OK]

Quick Trick: FromISR semaphore give sets wake flag if task unblocked [OK]

Common Mistakes:

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