[Solved] Given this code snippet, what is the expected behavior?BaseType_t xHigherPriorityTaskWoken = pdFALSE; xTaskNotifyGiveFromISR(taskHandle, &xHigherPriorityTaskWoken);... | FreeRTOS

FreeRTOS - Task Notifications

Given this code snippet, what is the expected behavior?

BaseType_t xHigherPriorityTaskWoken = pdFALSE;
xTaskNotifyGiveFromISR(taskHandle, &xHigherPriorityTaskWoken);
if(xHigherPriorityTaskWoken) {
  portYIELD_FROM_ISR();
}

AThe ISR causes a deadlock by waiting for the task

BThe ISR blocks until the task processes the notification

CThe ISR notifies the task and yields if a higher priority task was woken

DThe notification is ignored if the task is already running

Step-by-Step Solution

Solution:

Step 1: Understand xTaskNotifyGiveFromISR usage
This function sends a notification from an ISR and sets xHigherPriorityTaskWoken if a higher priority task was woken.
Step 2: Analyze portYIELD_FROM_ISR call
If a higher priority task was woken, portYIELD_FROM_ISR requests a context switch to that task immediately.
Final Answer:
The ISR notifies the task and yields if a higher priority task was woken -> Option C
Quick Check:
Notify + yield if higher priority task woken [OK]

Quick Trick: Yield from ISR only if higher priority task is woken [OK]

Common Mistakes:

Assuming ISR blocks until task runs
Thinking notification is ignored if task runs
Believing ISR causes deadlock

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Given this code snippet, what is the expected behavior?

Step 1: Understand xTaskNotifyGiveFromISR usage

Step 2: Analyze portYIELD_FROM_ISR call

Final Answer:

Quick Check:

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