xTaskNotifyGive() as lightweight semaphore in FreeRTOS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to notify a task using xTaskNotifyGive().

FreeRTOS

xTaskNotifyGive([1]);

Drag options to blanks, or click blank then click option'

AxTaskHandle

BxQueue

CxSemaphore

DxTaskToNotify

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a semaphore or queue handle instead of a task handle.

Using an undefined variable as the task handle.

The function xTaskNotifyGive() requires the handle of the task to notify. Here, xTaskToNotify is the correct task handle.

2fill in blank

medium

Complete the code to wait for a notification as a lightweight semaphore using ulTaskNotifyTake().

FreeRTOS

ulTaskNotifyTake([1], portMAX_DELAY);

Drag options to blanks, or click blank then click option'

A0

BpdTRUE

CpdFALSE

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Passing pdTRUE which clears the count immediately.

Passing numeric values like 0 or 1 instead of pdFALSE or pdTRUE.

The first parameter to ulTaskNotifyTake() is ClearCountOnExit. Passing pdFALSE means the count is not cleared on exit, which is typical for semaphore behavior.

3fill in blank

hard

Fix the error in the code to correctly use xTaskNotifyGive() as a semaphore signal.

FreeRTOS

void signalTask() {
    xTaskNotifyGive([1]);
}

Drag options to blanks, or click blank then click option'

AxTaskToNotify

BxTaskHandle

CNULL

DxSemaphore

Attempts:

3 left

💡 Hint

Common Mistakes

Passing NULL which causes no task to be notified.

Passing a semaphore handle instead of a task handle.

The function xTaskNotifyGive() must be called with a valid task handle. Using xTaskToNotify ensures the correct task is notified.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps task names to their notification counts if count is greater than zero.

FreeRTOS

taskNotifyCounts = {taskName: [1] for taskName, count in taskCounts.items() if count [2] 0}

Drag options to blanks, or click blank then click option'

Acount

B==

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using equality (==) instead of greater than (>) in the condition.

Mapping to taskName instead of count.

The dictionary comprehension maps taskName to count only if count > 0.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase task names to their counts if count is less than 5.

FreeRTOS

filteredCounts = [1]: [2] for task, count in counts.items() if count [3] 5}

Drag options to blanks, or click blank then click option'

Atask.upper()

Bcount

C<

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using greater than (>) instead of less than (<) in the condition.

Mapping task names without converting to uppercase.

The comprehension maps uppercase task names to counts where count is less than 5.