Why task notifications are lightweight in FreeRTOS - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to send a task notification in FreeRTOS.

FreeRTOS

xTaskNotifyGive([1]);

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AxTaskToNotify

BxTaskHandle

CxQueueHandle

DxSemaphore

Attempts:

3 left

💡 Hint

Common Mistakes

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

Confusing the task handle variable name.

The function xTaskNotifyGive() sends a notification to the specified task handle, which is xTaskToNotify here.

2fill in blank

medium

Complete the code to wait for a task notification with a timeout.

FreeRTOS

ulTaskNotifyTake([1], pdMS_TO_TICKS(1000));

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ApdPASS

BpdTRUE

CportMAX_DELAY

DpdFALSE

Attempts:

3 left

💡 Hint

Common Mistakes

Using pdFALSE which does not clear the notification value.

Confusing the parameter with timeout values.

The first parameter pdTRUE clears the notification value on exit, which is common when waiting for a notification.

3fill in blank

hard

Fix the error in the code to send a notification with a value.

FreeRTOS

xTaskNotify([1], 0x01, eSetBits);

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AxTaskToNotify

BxTaskHandle

CNULL

DxQueueHandle

Attempts:

3 left

💡 Hint

Common Mistakes

Passing NULL or queue handle instead of task handle.

Using an undefined variable name.

The first argument must be the task handle to notify, which is xTaskToNotify.

4fill in blank

hard

Fill both blanks to create a task notification value and check if a bit is set.

FreeRTOS

uint32_t notifValue = [1];
if (notifValue [2] 0x01) {
    // Bit 0 is set
}

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AulTaskNotifyValueClear(NULL, 0x01)

B&

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using bitwise OR instead of AND for checking bits.

Not clearing notification bits properly.

The function ulTaskNotifyValueClear() reads and clears bits, and the bitwise AND operator & checks if bit 0 is set.

5fill in blank

hard

Fill all three blanks to send a notification, wait for it, and clear the value.

FreeRTOS

xTaskNotify([1], 0x02, eSetBits);
uint32_t value = ulTaskNotifyTake([2], portMAX_DELAY);
value = ulTaskNotifyValueClear([3], 0x02);

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

AxTaskToNotify

BpdTRUE

DpdFALSE

Attempts:

3 left

💡 Hint

Common Mistakes

Using different task handles for send and clear.

Using pdFALSE which does not clear notification value.

Use the task handle xTaskToNotify to send and clear notifications, and pdTRUE to clear the notification value when waiting.