Why runtime monitoring catches RTOS bugs in FreeRTOS - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start the FreeRTOS scheduler.

FreeRTOS

vTaskStartScheduler[1];

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A()

B;

C{}

D[]

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting parentheses causes a syntax error.

The function vTaskStartScheduler() starts the RTOS scheduler and requires parentheses even if no arguments are passed.

2fill in blank

medium

Complete the code to create a task with FreeRTOS API.

FreeRTOS

xTaskCreate(TaskFunction, "Task1", 1000, NULL, [1], NULL);

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A0

BvTaskStartScheduler

C1

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using NULL or zero may create a task with no priority.

The priority parameter in xTaskCreate is an integer. Here, 1 sets the task priority.

3fill in blank

hard

Fix the error in the task delay call to avoid runtime bugs.

FreeRTOS

vTaskDelay([1]);

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A1000 * portTICK_PERIOD_MS

B1000 / portTICK_PERIOD_MS

C1000

DportTICK_PERIOD_MS

Attempts:

3 left

💡 Hint

Common Mistakes

Using raw milliseconds causes incorrect delays and timing bugs.

FreeRTOS expects delay time in ticks. Dividing milliseconds by portTICK_PERIOD_MS converts ms to ticks correctly.

4fill in blank

hard

Fill both blanks to correctly check if a queue send was successful.

FreeRTOS

if (xQueueSend(queue, &data, [1]) == [2]) { /* success */ }

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AportMAX_DELAY

BpdPASS

C0

DpdFAIL

Attempts:

3 left

💡 Hint

Common Mistakes

Using zero timeout causes immediate failure if queue is full.

xQueueSend uses portMAX_DELAY to wait indefinitely. It returns pdPASS on success.

5fill in blank

hard

Fill all three blanks to create a runtime monitoring hook for stack overflow detection.

FreeRTOS

void vApplicationStackOverflowHook(TaskHandle_t [1], char *[2]) {
    [3];
}

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AxTask

BpcTaskName

CtaskDISABLE_INTERRUPTS()

DvTaskDelete(xTask)

Attempts:

3 left

💡 Hint

Common Mistakes

Calling vTaskDelete inside the hook may cause issues.

The hook receives the task handle xTask and task name pcTaskName. Disabling interrupts with taskDISABLE_INTERRUPTS() prevents further damage.