Common RTOS bugs and debugging strategies in FreeRTOS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a FreeRTOS task that runs the function taskFunction.

FreeRTOS

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

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AtaskFunction

BvTaskStartScheduler

CxQueueCreate

DvTaskDelay

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the scheduler start function instead of the task function.

The function taskFunction is passed to xTaskCreate to define the task's code.

2fill in blank

medium

Complete the code to delay a task for 500 milliseconds using FreeRTOS API.

FreeRTOS

vTaskDelay([1]);

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ApdMS_TO_TICKS(500)

B500 * portTICK_PERIOD_MS

C500 / portTICK_PERIOD_MS

D500

Attempts:

3 left

💡 Hint

Common Mistakes

Passing raw milliseconds instead of ticks.

Use pdMS_TO_TICKS(500) to convert milliseconds to ticks for vTaskDelay.

3fill in blank

hard

Fix the error in the code that causes a deadlock when two tasks try to take the same mutex.

FreeRTOS

if(xSemaphoreTake([1], portMAX_DELAY) == pdTRUE) {
    // critical section
    xSemaphoreGive([1]);
}

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AtaskHandle

Bqueue1

Cmutex1

Dtimer1

Attempts:

3 left

💡 Hint

Common Mistakes

Using different handles for take and give.

Using a queue handle instead of a mutex.

The mutex mutex1 must be taken and given properly to avoid deadlocks.

4fill in blank

hard

Fill both blanks to correctly check if a queue is full before sending data.

FreeRTOS

if(uxQueueSpacesAvailable([1]) [2] 0) {
    xQueueSend([1], &data, 0);
}

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AqueueHandle

B>

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using different queue handles.

Checking if spaces equal zero instead of greater than zero.

Check if the queue queueHandle has space available (greater than 0) before sending.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps task names to their stack high water marks if the mark is less than 100.

FreeRTOS

{ [1]: [2] for [1] in tasks if uxTaskGetStackHighWaterMark([1]) [3] 100 }

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Atask

BuxTaskGetStackHighWaterMark(task)

C<

Dtask.name

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for key and iteration.

Using wrong comparison operators.

This comprehension creates a dictionary with task handles as keys and their stack high water marks as values, filtering those below 100.