Preemptive scheduling behavior in FreeRTOS - Interactive Code Practice

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 the parentheses and writing just the function name.

Adding curly braces instead of parentheses.

The function vTaskStartScheduler() starts the FreeRTOS scheduler and takes no parameters, so it requires parentheses ().

2fill in blank

medium

Complete the code to create a task with priority 2.

FreeRTOS

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

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A2

B1

C3

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using priority 0 which is the lowest priority.

Confusing the stack size with priority.

The priority parameter in xTaskCreate sets the task priority. Here, priority 2 is required.

3fill in blank

hard

Fix the error in the task delay function to yield control correctly.

FreeRTOS

vTaskDelay([1]);

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AportTICK_PERIOD_MS

B1000

C1000 * portTICK_PERIOD_MS

D1000 / portTICK_PERIOD_MS

Attempts:

3 left

💡 Hint

Common Mistakes

Passing milliseconds directly without conversion.

Multiplying instead of dividing by portTICK_PERIOD_MS.

The vTaskDelay() function expects a delay in ticks. To delay 1000 milliseconds, divide by portTICK_PERIOD_MS.

4fill in blank

hard

Fill both blanks to create a preemptive scheduler configuration.

FreeRTOS

configUSE_PREEMPTION = [1];
configMAX_PRIORITIES = [2];

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A1

B0

C5

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Setting configUSE_PREEMPTION to 0 disables preemption.

Choosing too few or too many priorities.

Setting configUSE_PREEMPTION to 1 enables preemptive scheduling. configMAX_PRIORITIES defines the number of priority levels; 5 is a common choice.

5fill in blank

hard

Fill all three blanks to correctly implement a task function that yields control.

FreeRTOS

void TaskFunction(void *pvParameters) {
    for(;;) {
        // Task code here
        [1]();
        [2](10 / [3]);
    }
}

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AvTaskDelay

BvTaskDelayUntil

CportTICK_PERIOD_MS

DtaskYIELD

Attempts:

3 left

💡 Hint

Common Mistakes

Using vTaskDelayUntil without proper tick count variable.

Forgetting to convert milliseconds to ticks.

taskYIELD() forces the task to yield control immediately. vTaskDelay() delays the task for a number of ticks, which is calculated by dividing milliseconds by portTICK_PERIOD_MS.