Tick timer and scheduler 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 after the function name.

Adding a semicolon inside the 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 FreeRTOS task with the correct priority.

FreeRTOS

xTaskCreate(taskFunction, "Task1", configMINIMAL_STACK_SIZE, NULL, [1], NULL);

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A1

BtskIDLE_PRIORITY

C0

DconfigMAX_PRIORITIES

Attempts:

3 left

💡 Hint

Common Mistakes

Using zero as priority which is idle priority.

Using configMAX_PRIORITIES which is out of range.

The priority parameter is usually set to a value between tskIDLE_PRIORITY (0) and configMAX_PRIORITIES - 1. Here, 1 is a valid priority above idle.

3fill in blank

hard

Fix the error in the tick hook function declaration.

FreeRTOS

void vApplicationTickHook[1]

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A()

B(void)

C(int)

D(void*)

Attempts:

3 left

💡 Hint

Common Mistakes

Using empty parentheses which is not valid in C for no-parameter functions.

Adding parameters to the tick hook function.

The tick hook function must be declared with void parameter list: void vApplicationTickHook(void).

4fill in blank

hard

Fill both blanks to create a dictionary of task names and their states.

FreeRTOS

const char* taskStates[] = {"Running", "Ready", "Blocked", "Suspended"};
for(int i = 0; i < [1]; i++) {
    printf("Task %s is %s\n", taskNames[i], taskStates[[2]]);
}

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AconfigMAX_PRIORITIES

BuxTaskGetNumberOfTasks()

Ci

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using configMAX_PRIORITIES which is unrelated to task count.

Using a fixed zero index for all task states.

The loop should run for the number of tasks returned by uxTaskGetNumberOfTasks(). The index i is used to access the current task state.

5fill in blank

hard

Fill all three blanks to correctly implement a tick hook that increments a counter and yields if needed.

FreeRTOS

static BaseType_t xHigherPriorityTaskWoken = pdFALSE;
void vApplicationTickHook(void) {
    [1]++;
    if (xSemaphoreGiveFromISR(xSemaphore, &[2]) == pdTRUE) {
        port[3]();
    }
}

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AulTickCount

BxHigherPriorityTaskWoken

CYIELD_FROM_ISR

DvTaskDelay

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong variable name for the tick count.

Calling vTaskDelay inside an ISR which is invalid.

Not passing the address of the flag variable.

The tick count variable ulTickCount is incremented. The xHigherPriorityTaskWoken flag is passed to the semaphore function. If a higher priority task was woken, portYIELD_FROM_ISR() is called to request a context switch.