vTaskDelayUntil() for precise timing in FreeRTOS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare the variable that stores the last wake time for precise delay.

FreeRTOS

TickType_t [1] = xTaskGetTickCount();

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

AxLastWakeTime

BdelayTime

CtickCount

DlastTick

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name that does not match the expected naming convention.

Not initializing the variable with the current tick count.

The variable xLastWakeTime stores the last wake time and is used with vTaskDelayUntil() for precise timing.

2fill in blank

medium

Complete the code to delay the task precisely for 100 ticks using vTaskDelayUntil.

FreeRTOS

vTaskDelayUntil(&[1], pdMS_TO_TICKS(100));

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

AdelayTime

BlastTick

CtickCount

DxLastWakeTime

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the wrong variable or a non-pointer argument.

Using vTaskDelay() instead of vTaskDelayUntil().

The function vTaskDelayUntil() requires a pointer to xLastWakeTime to maintain precise periodic timing.

3fill in blank

hard

Fix the error in the code to correctly use vTaskDelayUntil for a 500 ms delay.

FreeRTOS

TickType_t xLastWakeTime = xTaskGetTickCount();
vTaskDelayUntil([1], pdMS_TO_TICKS(500));

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

A&xLastWakeTime

BxLastWakeTime

C*xLastWakeTime

DxLastWakeTime&

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the variable without the address operator.

Using incorrect pointer syntax.

vTaskDelayUntil() requires a pointer to the last wake time variable, so &xLastWakeTime is correct.

4fill in blank

hard

Fill both blanks to create a periodic task that delays precisely for 200 ms.

FreeRTOS

TickType_t [1] = xTaskGetTickCount();
vTaskDelayUntil(&[2], pdMS_TO_TICKS(200));

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

AxLastWakeTime

BdelayTime

DtickStart

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for declaration and usage.

Not passing the address of the variable in the function call.

Both blanks should be xLastWakeTime to correctly track and update the last wake time for precise delays.

5fill in blank

hard

Fill all three blanks to implement a task that toggles an LED every 250 ms using vTaskDelayUntil.

FreeRTOS

void vTaskToggleLED(void *pvParameters) {
    TickType_t [1] = xTaskGetTickCount();
    for(;;) {
        toggleLED();
        vTaskDelayUntil(&[2], pdMS_TO_TICKS([3]));
    }
}

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

AxLastWakeTime

C250

D200

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in declaration and function call.

Setting the wrong delay time.

Not passing the address of the variable.

The variable xLastWakeTime is used to track the last wake time, and the delay is set to 250 ms for toggling the LED periodically.