Deferred interrupt processing architecture in FreeRTOS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an interrupt service routine (ISR) in FreeRTOS.

FreeRTOS

void v[1]Handler(void) {
    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
    // ISR code here
}

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

AADC

BTimer

CGPIO

DUART

Attempts:

3 left

💡 Hint

Common Mistakes

Using a generic name instead of a specific peripheral name.

Forgetting to declare the ISR with the correct signature.

The ISR name typically reflects the hardware interrupt source, such as UARTHandler for UART interrupts.

2fill in blank

medium

Complete the code to notify a task from an ISR using FreeRTOS API.

FreeRTOS

vTaskNotifyGiveFromISR(xTaskHandle, &[1]);

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

ApdTRUE

BxHigherPriorityTaskWoken

CpdFALSE

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Passing pdTRUE or pdFALSE directly instead of the pointer variable.

Passing NULL which disables context switch notification.

The parameter is a pointer to a variable that indicates if a context switch is required.

3fill in blank

hard

Fix the error in the ISR to correctly perform deferred interrupt processing.

FreeRTOS

void vISR_Handler(void) {
    BaseType_t [1] = pdFALSE;
    // Clear interrupt flag
    vTaskNotifyGiveFromISR(xTaskHandle, &xHigherPriorityTaskWoken);
    portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
}

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

AxHigherPriorityTaskWoken

BxTaskWoken

CxInterruptFlag

DxNotifyFlag

Attempts:

3 left

💡 Hint

Common Mistakes

Using an undefined variable name.

Not calling portYIELD_FROM_ISR with the correct variable.

The variable xHigherPriorityTaskWoken must be declared and used to request a context switch.

4fill in blank

hard

Fill both blanks to create a deferred interrupt processing task that waits for notification.

FreeRTOS

void vDeferredTask(void *pvParameters) {
    for(;;) {
        ulTaskNotifyTake([1], [2]);
        // Process interrupt data here
    }
}

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

ApdTRUE

BportMAX_DELAY

CpdFALSE

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using pdFALSE instead of pdTRUE for clearing notification.

Using 0 instead of portMAX_DELAY causing no wait.

ulTaskNotifyTake uses pdTRUE to clear the notification count and portMAX_DELAY to wait indefinitely.

5fill in blank

hard

Fill all three blanks to implement a deferred interrupt processing system with ISR notification and task wait.

FreeRTOS

void vISR_Handler(void) {
    BaseType_t [1] = pdFALSE;
    vTaskNotifyGiveFromISR(xTaskHandle, &[2]);
    [3]YIELD_FROM_ISR(xHigherPriorityTaskWoken);
}

void vDeferredTask(void *pvParameters) {
    for(;;) {
        ulTaskNotifyTake(pdTRUE, portMAX_DELAY);
        // Handle deferred processing
    }
}

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

AxHigherPriorityTaskWoken

BxTaskWoken

Dport

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Omitting the 'port' prefix in portYIELD_FROM_ISR.

The variable xHigherPriorityTaskWoken is declared and used consistently. The macro portYIELD_FROM_ISR is called with the prefix 'port'.