[Solved] Identify the error in this nested interrupt handling code snippet:void ISR_UART(void) { BaseType_t xHigherPriorityTaskWoken = pdFALSE; xQueueSendFromISR(xQueue, &data, NULL);... | FreeRTOS

FreeRTOS - Interrupt Management

Identify the error in this nested interrupt handling code snippet:

void ISR_UART(void) {
    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
    xQueueSendFromISR(xQueue, &data, NULL);
    portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
}

ABaseType_t should be int instead

BportYIELD_FROM_ISR should not be called inside ISR

CxQueueSendFromISR cannot be used in ISRs

DxHigherPriorityTaskWoken should be passed to xQueueSendFromISR

Step-by-Step Solution

Solution:

Step 1: Check xQueueSendFromISR parameters
The function requires a pointer to xHigherPriorityTaskWoken to update it if a higher priority task is woken.
Step 2: Identify missing argument
Passing NULL means xHigherPriorityTaskWoken is never updated, so portYIELD_FROM_ISR may not yield correctly.
Final Answer:
xHigherPriorityTaskWoken should be passed to xQueueSendFromISR -> Option D
Quick Check:
Pass xHigherPriorityTaskWoken pointer to FromISR APIs [OK]

Quick Trick: Always pass xHigherPriorityTaskWoken pointer to FromISR APIs [OK]

Common Mistakes:

Passing NULL instead of &xHigherPriorityTaskWoken
Calling portYIELD_FROM_ISR without updating flag
Using wrong variable types for task woken flag

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More FreeRTOS Quizzes

Identify the error in this nested interrupt handling code snippet:

Step 1: Check xQueueSendFromISR parameters

Step 2: Identify missing argument

Final Answer:

Quick Check:

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