[Solved] Identify the error in this ISR code snippet:void ISR_Handler(void) { BaseType_t higherPriorityTaskWoken = pdFALSE; xSemaphoreGive(semaphore); if (higherPriorityTaskWoken) { portYIELD_FROM_ISR();... | FreeRTOS

FreeRTOS - Interrupt Management

Identify the error in this ISR code snippet:

void ISR_Handler(void) {
    BaseType_t higherPriorityTaskWoken = pdFALSE;
    xSemaphoreGive(semaphore);
    if (higherPriorityTaskWoken) {
        portYIELD_FROM_ISR();
    }
}

What is the problem here?

AThe variable <code>higherPriorityTaskWoken</code> should be global.

BThe semaphore is given twice causing overflow.

CThe <code>portYIELD_FROM_ISR()</code> call is outside the ISR.

DThe <code>higherPriorityTaskWoken</code> variable is not passed to <code>xSemaphoreGiveFromISR</code>.

Step-by-Step Solution

Solution:

Step 1: Check function used for semaphore give
The code uses xSemaphoreGive, which is not safe inside ISR context.
Step 2: Correct ISR-safe function usage
Inside ISR, xSemaphoreGiveFromISR must be used with higherPriorityTaskWoken passed by reference to track task wake.
Final Answer:
The higherPriorityTaskWoken variable is not passed to xSemaphoreGiveFromISR. -> Option D
Quick Check:
Use FromISR functions with higherPriorityTaskWoken [OK]

Quick Trick: Always pass higherPriorityTaskWoken to FromISR functions [OK]

Common Mistakes:

Using normal API functions inside ISR
Not passing higherPriorityTaskWoken pointer
Declaring higherPriorityTaskWoken as global unnecessarily

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Identify the error in this ISR code snippet:

Step 1: Check function used for semaphore give

Step 2: Correct ISR-safe function usage

Final Answer:

Quick Check:

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