FreeRTOS - Interrupt Management
In a system using FreeRTOS, you want to safely give a mutex from an ISR and ensure the highest priority task runs immediately if unblocked. Which code snippet correctly implements this?
In a system using FreeRTOS, you want to safely give a mutex from an ISR and ensure the highest priority task runs immediately if unblocked. Which code snippet correctly implements this?
hard📝 Application Q9 of 15
Step-by-Step Solution
Solution:
Step 1: Use FromISR function to give mutex inside ISR
UsexSemaphoreGiveFromISRwith a pointer toxHigherPriorityTaskWoken.Step 2: Call portYIELD_FROM_ISR with the wake flag
This triggers a context switch if a higher priority task was unblocked.Final Answer:
BaseType_t xHigherPriorityTaskWoken = pdFALSE; xSemaphoreGiveFromISR(xMutex, &xHigherPriorityTaskWoken); portYIELD_FROM_ISR(xHigherPriorityTaskWoken); -> Option AQuick Check:
Mutex give from ISR with yield flag = BaseType_t xHigherPriorityTaskWoken = pdFALSE; xSemaphoreGiveFromISR(xMutex, &xHigherPriorityTaskWoken); portYIELD_FROM_ISR(xHigherPriorityTaskWoken); [OK]
Quick Trick: Always pass wake flag pointer and yield after FromISR mutex give [OK]
Common Mistakes:
- Using normal xSemaphoreGive inside ISR
- Not passing wake flag pointer
- Calling yield without checking flag
Master "Interrupt Management" in FreeRTOS
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