[Solved] Which of the following is the correct syntax to send an item to a queue from an ISR in FreeRTOS? — Ans: xQueueSendFromISR(queueHandle, &item, &higherPriorityTaskWoken); | FreeRTOS

FreeRTOS - Interrupt Management

Which of the following is the correct syntax to send an item to a queue from an ISR in FreeRTOS?

AxQueueSend(queueHandle, &item, portMAX_DELAY);

BxQueueSendFromISR(queueHandle, &item, &higherPriorityTaskWoken);

CxQueueSendFromISR(queueHandle, item, NULL);

DxQueueSend(queueHandle, item, 0);

Step-by-Step Solution

Solution:

Step 1: Identify ISR-safe queue send function
Inside ISR, use xQueueSendFromISR which requires a pointer to the item and a pointer to the wake flag.
Step 2: Check parameters correctness
Parameters must be queue handle, address of item, and address of higherPriorityTaskWoken flag.
Final Answer:
xQueueSendFromISR(queueHandle, &item, &higherPriorityTaskWoken); -> Option B
Quick Check:
ISR queue send syntax = xQueueSendFromISR(queueHandle, &item, &higherPriorityTaskWoken); [OK]

Quick Trick: Use &item and &flag pointers in FromISR functions [OK]

Common Mistakes:

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Which of the following is the correct syntax to send an item to a queue from an ISR in FreeRTOS?