[Solved] Consider this code snippet:EventGroupHandle_t xEventGroup = xEv... EventBits_t bits = xEventGroupWaitBits(xEventGroup, 0x01, pdTRUE, pdFALSE, portMAX_DELAY);What is the value of bits after execution? | FreeRTOS

FreeRTOS - Design Patterns for RTOS

Consider this code snippet:

EventGroupHandle_t xEventGroup = xEventGroupCreate();
xEventGroupSetBits(xEventGroup, 0x01);
EventBits_t bits = xEventGroupWaitBits(xEventGroup, 0x01, pdTRUE, pdFALSE, portMAX_DELAY);

What is the value of bits after execution?

A0xFF

B0x00

C0x01

DUndefined

Step-by-Step Solution

Solution:

Step 1: Analyze event bits set and wait parameters
The bit 0x01 is set before waiting. The wait clears bits after return (pdTRUE).
Step 2: Determine returned bits value
The function returns the bits that were set before clearing. So bits = 0x01.
Final Answer:
0x01 -> Option C
Quick Check:
Returned bits = bits set before clearing [OK]

Quick Trick: WaitBits returns bits set before clearing if clear on exit is true [OK]

Common Mistakes:

Assuming bits cleared before return
Expecting zero after clearing bits
Confusing return value with current bits

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Consider this code snippet:

Step 1: Analyze event bits set and wait parameters

Step 2: Determine returned bits value

Final Answer:

Quick Check:

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