[Solved] Given this watchdog task snippet:void WatchdogTask(void *pvParameters) { for (;;) { if (xSemaphoreTake(watchdogSemaphore, 0) == pdTRUE) { // Reset... } }What is the main problem with this code? | FreeRTOS

FreeRTOS - Design Patterns for RTOS

Given this watchdog task snippet:

void WatchdogTask(void *pvParameters) {
    for (;;) {
        if (xSemaphoreTake(watchdogSemaphore, 0) == pdTRUE) {
            // Reset received
        } else {
            // No reset, take action
        }
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

What is the main problem with this code?

AThe task deletes itself after one loop

BThe task delays too long after receiving a reset signal

CThe semaphore wait time is zero, so it never blocks to wait for reset signals

DThe semaphore is given incorrectly in the monitored task

Step-by-Step Solution

Solution:

Step 1: Examine semaphore wait time parameter
The call xSemaphoreTake(watchdogSemaphore, 0) means it does not wait and returns immediately.
Step 2: Understand impact on watchdog behavior
Because it never blocks, the watchdog may miss reset signals if they arrive after the check, causing false recovery actions.
Final Answer:
The semaphore wait time is zero, so it never blocks to wait for reset signals -> Option C
Quick Check:
Zero wait means no blocking = D [OK]

Quick Trick: Semaphore wait time zero means no blocking, causing missed signals [OK]

Common Mistakes:

Thinking delay length is the problem
Assuming semaphore is given incorrectly without evidence
Believing task deletes itself here

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Given this watchdog task snippet:

Step 1: Examine semaphore wait time parameter

Step 2: Understand impact on watchdog behavior

Final Answer:

Quick Check:

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