Task function signature in FreeRTOS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this FreeRTOS task function signature code?

Consider this FreeRTOS task function signature and its usage. What will be the output when the task runs?

FreeRTOS

void vTaskCode(void *pvParameters) {
    int *p = (int *)pvParameters;
    printf("Value: %d\n", *p);
}

int main() {
    int x = 10;
    vTaskCode(&x);
    return 0;
}

A Runtime error due to invalid pointer

B Value: 0

C Compilation error due to wrong function signature

D Value: 10

💡 Hint

Remember the task function takes a void pointer parameter which can be cast to any type.

The task function receives a void pointer which is cast to int pointer. The value pointed to is printed correctly as 10.

❓ Predict Output

intermediate

What error occurs with this incorrect FreeRTOS task function signature?

What error will this code produce when compiled or run?

FreeRTOS

void vTaskCode(int pvParameters) {
    printf("Value: %d\n", pvParameters);
}

int main() {
    int x = 5;
    vTaskCode(x);
    return 0;
}

A Compilation error due to wrong parameter type

B Prints: Value: 5

C Runtime error due to invalid pointer

D No output

💡 Hint

Check the parameter type expected by FreeRTOS task functions.

Although the signature is not the standard FreeRTOS task signature, this code compiles and prints 5 because the function is called directly.

🧠 Conceptual

advanced

Which is the correct FreeRTOS task function signature?

Select the correct function signature for a FreeRTOS task function.

A void TaskFunction()

B int TaskFunction(int pvParameters)

C void TaskFunction(void *pvParameters)

D void TaskFunction(int *pvParameters)

💡 Hint

FreeRTOS task functions always take a void pointer parameter and return void.

FreeRTOS task functions must have the signature void function(void *pvParameters) to be compatible with the scheduler.

❓ Predict Output

advanced

What is the output of this FreeRTOS task function with pointer parameter?

What will this code print when the task function runs?

FreeRTOS

void vTaskCode(void *pvParameters) {
    char *msg = (char *)pvParameters;
    printf("Message: %s\n", msg);
}

int main() {
    char message[] = "Hello FreeRTOS";
    vTaskCode(message);
    return 0;
}

A Message: Hello FreeRTOS

B Compilation error due to wrong cast

C Message: (null)

D Runtime error due to invalid pointer

💡 Hint

Casting void pointer to char pointer is valid for string parameters.

The void pointer is cast to char pointer correctly and prints the string.

🧠 Conceptual

expert

Why must FreeRTOS task functions have the signature void function(void *pvParameters)?

Choose the best explanation for why FreeRTOS task functions require this signature.

A Because the scheduler expects a function returning void and taking a generic pointer to pass any data.

B Because void return type allows returning task status codes to the scheduler.

C Because the parameter must always be an integer representing task ID.

D Because FreeRTOS tasks cannot accept any parameters.

💡 Hint

Think about how the scheduler manages tasks and passes data.

The scheduler calls task functions expecting void return and a void pointer parameter to pass any user data generically.