Graceful shutdown sequence in FreeRTOS - Mini Project: Build & Apply

Graceful shutdown sequence

📖 Scenario: You are developing a FreeRTOS application for a smart home device. The device needs to shut down gracefully when a shutdown signal is received. This means it should stop accepting new tasks, finish current tasks, release resources, and then power off safely.

🎯 Goal: Build a graceful shutdown sequence in FreeRTOS that uses a flag to signal shutdown, stops task creation, waits for running tasks to finish, and then prints a shutdown complete message.

📋 What You'll Learn

Create a global flag variable shutdown_requested initialized to false.

Create a task called WorkerTask that runs a loop checking shutdown_requested and exits when it is true.

Create a task called ShutdownTask that sets shutdown_requested to true after a delay.

Print "Shutdown complete" after all tasks have stopped.

💡 Why This Matters

🌍 Real World

Smart devices and embedded systems often need to stop safely to avoid data loss or hardware damage.

💼 Career

Embedded software engineers must implement graceful shutdowns to ensure reliable and safe device operation.

1

Create the shutdown flag variable

Create a global variable called shutdown_requested of type bool and initialize it to false.

FreeRTOS

# Your code here

Need a hint?

This flag will tell tasks when to stop running.

2

Create the WorkerTask that checks the shutdown flag

Create a FreeRTOS task function called WorkerTask that runs an infinite loop. Inside the loop, check if shutdown_requested is true. If it is, break the loop to exit the task. Use vTaskDelay(100 / portTICK_PERIOD_MS) inside the loop to simulate work.

FreeRTOS

#include 

volatile bool shutdown_requested = false;

// Your code here

Need a hint?

The task should stop running when shutdown_requested becomes true.

3

Create the ShutdownTask to trigger shutdown

Create a FreeRTOS task function called ShutdownTask that waits for 500 milliseconds using vTaskDelay(500 / portTICK_PERIOD_MS) and then sets shutdown_requested to true. After setting the flag, delete itself with vTaskDelete(NULL).

FreeRTOS

#include 
#include "FreeRTOS.h"
#include "task.h"

volatile bool shutdown_requested = false;

void WorkerTask(void *pvParameters) {
    while (1) {
        if (shutdown_requested) {
            break;
        }
        vTaskDelay(100 / portTICK_PERIOD_MS);
    }
    vTaskDelete(NULL);
}

// Your code here

Need a hint?

This task triggers the shutdown after a short delay.

4

Print shutdown complete after tasks stop

In the main function, create the WorkerTask and ShutdownTask using xTaskCreate. Then start the scheduler with vTaskStartScheduler(). After the scheduler ends, print "Shutdown complete" using printf.

FreeRTOS

#include 
#include "FreeRTOS.h"
#include "task.h"
#include 

volatile bool shutdown_requested = false;

void WorkerTask(void *pvParameters) {
    while (1) {
        if (shutdown_requested) {
            break;
        }
        vTaskDelay(100 / portTICK_PERIOD_MS);
    }
    vTaskDelete(NULL);
}

void ShutdownTask(void *pvParameters) {
    vTaskDelay(500 / portTICK_PERIOD_MS);
    shutdown_requested = true;
    vTaskDelete(NULL);
}

int main(void) {
    // Your code here
}

Need a hint?

The scheduler runs tasks until shutdown is requested. After it ends, print the shutdown message.