Real-time vs general-purpose OS in FreeRTOS - Hands-On Comparison

Real-time vs General-purpose OS Task Scheduling

📖 Scenario: You are working on a small embedded device that controls a home automation system. It needs to handle urgent tasks like turning off the heater immediately when the temperature is too high, and also less urgent tasks like updating the display every few seconds.This project will help you understand how a real-time operating system (RTOS) like FreeRTOS schedules tasks differently from a general-purpose OS.

🎯 Goal: You will create two tasks in FreeRTOS: one high-priority task that simulates an urgent sensor check, and one low-priority task that simulates a display update. You will see how the RTOS runs the urgent task immediately when needed, unlike a general-purpose OS that might delay it.

📋 What You'll Learn

Create two FreeRTOS tasks with different priorities

Use vTaskDelay to simulate task timing

Print messages to show which task is running

Observe task switching behavior

💡 Why This Matters

🌍 Real World

Embedded systems like home automation, robotics, and automotive use real-time OS to handle urgent tasks reliably.

💼 Career

Understanding RTOS task scheduling is essential for embedded software engineers and developers working on time-critical applications.

1

Create two FreeRTOS tasks

Write code to create two tasks named UrgentTask and DisplayTask using xTaskCreate. Use the function prototypes void UrgentTask(void *pvParameters) and void DisplayTask(void *pvParameters). Do not start the scheduler yet.

FreeRTOS

// Create two tasks UrgentTask and DisplayTask using xTaskCreate
// Your code here

Need a hint?

Use xTaskCreate to create tasks with their function names and priorities.

2

Add task delays and print messages

Inside UrgentTask, add a printf statement to print "Urgent task running" before vTaskDelay(pdMS_TO_TICKS(1000)). Inside DisplayTask, add a printf statement to print "Display task running" before vTaskDelay(pdMS_TO_TICKS(2000)).

FreeRTOS

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

void UrgentTask(void *pvParameters) {
    for (;;) {
        // Print urgent task message
        // Your code here
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

void DisplayTask(void *pvParameters) {
    for (;;) {
        // Print display task message
        // Your code here
        vTaskDelay(pdMS_TO_TICKS(2000));
    }
}

int main(void) {
    xTaskCreate(UrgentTask, "UrgentTask", 1000, NULL, 2, NULL);
    xTaskCreate(DisplayTask, "DisplayTask", 1000, NULL, 1, NULL);
    // Scheduler not started yet
    return 0;
}

Need a hint?

Use printf before the delay in each task to show which task runs.

3

Start the FreeRTOS scheduler

In the main function, after creating the tasks, add the call to vTaskStartScheduler() to start the RTOS scheduler.

FreeRTOS

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

void UrgentTask(void *pvParameters) {
    for (;;) {
        printf("Urgent task running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

void DisplayTask(void *pvParameters) {
    for (;;) {
        printf("Display task running\n");
        vTaskDelay(pdMS_TO_TICKS(2000));
    }
}

int main(void) {
    xTaskCreate(UrgentTask, "UrgentTask", 1000, NULL, 2, NULL);
    xTaskCreate(DisplayTask, "DisplayTask", 1000, NULL, 1, NULL);
    // Start the scheduler below
    // Your code here
    return 0;
}

Need a hint?

Call vTaskStartScheduler() to begin running the tasks.

4

Observe and print the task switching output

Run the program and observe the printed output. Write a printf statement after vTaskStartScheduler() in main to print "Scheduler ended". Note that this line should never run if the scheduler works correctly. The expected output should show alternating messages from UrgentTask and DisplayTask.

FreeRTOS

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

void UrgentTask(void *pvParameters) {
    for (;;) {
        printf("Urgent task running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

void DisplayTask(void *pvParameters) {
    for (;;) {
        printf("Display task running\n");
        vTaskDelay(pdMS_TO_TICKS(2000));
    }
}

int main(void) {
    xTaskCreate(UrgentTask, "UrgentTask", 1000, NULL, 2, NULL);
    xTaskCreate(DisplayTask, "DisplayTask", 1000, NULL, 1, NULL);
    vTaskStartScheduler();
    // Print Scheduler ended below
    // Your code here
    return 0;
}

Need a hint?

The scheduler runs tasks repeatedly. You should see both messages printed repeatedly. The line "Scheduler ended" should not appear unless the scheduler stops.