Choosing priorities for real applications in FreeRTOS - Mini Project: Build & Apply

Choosing Priorities for Real Applications in FreeRTOS

📖 Scenario: You are developing a simple embedded system using FreeRTOS. The system has three tasks: reading sensor data, controlling an actuator, and logging data. Each task needs a priority to decide which runs first when multiple tasks are ready.Choosing the right priorities helps the system work smoothly and respond quickly to important events.

🎯 Goal: You will create three FreeRTOS tasks with specific priorities to manage sensor reading, actuator control, and data logging. You will assign priorities so that the actuator control runs first, sensor reading second, and logging last.

📋 What You'll Learn

Create three tasks named SensorTask, ActuatorTask, and LoggerTask

Assign priority 3 to ActuatorTask

Assign priority 2 to SensorTask

Assign priority 1 to LoggerTask

Use xTaskCreate to create each task with the correct priority

💡 Why This Matters

🌍 Real World

Embedded systems like robots, home automation, and industrial machines use FreeRTOS tasks with priorities to manage multiple jobs smoothly.

💼 Career

Understanding task priorities is essential for embedded software engineers working on real-time operating systems to ensure timely and reliable system behavior.

1

Create three empty FreeRTOS tasks

Write three empty task functions named SensorTask, ActuatorTask, and LoggerTask. Each should take a void *pvParameters argument and have an infinite loop with vTaskDelay(1000 / portTICK_PERIOD_MS); inside.

FreeRTOS

# Write the three task functions below

# Your code here

Need a hint?

Define each task as a function with void *pvParameters parameter and an infinite loop using for (;;).

2

Declare task handles for each task

Declare three variables of type TaskHandle_t named SensorTaskHandle, ActuatorTaskHandle, and LoggerTaskHandle to hold the task handles.

FreeRTOS

void SensorTask(void *pvParameters) {
    for (;;) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

void ActuatorTask(void *pvParameters) {
    for (;;) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

void LoggerTask(void *pvParameters) {
    for (;;) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

// Declare task handles below
# Your code here

Need a hint?

Use TaskHandle_t type to declare variables for each task handle.

3

Create the three tasks with correct priorities

Use xTaskCreate to create ActuatorTask with priority 3, SensorTask with priority 2, and LoggerTask with priority 1. Pass the address of each task handle variable to store the created task handle.

FreeRTOS

void SensorTask(void *pvParameters) {
    for (;;) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

void ActuatorTask(void *pvParameters) {
    for (;;) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

void LoggerTask(void *pvParameters) {
    for (;;) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

TaskHandle_t SensorTaskHandle;
TaskHandle_t ActuatorTaskHandle;
TaskHandle_t LoggerTaskHandle;

// Create the tasks below
# Your code here

Need a hint?

Use xTaskCreate with parameters: task function, name, stack size (1000), NULL for parameters, priority, and address of task handle.

4

Print the task priorities to verify

Use printf to print the priorities of ActuatorTaskHandle, SensorTaskHandle, and LoggerTaskHandle using uxTaskPriorityGet. Print in this exact format: "ActuatorTask priority: 3\nSensorTask priority: 2\nLoggerTask priority: 1\n".

FreeRTOS

void SensorTask(void *pvParameters) {
    for (;;) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

void ActuatorTask(void *pvParameters) {
    for (;;) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

void LoggerTask(void *pvParameters) {
    for (;;) {
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

TaskHandle_t SensorTaskHandle;
TaskHandle_t ActuatorTaskHandle;
TaskHandle_t LoggerTaskHandle;

xTaskCreate(ActuatorTask, "ActuatorTask", 1000, NULL, 3, &ActuatorTaskHandle);
xTaskCreate(SensorTask, "SensorTask", 1000, NULL, 2, &SensorTaskHandle);
xTaskCreate(LoggerTask, "LoggerTask", 1000, NULL, 1, &LoggerTaskHandle);

// Print the priorities below
# Your code here

Need a hint?

Use printf and uxTaskPriorityGet to print each task's priority exactly as shown.