Tick timer and scheduler in FreeRTOS - Mini Project: Build & Apply

Tick Timer and Scheduler in FreeRTOS

📖 Scenario: You are working on a simple embedded system using FreeRTOS. Your task is to set up the tick timer and create a basic scheduler that switches between two tasks periodically.

🎯 Goal: Build a FreeRTOS program that initializes the tick timer, creates two tasks, and uses the scheduler to switch between them, printing messages to show task execution.

📋 What You'll Learn

Create two tasks named Task1 and Task2

Set up the FreeRTOS tick timer with a tick rate of 1000 Hz

Use the FreeRTOS scheduler to switch between the tasks

Each task should print a message indicating it is running

Run the scheduler to start task switching

💡 Why This Matters

🌍 Real World

Embedded systems often use FreeRTOS to manage multiple tasks like sensor reading, communication, and control loops efficiently.

💼 Career

Understanding FreeRTOS tick timer and scheduler is essential for embedded software developers working on real-time applications.

1

Create two FreeRTOS tasks

Write code to create two tasks named Task1 and Task2 using xTaskCreate. Each task should run a function that prints a unique message in an infinite loop with a delay.

FreeRTOS

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

void Task1(void *pvParameters) {
    while(1) {
        printf("Task 1 is running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

void Task2(void *pvParameters) {
    while(1) {
        printf("Task 2 is running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

int main(void) {
    // Create Task1 using xTaskCreate
    // Create Task2 using xTaskCreate
    return 0;
}

Need a hint?

Use xTaskCreate to create each task with the function name, a name string, stack size, parameters as NULL, priority 1, and no task handle.

2

Configure the FreeRTOS tick timer rate

Add a macro definition to set the FreeRTOS tick rate to 1000 Hz by defining configTICK_RATE_HZ as 1000 before including FreeRTOS headers.

FreeRTOS

#define configTICK_RATE_HZ 1000
// Your code here

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

void Task1(void *pvParameters) {
    while(1) {
        printf("Task 1 is running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

void Task2(void *pvParameters) {
    while(1) {
        printf("Task 2 is running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

int main(void) {
    xTaskCreate(Task1, "Task1", configMINIMAL_STACK_SIZE, NULL, 1, NULL);
    xTaskCreate(Task2, "Task2", configMINIMAL_STACK_SIZE, NULL, 1, NULL);
    return 0;
}

Need a hint?

Define configTICK_RATE_HZ before including FreeRTOS headers to set the tick timer frequency.

3

Start the FreeRTOS scheduler

Add a call to vTaskStartScheduler() in main() after creating the tasks to start the FreeRTOS scheduler and begin task switching.

FreeRTOS

#define configTICK_RATE_HZ 1000

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

void Task1(void *pvParameters) {
    while(1) {
        printf("Task 1 is running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

void Task2(void *pvParameters) {
    while(1) {
        printf("Task 2 is running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

int main(void) {
    xTaskCreate(Task1, "Task1", configMINIMAL_STACK_SIZE, NULL, 1, NULL);
    xTaskCreate(Task2, "Task2", configMINIMAL_STACK_SIZE, NULL, 1, NULL);
    // Start the scheduler here
    return 0;
}

Need a hint?

Call vTaskStartScheduler() after creating tasks to start the FreeRTOS scheduler.

4

Run and observe task switching output

Run the program and observe the output. It should print alternating messages from Task 1 is running and Task 2 is running every second.

FreeRTOS

#define configTICK_RATE_HZ 1000

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

void Task1(void *pvParameters) {
    while(1) {
        printf("Task 1 is running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

void Task2(void *pvParameters) {
    while(1) {
        printf("Task 2 is running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

int main(void) {
    xTaskCreate(Task1, "Task1", configMINIMAL_STACK_SIZE, NULL, 1, NULL);
    xTaskCreate(Task2, "Task2", configMINIMAL_STACK_SIZE, NULL, 1, NULL);
    vTaskStartScheduler();
    // Observe output
}

Need a hint?

Run the program on a FreeRTOS-supported environment or simulator to see the alternating task messages every second.