vTaskDelay() for periodic tasks in FreeRTOS - Mini Project: Build & Apply

Using vTaskDelay() for Periodic Tasks in FreeRTOS

📖 Scenario: You are working on a simple embedded system using FreeRTOS. You want to create a task that prints a message every 1 second to simulate a periodic sensor reading.

🎯 Goal: Build a FreeRTOS task that uses vTaskDelay() to run periodically every 1 second and prints a message each time it runs.

📋 What You'll Learn

Create a task function named vPeriodicTask.

Use vTaskDelay() inside the task to wait for 1 second between prints.

Create the task in main() with a stack size of 100 and priority 1.

Print the message "Task running" each time the task runs.

💡 Why This Matters

🌍 Real World

Periodic tasks are common in embedded systems to read sensors, update displays, or communicate regularly.

💼 Career

Understanding how to use FreeRTOS task delays is essential for embedded software engineers working on real-time applications.

1

Create the periodic task function

Write a task function called vPeriodicTask that takes a void *pvParameters argument. Inside the function, write an infinite loop using for(;;). Inside the loop, print the message "Task running". Do not add any delay yet.

FreeRTOS

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

void vPeriodicTask(void *pvParameters) {
    // Your code here
}

int main(void) {
    // Your code here
    return 0;
}

Need a hint?

Remember to use for(;;) for an infinite loop and printf to print the message.

2

Add delay using vTaskDelay()

Inside the infinite loop of vPeriodicTask, after the printf statement, add a call to vTaskDelay() to delay the task for 1000 milliseconds (1 second). Use pdMS_TO_TICKS(1000) to convert milliseconds to ticks.

FreeRTOS

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

void vPeriodicTask(void *pvParameters) {
    for(;;) {
        printf("Task running\n");
        // Your code here
    }
}

int main(void) {
    // Your code here
    return 0;
}

Need a hint?

Use vTaskDelay(pdMS_TO_TICKS(1000)) to delay for 1 second inside the loop.

3

Create the task in main()

In main(), create the task vPeriodicTask using xTaskCreate(). Use a stack size of 100, priority 1, and pass NULL for parameters and task handle. Then start the scheduler with vTaskStartScheduler().

FreeRTOS

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

void vPeriodicTask(void *pvParameters) {
    for(;;) {
        printf("Task running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

int main(void) {
    // Your code here
    return 0;
}

Need a hint?

Use xTaskCreate() with the correct parameters and then call vTaskStartScheduler().

4

Run and observe the periodic output

Run the program and observe the output. The program should print Task running every 1 second repeatedly.

FreeRTOS

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

void vPeriodicTask(void *pvParameters) {
    for(;;) {
        printf("Task running\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

int main(void) {
    xTaskCreate(vPeriodicTask, "PeriodicTask", 100, NULL, 1, NULL);
    vTaskStartScheduler();
    // Your code here
    return 0;
}

Need a hint?

You should see the message Task running printed every second repeatedly.