Migrate STM32F4 Bare-Metal Firmware to FreeRTOS: UART & I2C Guide

Introduction

This tutorial will guide you through the migration of bare-metal firmware for the STM32F4 microcontroller to FreeRTOS. We will implement two tasks: one for UART communication and another for I2C interaction. This step-by-step process ensures your firmware can leverage the features of FreeRTOS for better task management.

Prerequisites

• Basic knowledge of C programming and embedded systems
• STM32F4 development board
• STM32CubeIDE or any compatible IDE
• FreeRTOS kernel files
• Familiarity with UART and I2C communication protocols

Parts/Tools

• STM32F4 Development Board
• USB to UART converter (if needed)
• Jumper wires for I2C connections
• STM32CubeMX for generating initialization code
• FreeRTOS source files

Steps

1. Set Up FreeRTOS in Your Project
   1. Download the FreeRTOS kernel from the official website.
   2. Extract the files and add them to your STM32CubeIDE project.
   3. Include FreeRTOS headers in your main source file:

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

2. Configure STM32CubeMX
   1. Open STM32CubeMX and create a new project for your STM32F4 board.
   2. Enable UART and I2C peripherals in the Pinout & Configuration tab.
   3. In the Configuration tab, set the parameters for UART and I2C as needed.
   4. Go to the Middleware section and enable FreeRTOS.
   5. Generate the initialization code.
3. Create UART Task
   1. In your main.c file, create a function for the UART task:

   void UART_Task(void *pvParameters) {
       while(1) {
           // Code to handle UART communication
       }
   }

   2. Create the task in the main function:

   xTaskCreate(UART_Task, "UART_Task", 128, NULL, 2, NULL);

4. Create I2C Task
   1. Similarly, create a function for the I2C task:

   void I2C_Task(void *pvParameters) {
       while(1) {
           // Code to handle I2C communication
       }
   }

   2. Implement the task in the main function:

   xTaskCreate(I2C_Task, "I2C_Task", 128, NULL, 2, NULL);

5. Initialize UART and I2C
   1. In the main function, after FreeRTOS initialization, call the HAL initialization functions:

   HAL_UART_Init(&huart1);
   HAL_I2C_Init(&hi2c1);

6. Start the Scheduler
   1. At the end of your main function, start the FreeRTOS scheduler:

   vTaskStartScheduler();

Troubleshooting

If you encounter issues during the migration, consider the following:

• Check Peripheral Initialization: Ensure that UART and I2C are properly initialized before their respective tasks start.
• Task Stack Size: If tasks are not executing as expected, increase the stack size during task creation.
• Priorities: Adjust the task priorities to ensure critical tasks have higher priority.
• Debugging: Use debug prints within tasks to verify their execution and flow.

Conclusion

By following this tutorial, you have successfully migrated your STM32F4 bare-metal firmware to FreeRTOS with implemented UART and I2C tasks. FreeRTOS allows for better task management and efficient resource utilization, making it a great choice for embedded system applications. Continue to explore FreeRTOS features such as queues and semaphores to further enhance your project.