Lightweight Framework Designed for Embedded Systems

Introduction to mr-library

MR framework is a lightweight framework designed specifically for embedded systems. It fully considers the resource and performance needs of embedded systems. By providing standardized device management interfaces, it greatly simplifies the difficulty of embedded application development and helps developers quickly build embedded applications.

The framework provides standardized interfaces for opening (open), closing (close), controlling (ioctl), reading (read), writing (write), etc. It decouples the application from the underlying hardware drivers. Applications do not need to understand the implementation details of the drivers.

When hardware changes, only the underlying drivers need to be adapted, and the application can seamlessly migrate to the new hardware. This greatly improves the reusability of the software and the scalability to new hardware.

Key Features

• Standardized device access interfaces
• Decoupling application and driver development
• Simplifying the development of underlying drivers and applications
• Lightweight and easy to use, low resource consumption
• Modular design, decoupled and independently developed parts, extremely low hardware migration costs
• Supports use in bare-metal environments and operating system environments

Main Components

• Device framework: provides standardized device access interfaces
• Memory management: dynamic memory management
• Tools: common data structures such as linked lists, queues, balanced trees, etc.
• Various functional components

Standardized Device Interface

All operations on the device can be implemented through the following interfaces:

Example:

struct mr_spi_dev spi_dev;

int main(void)
{
    /* Register SPI10 device (CS active low) to SPI1 bus */
    mr_spi_dev_register(&spi_dev, "spi1/spi10", 0, MR_SPI_CS_ACTIVE_LOW);

    /* Open SPI10 device under SPI1 bus */
    int ds = mr_dev_open("spi1/spi10", MR_OFLAG_RDWR);
    
    /* Send data */
    uint8_t wr_buf[] = {0x01, 0x02, 0x03, 0x04};
    mr_dev_write(ds, wr_buf, sizeof(wr_buf));
    
    /* Receive data */
    uint8_t rd_buf[4] = {0};
    mr_dev_read(ds, rd_buf, sizeof(rd_buf));
    
    /* Close device */
    mr_dev_close(ds);
}

Configuration Tool

MR provides a Kconfig visual configuration tool, allowing developers to configure without needing to delve into the source code.

Kconfig will automatically generate a configuration options interface based on the configuration file. Developers can easily select the functional components to enable and set related parameters through simple operations.

By modifying parameters, quickly trim the required functions. After configuration, the configuration file is automatically generated through a Python script.

Directory Structure

Getting Started

Configuring the Kconfig Environment

Note: Kconfig is not mandatory, but recommended (installation and configuration are very quick, and subsequent tutorials will also use Kconfig as an example).

1. Verify whether the system has the Python environment installed. Run python --version in the command line to check the Python version (since Kconfig depends on python, please install python if it is not present).

2. Use the following command in the command line to install Kconfig:

   python -m pip install windows-curses
   python -m pip install kconfiglib
   

3. Run menuconfig -h in the command line to verify whether the installation was successful.

Importing the Framework into the Project

1. Download the latest version of the source code from Gitee or Github repository to your local.

2. Import the source code into the directory where your project is located. For example, in the STM32 project:

   

3. If the chip you are using has been adapted for BSP, please refer to the configuration tutorial in the corresponding BSP to complete the BSP configuration.

4. Remove unnecessary files from the bsp, document, module directories (if GIT is not needed, you can also remove the .git file). After completion, the directory structure is as follows:

   

5. Add the files to the IDE (most IDEs can automatically recognize the files under the project path, so this step is not necessary). For example, in keil:

   

   Add all files under the source, device, and driver directories.

Configuring Menu Options

1. Open the command line tool in the mr-library directory and run menuconfig to configure the menu.

   

   Note: When adding the corresponding chip driver, Device configure and Driver configure will be displayed. For Driver configure, please refer to the tutorial under BSP.

2. Select Device configure and press enter to enter the menu, and configure the functions as needed.

   

3. After configuration is complete, press Q to exit the menu configuration interface, and press Y to save the configuration.

Generating Configuration Files

1. Open the command line tool in the mr-library directory and run python kconfig.py to automatically generate the configuration file mr_config.h.

Adding Include Paths

1. Add the include path of mr-library in the compiler, for example, in keil:

   

2. Configure automatic initialization (GCC environment), find the linking script file with the suffix .ld under your project (usually link.ld), and add the following code to the script file: Note: If you are in an environment like keil that can automatically generate linking scripts, please skip this step.

   /* mr-library auto init */
   . = ALIGN(4);
   _mr_auto_init_start = .;
   KEEP(*(SORT(.auto_init*)))
   _mr_auto_init_end = .;
   

   Example:

   

3. Configure GNU syntax. If you are using a non-GCC compiler, please enable GNU syntax. For example, in keil:

   AC5:

   

   AC6:

   

4. Include #include "include/mr_lib.h" in your project.

5. Add the mr_auto_init(); automatic initialization function in the main function.

Let’s Turn on the Light

#include "include/mr_lib.h"

/* Define LED pin (PC13)*/
#define LED_PIN_NUMBER                  45

int main(void)
{
    /* Automatic initialization */
    mr_auto_init();

    /* Open PIN device */
    int ds = mr_dev_open("pin", MR_OFLAG_RDWR);
    /* Set to LED pin */
    mr_dev_ioctl(ds, MR_CTL_PIN_SET_NUMBER, mr_make_local(int, LED_PIN_NUMBER));
    /* Set LED pin to push-pull output mode */
    mr_dev_ioctl(ds, MR_CTL_PIN_SET_MODE, mr_make_local(int, MR_PIN_MODE_OUTPUT));

    while(1)
    {
        /* Light up LED */
        mr_dev_write(ds, mr_make_local(uint8_t, MR_PIN_HIGH_LEVEL), sizeof(uint8_t));
        mr_delay_ms(500);
        mr_dev_write(ds, mr_make_local(uint8_t, MR_PIN_LOW_LEVEL), sizeof(uint8_t));
        mr_delay_ms(500);
    }
}

Hello World

#include "include/mr_lib.h"

int main(void)
{
    /* Automatic initialization */
    mr_auto_init();

    /* Open Serial-1 device */
    int ds = mr_dev_open("serial1", MR_OFLAG_RDWR);
    /* Output Hello World */
    mr_dev_write(ds, "Hello World\r\n", sizeof("Hello World\r\n"));
    
    while(1);
}

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● Column “Embedded Tools”

● Column “Embedded Development”

● Column “Keil Tutorial”

● Selected Tutorials in Embedded Column