The Applications of RT-Thread RTOS

Introduction

The user application is the application layer of RT-Thread RTOS. The developer can develop his/her application out of RT-Thread RTOS firmware environment.

There are two mode for RT-Thread Applications,

• Standalone Application
• Shared Library

The standalone application has a main() function as the program entry. It more like a program in the PC/Linux.

The shared library is compose of functions, and provide these APIs to other programs.

Build Application

First of all, these programs must base on RT-Thread RTOS environment, and run inside. In the RT-Thread RTOS, the module option must be enable in rtconfig.h File:

#define RT_USING_MODULE

And provide the flags for Application building in rtconfig.py file (since RT-Thread 2.1.x, these flags will be gradually added to each BSP):

• M_CFLAGS - User Application C/C++ compiler flags
• M_LFLAGS - User Application link flags

And Provide the ENV variable BSP_ROOT which points to your board support package directory.

Windows:

set BSP_ROOT=your_bsp_directory

Linux:

export BSP_ROOT=your_bsp_directory

And to run the command under your BSP directory:

scons --target=ua -s

To generate the information for User Application, such as the header file search path, the macro defined in the RT-Thread RTOS etc.

Finally, you can build the user application in rtthread-apps directory, for example:

scons --app=hello

To build hello program.

scons --lib=libtar

To build a shared library.

A Simple Application

This is a simple application of Hello World:

#include <stdio.h>

int main(int argc, char **argv)
{
    printf("Hello World!\n");
    return 0;
}

It's just like the Hello World program in the PC/Linux. Beside that, the user application can use the most of APIs of RT-Thread, for example:

#include <rtthread.h>

void my_thread_entry(void* parameter)
{
    int index;
    
    while (1)
    {
        rt_kprintf("index => %d\n", index ++);
        rt_thread_delay(RT_TICK_PER_SECOND);
    }
}

int my_thread_init(void)
{
    rt_thread_t tid;
    
    tid = rt_thread_create("tMyTask', my_thread_entry, RT_NULL, 
        2048, 20, 20);
    if (tid != RT_NULL) rt_thread_startup(tid);
    
    return 0;
}

This example will create a sub-thread, which named as 'tMyTask'.

Build the POSIX application in the host

If you didn't set RTT_ROOT/BSP_ROOT, The command scons --app=hello will build the program in host environment, for example, build it as a Linux program.

Therefore, only POSIX application can be built like that.

License

All of user application are standalone program, if there is no special explanation, the license of these program is GPLv2. While the license of RT-Thread RTOS is GPLv2+.