RT thread quick start - experience RT thread

official account 【 Learn embedded software together 】,RTOS、Linux、C

At the beginning RT-Thread Before kernel learning , Let's experience it first RT-Thread.

To experience RT-Thread, First of all, you need to have an operating environment or an experimental environment .RT-Thread It can not only run on the actual hardware platform , It can also be run in a virtual environment .

If only to learn kernel knowledge , And cooperate with the practice experiment , Virtual environment is OK . If there is an actual hardware environment , Of course it would be better .

In the official learning materials , Two virtual environments are introduced ：

• QEMU virtual machine
• Keil Simulator

Let's experience these two environments RT-Thread function .

Then I introduced RT-Thread Basic knowledge of kernel object model architecture .

QEMU virtual machine

RT-Thread Provides QEMU Simulated ARM vexpress A9 The board level support package of the development board (BSP).

stay Windows The platform is ready to run qemu-vexpress-a9 BSP engineering , But it needs to be built first Env development environment , You can refer to ：

 RT-Thread Study -Env Development environment construction

（ remarks ： The source code version of the example here is v4.0.2）

QEMU Simulated ARM vexpress A9 The board level support package of the development board (BSP) be located RT-Thread Source code BSP In the catalog qemu-vexpress-a9 Folder , Its content is shown in the figure below ：

qemu-vexpress-a9 BSP The main documents and directories are described as follows ：

file / Catalog	describe
.vscode	vscode The configuration file
applications	User application code directory
drivers	RT-Thread The underlying drivers provided
qemu.bat	Windows Platform run script file
qemu.sh	Linux Platform run script file
qemu-dbg.bat	Windows Platform debugging script file
qemu-dbg.sh	Linux Platform debugging script file
README.md	BSP Documentation
rtconfig.h	BSP Configuration header file

Compile operation

Get into bsp\qemu-vexpress-a9 Folder , open Env Tools , Input scons Instructions , Start compilation , After successful compilation, see the following figure ：

After successful compilation , Input qemu.bat, Run the program

Env The command interface displays RT-Thread Information printed during the system process , Including initialization information and version number information .

RT-Thread Support Finsh function , Users debug and view system information , Users can use commands to operate . Input help Or press tab Key to view the commands supported by the system ：

We try to enter instructions list_thread, Displays the threads currently running on the system , And thread status and stack size ：

Finsh With automatic completion function , Enter some characters of the command , Press down Tab keyboard , Then the system will display the current input characters , Find the registered related commands from the system . This function is associated with Linux The command terminal under is very similar .

Keil Simulator

MDK-ARM Software simulation simulator in software , Fully software simulation is used to explain and execute ARM The machine instructions for , And realize some peripheral logic , So as to form a complete set of virtual hardware environment , So that users can execute the corresponding target program on the computer without the help of real hardware platform .

RT-Thread An example project is provided by the government , You can simulate STM32F103 In the software simulation environment . The project download link is as follows ( Because wechat cannot add external links , Need to copy to the browser to open )：

https://www.rt-thread.org/document/site/#/rt-thread-version/rt-thread-standard/tutorial/quick-start/stm32f103-simulator/stm32f103-simulator

When the download is complete , The unzipped directory structure is as follows ：

The file types contained in each directory are described in the following table ：

Directory name	describe
applications	RT-Thread Application files .
rt-thread	RT-Thread The source file .
- components	RT-Thread Directory of various components of the .
- include	RT-Thread The header file of the kernel .
- libcpu	Transplant codes of various chips , This includes STM32 Migration files for .
- src	RT-Thread Kernel source file .
- tools	RT-Thread Command build tool script file .
drivers	RT-Thread The driver , The bottom drivers of different platforms are implemented in detail .
Libraries	ST Of STM32 Firmware library file .
kernel-sample-0.1.0	RT-Thread Kernel routines .

double-click project.uvprojx Open the project ：

This example project , The example project implements a simulation LED Flashing function , And use RT-Thread The macro MSH_CMD_EXPORT Export an instruction led. Enter... At the control terminal led , You can run this function .

After compilation , We can go through MDK-ARM To simulate the running of RT-Thread, Here's the picture ：

Enter the simulation page , Press again F5 Began to run ; Then click the button in the toolbar , Or select... In the menu bar “View→Serial Windows→UART#1”, Open the serial port 1 window , You can see that the output of the serial port only shows RT-Thread Of LOGO, This is because the user code is empty , The simulation results are shown in the figure ：

At the prompt msh> Post input led, perform LED A function that simulates flicker ：

FinSH Console

In the above two simulation runs RT-Thread In the experiments , Both mentioned FinSH. that FinSH What is it ？

Here it is , Just a brief introduction , To reach the level of understanding . With the deepening of learning , You can study it in detail later .

FinSH yes RT-Thread Command line component of , Be similar to Linux Under the shell, It provides a set of operation interfaces for users to call on the command line , It is mainly used for debugging or viewing system information , It can use serial port 、 so 、USB And so on PC communicate .

When serial port is used to connect equipment and control terminal ,FinSH The execution flow of the command is shown in the figure ：

The user inputs a command at the control terminal , Control terminal through serial port 、 USB、 The command is transmitted to the device through the network FinSH, FinSH
Will read the device input commands , Parse and automatically scan the internal function table , Find the corresponding function name , Output the response after executing the function , Response through the original
The way back , Display the results on the control terminal .

FinSH Support auto completion 、 View historical commands and other functions , These functions can be easily used through the keys on the keyboard .

RT-Thread Source code

For the convenience of study RT-Thread, We download the standard source code . The official source code download channel is provided ：

https://www.rt-thread.org/page/download.html

When the download is complete , The source code directory is as follows （ Be careful , The source code storage path location cannot contain Chinese ）：

RT-Thread The source code directory structure is as follows ：

name	describe
BSP	Board Support Package（ Board level support package ） Migration based on various development boards
components	RT-Thread Code of each component of , for example finsh,gui etc. .
documentation	The related documents , Such as coding specification, etc
examples	Related sample code
include	RT-Thread The header file of the kernel .
libcpu	Transplant codes of various chips .
src	RT-Thread Kernel source file .
tools	RT-Thread Command build tool script file .

Kernel object model

RT-Thread The kernel is designed with object-oriented design idea , System level infrastructure is a kind of kernel object , For example, threads , Semaphore , The mutex , Timers, etc .

Kernel objects fall into two categories ： Static kernel objects and dynamic kernel objects , Static kernel objects are usually placed in RW Paragraph and ZI In the paragraph , Initialize in the program after the system starts ; Dynamic kernel objects are created from the memory heap , Then do initialization manually .

Static objects take up RAM Space , Does not depend on the memory heap manager , Memory allocation time determination . Dynamic objects depend on memory heap
Manager , Runtime request RAM Space , When an object is deleted , The amount of RAM Space is released .

About the creation of dynamic objects and static objects , It will be introduced later .

Kernel object management

RT-Thread Kernel objects include ： Threads , Semaphore , The mutex , event , mailbox , Message queues and timers , Memory pool , equipment
Drive, etc . The object container contains the information of each type of kernel object , Include object types , Size, etc .

The object container assigns a linked list to each type of kernel object , All kernel objects are linked to the linked list , Pictured RT-Thread The kernel object container and linked list of are shown in the following figure ：

Each specific kernel object and object control block , In addition to the basic structure , It also has its own extended attributes .

for example , For thread control blocks , Extend based on base class objects , Added thread state 、 Priority and other properties . These properties are not used in the operation of base class objects , Only used in thread specific operations .

From an object-oriented perspective , Each concrete object is a derivation of an abstract object , Inherits the properties of the base object , And on this basis, it extends the attributes related to itself . As shown in the figure below , Derivation and inheritance of various kernel objects ：

In the object management module , Defines a common data structure , Used to store the common attributes of various objects , Various concrete objects only need to be in
On this basis, we add some special properties of our own , Can clearly express their own characteristics .

The advantages of this design method are ：

（1） It improves the reusability and expansibility of the system , Adding new object categories is easy , You only need to inherit the properties of the common object and add less Quantity expansion is enough .

（2） Provide a unified object operation mode , It simplifies the operation of various concrete objects , Improve the reliability of the system .

OK, Come here first today , The next to continue . come on. ~

official account 【 Learn embedded software together 】, Wonderful content will be delivered first