Create RT thread software simulation project and write RT thread kernel

newly build RT-Thread engineering —— Software emulation

At the beginning of writing RT-Thread Before the kernel , So let's just create a new one RT-Thread engineering ,Device choice Cortex-M3（Cortex-M4 or Cortex-M7） The processor of the kernel , Select software simulation for debugging mode , Finally, put RT-Thread Migration to STM32 Development board . The final migration is very simple , Just change the startup file and add bsp Just drive .

New local project folder
Before starting the new project , Let's create a new folder in the local computer to store the project . You can name the folder “ newly build RT-Thread engineering —— Software emulation ”（ The name can be set at will ）, Then create new folders and files under this folder , The inclusion relations and functions of these folders are shown in the table 1 Shown .

surface 1 Folders under the root directory of project folders and their functions

Use KEIL New project

New Project

Start by opening KEIL5 Software , Build a new project , The project files are placed in the newly created directory Project below , Name it RT-Thread-ra, among ra Is custom , It should be noted that it must be in English , Not in Chinese .

Select Device for Target

Set the project name , After confirmation, the corresponding... Will pop up Select Device for Target Dialog box , Select processor , Choose here ARMCM4, Can also be based on Device Model selection ARMCM3 or ARMCM7, Choose according to your own development board

Manage Run-Time Environment

After selecting the processor , single click OK The button will pop up Manage Run-Time Environment Dialog box . Here it is CMSIS Column CORE, stay Device Column Startup File can

single click OK Button , close Manage Run-Time Environment After the dialog , Just selected CORE and Startup These two files will be added to the project group

These two files were initially stored in KEIL Installation directory , When configuring Manage Run-Time Environment After the dialog , The software will transfer the selected file from KEIL Copy the installation directory of to our project directory Project\RTE\Device\（ARMCM3ARMCM4 or ARMCM7） below . among startup_ARMCM4.s Is a startup file written in assembly language ,system_ARMCM4.c Yes, it is C Language and clock related files . Want to know more specific content , You can read the source code of these two files directly . As long as it is （Cortex-M3、Cortex-M4 or Cortex-M7） The single chip microcomputer of the kernel , Both documents apply .

stay KEIL Create a new file group in the project

Create an empty main.c

Set up software emulation

No development board can use this software to simulate

Modify clock size

In the clock related file system_ARMCM4.c The beginning of , There is a code that defines the frequency of the system clock as 25MHz. In software simulation , Make sure the time is accurate , The system clock in the code must be consistent with the clock in the software simulation , therefore Options for Target In the dialog box Target The clock frequency in the tab should be set by default 12 Change to 25.

 Clock related macro definitions 
#define __HSI　　　　　　( 8000000UL)
#define __XTAL　　　　　 ( 5000000UL)

#define __SYSTEM_CLOCK　　(5*__XTAL) /* 5*5000000=25M*/

Add the header file path

Reference resources 《RT-Thread Kernel Implementation and application development practice guide -STM32》