Complete Guide to STM32 ARM Development on Visual Studio Code

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1 Introduction

Visual Studio Code was a great contribution to the coding world. From thousands of plugins, themes and its great IntelliSense, it is a great cross-platform code editor to work with. However, to embedded projects for microcontrollers like those generated to STM32 ARM Cortex MCUs, it's important to know everything that must be configured to the development and debugging of a project.

Therefore, for this article, I'll explain all the steps required for this matter. I'm going to assume that you already have your code structured and a Makefile ready, generated whether by the STM32CubeMX initialisation code generator or downloaded from your MCU's respective website. More information on the official website.

For this tutorial, I'll be using the STM32 Nucleo-F101RB development board with a STM32F103RB microcontroller. I'll also be working on Windows, which requires some additional steps to set things up. All the differences between Linux and Windows will be addressed throughout the article.

2 Installations

Everything that must be installed is listed below.

            • Visual Studio Code
            • C/C++ Plugin
            • Cortex Debug Plugin
            • ARM GCC Compiler
            • STM32 ST-LINK Utility
            • MinGW / MSYS2 (Windows)
            • OpenOCD
                    
2.1 Visual Studio Code

The protagonist of this story, Visual Studio Code (from now on called vscode) can be downloaded here.

2.2 Plugins

After installing vscode, open it and, in the Extensions tab on the left bar (Ctrl+Shift+X), search for C/C++ and install it, or download it from vscode's marketplace here. This plugin offers language support for C/C++ to Visual Studio Code, including features such as IntelliSense and debugging.

However, we'll be using the Cortex-Debug plugin for debugging. On the same Extensions bar, search for Cortex-Debug and install it. You can also download it from the market place here.

2.3 ARM GCC Compiler

Download the ARM compiler here and install it. During installation, some necessary drivers will be installed. In the end, don't forget to select the option to add it to the PATH variable.

For Ubuntu, I recommend you to download it from the same website linked above for Windows since the recent repository version does not come with the arm-none-eabi-gdb debugger program which will be necessary for debugging.

2.4 ST-LINK Utility

STM32 ST-LINK Utility is a full-featured software interface for programming STM32 microcontrollers. It provides an easy-to-use and efficient environment for reading, writing and verifying a memory device. It will be especially necessary to program the chip. I've written an article about this process on Ubuntu that you can check out here.

Basically, to install it on Ubuntu, just type on your terminal

sudo apt install st-utils

You can download the Windows version here. It consists of a graphical user interface (GUI) with a command line interface (CLI).

I'll come back on how to prepare your Makfile latter on this article.

2.5 MinGW / MSYS2

MinGW is a minimalist development environment for native Windows applications. It will be necessary if you are using Windows like me, since it provides a GCC compiler and more importantly a command line interpreter system (MSYS), which will be useful to compile Makefiles. Download the most recent version here. After installing it, the MinGW Installation Manager will open, and you'll be able to select the packages you want to install. Select both packages as shown in the figure below.

Click on Installation on the menu bar on the top of the window and Apply Changes.

In order to debug your code, you'll need the software OpenOCD. To install it on Windows, MSYS2 is necessary. MSYS2 is, at its core, an independent rewrite of MSYS, based on modern Cygwin and MinGW-w64. It features the package management system Pacman, to provide easy installation of packages. Download it here and install it.

After closing the installer, the MSYS2 terminal will open. Run the following command multiple times until there are no more updates. You'll need to close the terminal. To reopen it, you can find it in its installation folder at C:\msys64\msys2.exe.

pacman -Syuu
2.6 OpenOCD

Finally, the last software to install is OpenOCD. The Open On-Chip Debugger is essential to debug our code. Installing it on Ubuntu is as simple as typing on your terminal

sudo apt install openocd

For Windows, open the MSYS2 terminal and type

pacman -S mingw-w64-x86_64-toolchain

3 Include Paths and Defines

For this section I'll explain how to configure the paths and defines of the project on vscode. Below, you can see the structure of my project folder. Again, the code was generated with the STM32CubeMX software.



                    

Open your project folder on vscode. By opening a file, like your main.c, you'll notice that there'll be a lot of include errors. By default, vscode will search recursively over all the folders inside the one you opened your project. Since all API drivers files are inside those folders, everything should've worked just fine. However, some defines must be passed to C/C++ plugin's configuration. Those defines can be found inside your Makefile, since they're also passed to the compiler.

Open C/C++ plugin's configuration by pressing Ctrl+Shift+P and searching for Edit Configurations (JSON). A JSON file called c_cpp_properties will open inside the new folder called .vscode created on your project's root.

Open your Makefile and look for a variable called C_DEFS like shown below.


                        # C defines
                        C_DEFS =  \
                        -DUSE_FULL_LL_DRIVER \
                        -DHSE_VALUE=8000000 \
                        -DHSE_STARTUP_TIMEOUT=100 \
                        -DLSE_STARTUP_TIMEOUT=5000 \
                        -DLSE_VALUE=32768 \
                        -DHSI_VALUE=8000000 \
                        -DLSI_VALUE=40000 \
                        -DVDD_VALUE=3300 \
                        -DPREFETCH_ENABLE=1 \
                        -DSTM32F103xB
                    

We are interested in two defines here: the first and the last one. The first one tells the compiler that we are using the low level API library. The last one indicates the which microcontroller we're using. If you chose to generate your code using the HAL library for drivers, the first will mention HAL instead.

Back in the JSON configuration file, remove everything that is currently in the defines tag and copy the ones that we'll use without the -D. Your file should look like this


                            {
                              "configurations": [
                                {
                                  "name": "Win32",
                                  "includePath": [
                                    "${workspaceFolder}/**"
                                  ],
                                  "defines": [
                                    "USE_FULL_LL_DRIVER",
                                    "STM32F103xB"
                                  ],
                                  "cStandard": "c11",
                                  "intelliSenseMode": "msvc-x64"
                                }
                              ],
                              "version": 4
                            }
                    

Close vscode and reopen it. Everything should now be fine and all include errors are gone.

4 Compiling and Flashing

As mentioned earlier, I made an article about compiling and flashing code to STM32 on Linux (Ubuntu) that you can check out here to understand what must be configured on your Makefile and how to do it using st-link utils.

Basically, if you're using Ubuntu, just add the following lines to the end of your Makefile


                        flash:
                            st-flash write $(BUILD_DIR)/$(TARGET).bin 0x8000000
                    

And for Windows


                        flash:
                            st-link_cli -me
                            st-link_cli -P $(BUILD_DIR)/$(TARGET).bin 0x8000000 -V "after_programming"
                    

Now, after compiling, you can flash the code by simple typing make flash on the terminal or command line on the project's root. This will erase the flash memory and program the chip from the memory position 0x8000000.

5 Debugging

To configure the debugging, open the debug tab on the left bar on vscode (Ctrl+Shift+D). Since there is no configuration yet, we'll customize Run and Debug by creating a launch.json file. After clicking on this option, you'll see some environments to choose. Select Cortex-Debug. The file will be created in the .vscode folder and opened.

The configuration varies depending on the microcontroller and board you're using. As I mentioned before, I'm using the STM32 Nucleo-F101RB development board with a STM32F103RB microcontroller. My configuration is as follows



                    

It's important to change the executable tag to point to your project's .elf file. The servertype tag must be setted as openocd and the device and configFiles according to your microcontroller and board. You can look for more information on the Cortex-Debug plugin's website.

It's important to note that what's in the configFiles tag is the path to the .cfg file that will be passed to OpenOCD. With OpenOCD installation, some config files from some generic boards are also installed, but you can always create your own. You can have more information on OpenOCD's Guide Line.

Now you can finally head back to the Run and Debug tab and start debugging. If you get and OpenOCD error, it's probably because whether the debugger can't find your OpenOCD executable or your ARM GDB path. To fix it, create a file called settings.json inside your .vscode folder (if it doesn't already exist) with the following instructions to the Cortex-Debug plugin, adjusting the paths if it's the case.


                        {
                            "cortex-debug.armToolchainPath": "C:/Program Files (x86)/GNU Tools Arm Embedded/9 2019-q4-major/bin",
                            "cortex-debug.openocdPath": "C:/msys64/mingw64/bin/openocd.exe"
                        }
                    

6 Conclusion

Well, that's it. I think I've explained all the steps required to work with STM32 (compile and debug) using Visual Studio Code, whether you're using Linux or Windows. We have seen how to install all the softwares required, set up the Makefile to compile and flash the code and finally how to debug.

This has been a long article to write and I hope I have covered everything in a clear and understandable way. If you have any problems with the whole process or something to add, let me know through the comments section below.

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