How to add source file in STM32CubeIDE?

Here’s how to add source files to an STM32CubeIDE project (the “right” Eclipse way), plus the common gotchas.

Add a new .c/.h file inside CubeIDE

1. In Project Explorer, expand your project.

2. Right-click the folder you want (usually Core/Src for .c and Core/Inc for .h).

3. New → Source File (for .c) or New → Header File (for .h).

4. Name it (e.g., my_driver.c / my_driver.h) → Finish.

✅ CubeIDE will automatically compile any .c file that’s inside the project tree (and not excluded).

Add an existing source file (copy into project)

Method A (recommended): Copy into the project

1. Right-click Core/Src (or your own folder like Drivers/MyLib/Src).

2. Import… → General → File System (or just drag & drop).

3. Select your file(s).

4. When prompted, choose Copy files into the workspace/project.

Method B: Drag & drop

• Drag the .c/.h into Core/Src / Core/Inc

• Choose Copy (not “Link”) unless you really want external linking.

Add a whole folder/library (clean structure)

A common structure:

• Core/Inc – your headers

• Core/Src – your sources

• Drivers/MyLib/Inc

• Drivers/MyLib/Src

Steps:

1. Right-click project → New → Folder (create Drivers/MyLib/Inc and Drivers/MyLib/Src)

2. Import/copy files into those folders.

3. Add include path (next section).

Add include paths so headers are found

If you put headers somewhere other than Core/Inc, you must add an include path:

1. Right-click project → Properties

2. C/C++ Build → Settings

3. Tool Settings → MCU GCC Compiler → Includes

4. Add your include folder, e.g.:

   • ../Drivers/MyLib/Inc

5. Apply and Close

Then rebuild.

Make sure the file is actually being compiled

If the code doesn’t link, check:

• Right-click the .c file → Resource Configurations → Exclude from Build

  • Make sure it’s NOT excluded for Debug/Release.

• The file extension is correct (.c gets compiled; .h doesn’t).

Common “it still won’t work” issues

• Wrong folder added to includes: add the folder that contains the header, not the header file itself.

• Case-sensitive paths (Linux/macOS): mylib.h ≠ MyLib.h

• Name collisions: two files with same function names cause “multiple definition” linker errors.

• C++ vs C: if you add .cpp, you may need extern "C" around STM32 HAL headers.

Quick sanity check

After building, check Console output: you should see your new file being compiled, e.g.:

• arm-none-eabi-gcc ... -c my_driver.c