STM32CubeMX

Code generation rules (IMPORTANT)

Do not write custom code in CubeMX-generated files. CubeMX will overwrite generated files during regeneration. Any custom code placed there will be lost, even if it appears to work temporarily.

Rule:

• Generated code is read-only.
• Your code lives outside of it.

What to do instead:

• Put all application logic in your own source files (src/, modules, drivers, etc.).
• Only use generated code as initialization and hardware configuration.
• Call your own code from the appropriate entry points (e.g. after init in main()).

Bottom line:
If your code depends on surviving a “Generate Code” click, it’s in the wrong place.