Development tools for Zephyr on STM32Workbench for Zephyr: VS Code extension to set up, build, flash and debug Zephyr applications on STM32.Devicetree manager: browse, edit and visualize Zephyr devicetree, STM32CubeMX-like for Zephyr.
Dora
Research on the internet - Calling C functions from C++ code.
This sounds like its your problem.
You need to wrap your C function declarations in:
extern "C" ;