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.
I've fixed my bug !
Actually, in "system_stm32f10x.c", I uncommented "#define PLL_SOURCE_HSE" instead of "#define PLL_SOURCE_HSI" and now ITM_SendChar works properly ("printf()" still doesn't work however).