The install directory of Arduino IDE can be found here:

• /home/\<USERNAME>/.arduino15/(Linux)
• /Users/\<USERNAME>/Library/Arduino15/(Mac)
• C:\Users\<USERNAME>\AppData\Local\Arduino15\(Windows 10 and 11)

First make sure you have installed the stm32 core using theArduino Boards Manager.

The stm32 core files can then be found in this directory:

<Arduino IDE install directory>/packages/STMicroelectronics/hardware/stm32/2.8.1.

Go to the Arduino IDE install directory. See above.

Then, go to the<Arduino install directory>/packages/STMicroelectronics/tools/STM32Tools/2.2.3 directory.