Build flags STM32

Hi all.

platform = ststm32
board = genericSTM32F103C8
framework = arduino

Is there a list or describtion on how to use build flags in PIO;
Just for an eksample these lines:

-DENABLE_HWSERIAL3
-DPIN_SERIAL3_RX=PB11
-DPIN_SERIAL3_TX=PB10

Where do I find the text/options written after the -D ??
I have looked in the UM1850 doc. and also stm32duino/wiki without much luck

Thanks in advance.
Jens J.

build_flags doc. There is no “list of what build flags are valid”, since that isn’t PlatformIO terroritory, but rather the code / framework’s territory.

“ENABLE_HWSERIAL3” is described in their wiki

If in doubt, look into the source code of STM32Duino itself and you will find it.

“that isn’t PlatformIO terroritory, but rather the code / framework’s territory” Arrrgh same failure as last time I asked a question, Sorry for that, I have now became a member of the STM32duino forum :slightly_smiling_face:
But I can see, that if I have to trawl many of the core files, then I have no or very small chances to find these defines.
It could be great, if it was possible to import the CubeMX files to PIO :slightly_smiling_face: :+1: I have done that with the Blink sketch, with some copy and paste, but I don’t know what to do if I have to make chances in the CubeMX files, but thats another story.
Big thank you very much for taking your time to help.
Best regards.
JJ