How do I add existing files to a newly created group in Keil u Vision 4
I use uVision 5 but I suspect the answer applies to uVision 4 as well.  I typically do not add the header files to the project although I suppose you could and it wouldn't matter.  The thing you have to do is to add the path to the header files to the project's "Include Paths" option.


In the Project menu, click "Options for (Blinky) Target..."
In the Options for Target dialog, select the "C/C++" tab.
In the "Include Paths" edit box, add the path where the header files are located.  Separate multiple paths with a semicolon.


For example, if your header files are located in a subfolder named inc relative to location of the uVision project file then add ".\inc" to the Include Paths option.