Create a build environment for "C" project to dynamically select folders during compile time

You can export that particular path of the folder you want to build and supply the path to the executable. You can get further info. in this thread.

How I could add dir to $PATH in Makefile?

Or simply maintain different Makefiles to make different builds and use make -f to run that particular makefile.

I hope this is what you finally want to perform.

Typically you would define your pre-processor definitions to tell the pre-processor to include only, for instance, MICRO_CONTROLLER_1 blocks of code and ignore everything else.

Something like the following should suffice:

#if defined(MICRO_CONTROLLER_1) // Block of code that is only available to MICRO_CONTROLLER_1 #elif defined(MICRO_CONTROLLER_2) // ... // All other microcontrollers you are supporting would follow this structure. #endif 

Then you would need to define MICRO_CONTROLLER_1. If you're using an IDE for development, there is typically a project option for pre-processor directives. This is where you would define MICRO_CONTROLLER_1. You could then create different "configurations" - one for each of the microcontrollers you are targeting.

This can only work if the directories have only include files. #define is a preprocessor directive. If the directories have source files, you need to solve it at the build system layer, not the preprocessor layer.

Assuming it's just include files, you'd just #include SELECT_MICRO # "Interface.h"