This error happens in the linking process, the linker can't find any files that contain these functions. This might be solved by including the files which contains the mentioned functions into the Project, an explanation of how header (.h) and source (.c) files can be added can be found in this link. If the error still remains after this, it might because some definitions are disabled in the sdk_config.h file, which may cause the functions to be "grayed out".
