Hmm...I'm starting to think my previously proposed solution to the problem of module-wide configuration visibility may not be the most appropriate one.

The configuration information I wish to make available to both parent and sub-component software modules seems to concern adapting each module to run on a specific hardware target. Consequently, a better name for the new module-wide configuration header file may be something like target.h. It's scope might then be extended to that of the single point of entry for now project-wide configurations, each of which relating specifically to adaptation of all project code to a single hardware target.

//file target.h

#ifndef TARGET_H
#define TARGET_H

#include "AT89C51RD2.h"      // The project's only reference to such a file.

#define TARGET_CPU_XTAL      22118400

#endif

//file Sio_poll.h

#ifndef SIO_POLL_H
#define SIO_POLL_H

#include "target.h"
#include "Delay.h"

#define SIO_POLL_XTAL        TARGET_CPU_XTAL      

#endif

//file Delay.h

#ifndef DELAY_H
#define DELAY_H

#include "target.h"

#define DELAY_XTAL           TARGET_CPU_XTAL   
   
#endif

End users of a software distribution structured this way, need only make a few minor changes to a single target.h file, for the entire project to then automatically adapt itself to run on their target hardware.

Does that sound a like a more orderly solution to anyone?

Regards,
Murray R. Van Luyn.