Hi,

In Keil C, how do I conditionally only declare a SFR in circumstances where it has not previously been declared?

I tried the following, but it appears that previous declarations of the CKCON SFR are not recognised as a 'definition', hence the compiler flags a redefinition error:

/*
 * Clock control register declaration (for when available and not previously declared).
 */
#ifndef CKCON
    sfr CKCON = 0x8F;
#endif

Any clues on how this might be achieved would be sincerely appreciated.

Regards,
Murray R. Van Luyn.