PCON register is NOT bit addressable, only registers reside on addresses x0 and x8 are bit addressable. Although some compilers can use macros to do the bit manipulation; Keil complier does not support it. You need to OR in the bit you want to set or reset.
The SMOD bit at UPSD.H is disabled. When I enable it, the compiler shouts error ''PCON invalid base address''. How can I enable the SMOD bit in the UPSD.H file?. Thank you all. Kobi