A ti onda izGooglas "MPLABX unable to resolve identifier" ili "CCS C unable to resolve identifier", pa procitas sta se ljudima desava, sigurno nisi jedini koji je imao ovu gresku.
Moguce da je do pogresnog/netacnog definisanja promenljive/funkcije/itd, moguce je da nisi "ukljucio" (#include) odgovarajuci .h fajl...

Evo citat Microchip forum:
LINK
"The CCS compiler uses built in functions that are created by the compiler based on #use directives. There are no header files for those functions.

From here, to get rid of the unresolved identifiers you can do a couple different things:
1. Tools->Options->C++ Tab->Highlight Unresolved Identifiers Checkbox
2. Another option is to make a header file with forward declared versions of the functions. Note that since CCS allows function overloading, you only have to forward declare one version of the method. I actually use void function_name(); for all of the ones I use. "

hahah
tako je upravo sam hteo da odgovorim na temu, da sam našao gde je problem i ti si napisao!!!
to rešava samo do nekle problem, kada u mplabu pritisnete ctrl+ space on izbaci mogućnost da se završi neka komanda, to nije moguće ovde, zbog čega, nemam pojma !!!???