I assume you are using Project Explorer and multiple c files. I think you can #include the file in a header file and #include the header file in whichever c file needs it.
The basic rules for structuring Project Explorer projects are as follows:
1) Eliminate .H files from the Project Explorer window. Instead, #include .H files as needed in the various .C files.
2) Functions, macros and typedefs (including structure typedefs) which are accessed in multiple .C files should be prototyped / defined / typedef'd in a .H file and the .H file #included by each file that accesses the function / macro / typedef. Generally, the prototype / macro / typedef would be placed in the .H file corresponding to the .C file where the function / macro / typedef is implemented / associated / instantiated.
3) Declare global variables to be extern in the appropriate .H file. If the global variable is a structure, declare the extern structure variable following the structure definition / typedef. For example, keep "bbram cfgstruct Cfg;" in main.C but put "extern bbram cfgstruct Cfg;" in main.H, following the cfgstruct typedef.
I also suggest reading any ANSI C book which discusses file scoping.