Macro Callbacks is a term defined in PSoC Creator to call user code from macros specified in a Component's generated code. These macros can be used by defining them in the user-defined header file named cyapicallbacks.h. This file will be included in all generated source files that offer callbacks.
A callback requires you to complete the following:
To complete the example, the cyapicallbacks.h file would include this code:
void SimpleComp_1_Start_Callback( void );
In any other user file, you could include cyapicallbacks.h and write the SimpleComp_1_Start_Callback() function.
This forum link may be useful in the requirement: