I am using ISE tool for implementing my design.But i am facing a problem.In this tool it is written that some modules are supported to infer rather than inatantiate. My prof says to make design wholly structural . and using the modules available, just like we do in shematic. But since for some design elements , instatiating is not supported, i cant do it.I have to write a module code to infer that module.but according to prof this should not be the way.
Second thing while making these design elements (like counter) with flip flop and gates (for which instantiation is supported), its min clock period is large compared to the one which is inferred.Suggest me what can do here.
Third in case of inferring the element is mapped to some Macros and LUT.Can someone please explain me give some reference , what is phisically these are and to what hardware they are actually mapped.