* This parameter indicates the raw input clock frequency to the USB module within the microcontroller in Hz. This may be very different on some platforms
* to the main CPU clock or other peripheral/bus clocks.
* Many applications have features which can be controlled by the defining of specially named preprocessor tokens at the point of compilation - for example,
* an application might use a compile time token to turn on or off optional or mutually exclusive portions of code. Preprocessor tokens can be
* defined here by listing each one with the -D command line switch, and each token can optionally be defined to a specific value. When defined in the
* project makefile, these behave as if they were defined in every source file via a normal preprocessor define statement.
*
* Most applications will actually have multiple CDEF lines, which are concatenated together with the "+=" operator. This ensures that large
* numbers of configuration options remain readable by splitting up groups of options into separate lines.
*
* \section Sec_LUFA_PATH The LUFA_PATH Parameter
* As each LUFA program requires the LUFA library source code to compile correctly, the application must know where the LUFA library is located. This
* value specifies the path to the LUFA library base relative to the path of the project makefile.
*
* \section Sec_LUFA_OPTS The LUFA_OPTS Parameter
* This value is similar to the CDEFS parameter listed elsewhere -- indeed, it is simply a convenient place to group LUFA related tokens away from the
* application's compile time tokens. Normally, these options do not need to be altered to allow an application to compile and run correctly on a
* different board or microcontroller to the current configuration - if the options are incorrect, then the demo is most likely incompatible with the chosen
* microcontroller model and cannot be made to function through the altering of the makefile settings alone (or at all). Settings such as the USB mode
* (device, host or both), the USB interface speed and other LUFA configuration options can be set here - see \ref Page_TokenSummary documentation for details