* This parameter indicates the target AVR's input clock frequency, in Hz. This is the actual clock input, before any prescaling is performed. In the
* USB AVR architecture, the input clock before any prescaling is fed directly to the PLL subsystem, and thus the PLL is derived directly from the
* clock input. The PLL then feeds the USB and other sections of the AVR with the correct upscaled frequencies required for those sections to function.
*
* <b>Note that this value does not actually *alter* the AVR's input clock frequency</b>, it is just a way to indicate to the library the clock frequency
* of the AVR as set by the AVR's fuses. If this value does not reflect the actual running frequency of the AVR, incorrect operation of one of more
* library components will occur.
*
* \section Sec_F_CPU The F_CPU Parameter
* This parameter indicates the target AVR's master CPU clock frequency, in Hz.
*
* <b>Note that this value does not actually *alter* the AVR's CPU clock frequency</b>, it is just a way to indicate to the library the clock frequency
* of the AVR core as set by the AVR's fuses. If this value does not reflect the actual running frequency of the AVR, incorrect operation of one of more
* library components will occur.
*
* \section Sec_CDEFS The CDEFS Parameter
* 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 AVR to the current configuration - if the options are incorrect, then the demo is most likely incompatible with the chosen USB AVR
* 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 (Low or Full speed) and other LUFA configuration options can be set here - see \ref Page_TokenSummary documentation for details
* on the available LUFA compile time configuration options.
