2 # This will define a symbol, F_CPU, in all source code files equal to the
3 # processor frequency in Hz. You can then use this symbol in your source code to
4 # calculate timings. Do NOT tack on a 'UL' at the end, this will be done
5 # automatically to create a 32-bit value in your source code.
7 # This will be an integer division of F_USB below, as it is sourced by
8 # F_USB after it has run through any CPU prescalers. Note that this value
9 # does not *change* the processor frequency - it should merely be updated to
10 # reflect the processor speed set externally so that the code can use accurate