+# Input clock frequency.\r
+# This will define a symbol, F_CLOCK, in all source code files equal to the \r
+# input clock frequency (before any prescaling is performed). This value may\r
+# differ from F_CPU if prescaling is used on the latter, and is required as the\r
+# raw input clock is fed directly to the PLL sections of the AVR for high speed\r
+# clock generation for the USB and other AVR subsections. Do NOT tack on a 'UL'\r
+# at the end, this will be done automatically to create a 32-bit value in your\r
+# source code.\r
+#\r
+# If no clock division is performed on the input clock inside the AVR (via the\r
+# CPU clock adjust registers or the clock division fuses), this will be equal to F_CPU.\r
+F_CLOCK = 8000000\r
+\r
+\r