X-Git-Url: http://git.linex4red.de/pub/lufa.git/blobdiff_plain/fa456ce531b75e2dd3c7c0ecb971e3ede36f5d35..99145a8d7c88d9af065cfb7f5e8507d5b65ff811:/LUFA/GettingStarted.txt?ds=inline diff --git a/LUFA/GettingStarted.txt b/LUFA/GettingStarted.txt index 0fe3f50b9..a88a82533 100644 --- a/LUFA/GettingStarted.txt +++ b/LUFA/GettingStarted.txt @@ -57,14 +57,22 @@ * directory into a /Board/ folder inside the application directory, and the stub driver completed with the appropriate code to drive the * custom board's hardware. * - * \subsection SSec_F_CPU The F_CPU Parameter - * This parameter indicates the target AVR's master clock frequency, in Hz. Consult your AVR model's datasheet for allowable clock frequencies - * if the USB interface is to be operational. + * \subsection SSec_F_CLOCK The F_CLOCK Parameter + * 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. * - * Note that this value does not actually *alter* the AVR's clock frequency, it is just a way to indicate to the library the clock frequency + * Note that this value does not actually *alter* the AVR's input clock frequency, 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 ocurr. * + * \subsection SSec_F_CPU The F_CPU Parameter + * This parameter indicates the target AVR's master CPU clock frequency, in Hz. + * + * Note that this value does not actually *alter* the AVR's CPU clock frequency, 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 ocurr. + * * \subsection SSec_CDEFS The CDEFS Parameter * 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 seperate lines.