* This is due to two reasons; one, it is the hardware the author posesses, and two, it is the most popular Atmel\r
* USB demonstration board to date.\r
*\r
+ *\r
* \section Sec_Prerequisites Prerequisites\r
* Before you can compile any of the LUFA library code or demos, you will need a recent distribution of avr-libc (1.6.2+)\r
* and the AVR-GCC (4.2+) compiler. For Windows users, the best way to obtain these is the WinAVR project\r
* (http://winavr.sourceforge.net) as this provides a single-file setup for everything required to compile your\r
* own AVR projects.\r
*\r
+ *\r
* \section Sec_Configuring Configuring the Demos, Bootloaders and Projects\r
* If the target AVR model, clock speed, board or other settings are different to the current settings, they must be changed\r
* and the project recompiled from the source code before being programmed into the AVR microcontroller. Most project\r
*\r
* - <b>MCU</b>, the target AVR processor.\r
* - <b>BOARD</b>, the target board hardware\r
- * - <b>F_CPU</b>, the target AVR master clock frequency\r
+ * - <b>F_CLOCK</b>, the target raw master clock frequency, before any prescaling is performed\r
+ * - <b>F_CPU</b>, the target AVR CPU master clock frequency, after any prescaling\r
* - <b>CDEFS</b>, the C preprocessor defines which configure the source code\r
*\r
* These values should be changed to reflect the build hardware.\r
* directory into a /Board/ folder inside the application directory, and the stub driver completed with the appropriate code to drive the\r
* custom board's hardware.\r
*\r
- * \subsection SSec_F_CPU The F_CPU Parameter\r
- * This parameter indicates the target AVR's master clock frequency, in Hz. Consult your AVR model's datasheet for allowable clock frequencies\r
- * if the USB interface is to be operational.\r
+ * \subsection SSec_F_CLOCK The F_CLOCK Parameter\r
+ * 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\r
+ * 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\r
+ * 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.\r
*\r
- * <b>Note that this value does not actually *alter* the AVR's clock frequency</b>, it is just a way to indicate to the library the clock frequency\r
+ * <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\r
* 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\r
* library components will ocurr.\r
*\r
+ * \subsection SSec_F_CPU The F_CPU Parameter\r
+ * This parameter indicates the target AVR's master CPU clock frequency, in Hz.\r
+ *\r
+ * <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\r
+ * 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\r
+ * library components will ocurr.\r
+ *\r
* \subsection SSec_CDEFS The CDEFS Parameter\r
* Most applications will actually have multiple CDEF lines, which are concatenated together with the "+=" operator. This ensures that large\r
* numbers of configuration options remain readable by splitting up groups of options into seperate lines.\r
* interface speed (Low or Full speed) and other LUFA configuration options can be set here - refer to the library documentation for details on the\r
* configuration parameters.\r
*\r
+ *\r
* \section Sec_Compiling Compiling a LUFA Application\r
* Compiling the LUFA demos, applications and/or bootloaders is very simple. LUFA comes with makefile scripts for\r
* each individual demo, bootloader and project folder, as well as scripts in the /Demos/, /Bootloaders/, /Projects/\r
* in AVRStudio, the project can be built and cleaned using the GUI buttons or menus. Note that the AVRStudio project files make\r
* use of the external project makefile, thus the procedure for configuring a demo remains the same regardless of the build environment.\r
*\r
+ *\r
* \section Sec_Programming Programming a USB AVR\r
* Once you have built an application, you will need a way to program in the resulting ".HEX" file (and, if your\r
* application uses EEPROM variables with initial values, also a ".EEP" file) into your USB AVR. Normally, the\r
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