ardupilot/Tools/ArduPPM/ATMega32U2/LUFA/ManPages/ConfiguringApps.txt

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 *
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/** \page Page_ConfiguringApps Configuring the Demos, Bootloaders and Projects
 *
 *  If the target AVR model, clock speed, board or other settings are different to the current settings, they must be changed
 *  and the project recompiled from the source code before being programmed into the AVR microcontroller. Most project
 *  configuration options are located in the "makefile" build script inside each LUFA application's folder, however some
 *  demo or application-specific configuration settings (such as the output format in the AudioOut demo) are located in the
 *  main .c source file of the project. See each project's individual documentation for application-specific configuration
 *  values.
 *
 *  Each project "makefile" contains all the script and configuration data required to compile each project. When opened with
 *  any regular basic text editor such as Notepad or WordPad (ensure that the save format is a pure ASCII text format) the
 *  build configuration settings may be altered.
 *
 *  Inside each makefile, a number of configuration variables are located, with the format "<VARIABLE NAME> = <VALUE>". For
 *  each application, the important variables which should be altered are:
 *
 *    - <b>MCU</b>, the target AVR processor.
 *    - <b>BOARD</b>, the target board hardware
 *    - <b>F_CLOCK</b>, the target raw master clock frequency, before any prescaling is performed
 *    - <b>F_CPU</b>, the target AVR CPU master clock frequency, after any prescaling
 *    - <b>CDEFS</b>, the C preprocessor defines which configure options the source code
 *    - <b>LUFA_PATH</b>, the path to the LUFA library source code
 *    - <b>LUFA_OPTS</b>, the compile time LUFA options which configure the library features
 *
 *  These values should be changed to reflect the build hardware.
 *
 *  \section Sec_MCU The MCU Parameter
 *  This parameter indicates the target AVR model for the compiled application. This should be set to the model of the target AVR
 *  (such as the AT90USB1287, or the ATMEGA32U4), in all lower-case (e.g. "at90usb1287"). Note that not all demos support all the
 *  USB AVR models, as they may make use of peripherals or modes only present in some devices.
 *
 *  For supported library AVR models, see main documentation page.
 *
 *  \section Sec_BOARD The BOARD Parameter
 *  This parameter indicates the target AVR board hardware for the compiled application. Some LUFA library drivers are board-specific,
 *  such as the LED driver, and the library needs to know the layout of the target board. If you are using one of the board models listed
 *  on the main library page, change this parameter to the board name in all UPPER-case.
 *
 *  If you are not using any board-specific drivers in the LUFA library, or you are using a custom board layout, change this to read
 *  "USER" (no quotes) instead of a standard board name. If the USER board type is selected and the application makes use of one or more
 *  board-specific hardware drivers inside the LUFA library, then the appropriate stub drives files should be copied from the /BoardStubs/
 *  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.
 *
 *  \section Sec_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.
 *
 *  <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.
 */