/** \file
 *
 *  This file contains special DoxyGen information for the generation of the main page and other special
 *  documentation pages. It is not a project source file.
 */
/** \page Page_BuildSystem The LUFA Build System
 *
 *  \section Sec_BuildSystem_Overview Overview of the LUFA Build System
 *  The LUFA build system is an attempt at making a set of re-usable, modular build make files which
 *  can be referenced in a LUFA powered project, to minimize the amount of code required in an
 *  application makefile. The system is written in GNU Make, and each module is independent of
 *  one-another.
 *
 *  For details on the prerequisites needed for Linux and Windows machines to be able to use the LUFA
 *  build system, see \ref Sec_CompilingApps_Prerequisites.
 *
 *  To use a LUFA build system module, simply add an include to your project makefile. All user projects
 *  should at a minimum include \ref Page_BuildModule_CORE for base functionality:
 *  \code
 *  include $(LUFA_PATH)/Build/lufa_core.mk
 *  \endcode
 *
 *  Once included in your project makefile, the associated build module targets will be added to your
 *  project's build makefile targets automatically. To call a build target, run make {TARGET_NAME}
 *  from the command line, substituting in the appropriate target name.
 *
 *  \see \ref Sec_ConfiguringApps_AppMakefileParams for a copy of the sample LUFA project makefile.
 *
 *  Each build module may have one or more mandatory parameters (GNU Make variables) which must
 *  be supplied in the project makefile for the module to work, and one or more optional parameters which
 *  may be defined and which will assume a sensible default if not.
 *
 *  \section SSec_BuildSystem_Modules Available Modules
 *
 *  The following modules are included in this LUFA release:
 *
 *  \li \subpage Page_BuildModule_ATPROGRAM - Device Programming
 *  \li \subpage Page_BuildModule_AVRDUDE - Device Programming
 *  \li \subpage Page_BuildModule_BUILD - Compiling/Assembling/Linking
 *  \li \subpage Page_BuildModule_CORE - Core Build System Functions
 *  \li \subpage Page_BuildModule_CPPCHECK - Static Code Analysis
 *  \li \subpage Page_BuildModule_DFU - Device Programming
 *  \li \subpage Page_BuildModule_DOXYGEN - Automated Source Code Documentation
 *  \li \subpage Page_BuildModule_HID - Device Programming
 *  \li \subpage Page_BuildModule_SOURCES - LUFA Module Source Code Variables
 *
 *  If you have problems building using the LUFA build system, see \subpage Page_BuildTroubleshooting for resolution steps.
 */
 /** \page Page_BuildModule_BUILD The BUILD build module
 *
 *  The BUILD LUFA build system module, providing targets for the compilation,
 *  assembling and linking of an application from source code into binary files
 *  suitable for programming into a target device, using the GCC compiler.
 *
 *  To use this module in your application makefile, add the following code:
 *  \code
 *  include $(LUFA_PATH)/Build/lufa_build.mk
 *  \endcode
 *
 *  \section SSec_BuildModule_BUILD_Requirements Requirements
 *  This module requires the the architecture appropriate binaries of the GCC compiler are available in your
 *  system's PATH variable. The GCC compiler and associated toolchain is distributed in Atmel AVR Studio
 *  5.x and Atmel Studio 6.x installation directories, as well as in many third party distribution packages.
 *
 *  \section SSec_BuildModule_BUILD_Targets Targets
 *
 *  
 *   
 *    | BOARD* | LUFA board hardware drivers to use (see \ref Page_DeviceSupport).* | 
 *   
 *    | OPTIMIZATION* | Optimization level to use when compiling source files (see GCC manual).* | 
 *   
 *    | C_STANDARD* | Version of the C standard to apply when compiling C++ source files (see GCC manual).* | 
 *   
 *    | CPP_STANDARD* | Version of the C++ standard to apply when compiling C++ source files (see GCC manual).* | 
 *   
 *    | DEBUG_FORMAT* | Format of the debug information to embed in the generated object files (see GCC manual).* | 
 *   
 *    | DEBUG_LEVEL* | Level of the debugging information to embed in the generated object files (see GCC manual).* | 
 *   
 *    | F_CPU* | Speed of the processor CPU clock, in Hz.* | 
 *   
 *    | C_FLAGS* | Flags to pass to the C compiler only, after the automatically generated flags.* | 
 *   
 *    | CPP_FLAGS* | Flags to pass to the C++ compiler only, after the automatically generated flags.* | 
 *   
 *    | ASM_FLAGS* | Flags to pass to the assembler only, after the automatically generated flags.* | 
 *   
 *    | CC_FLAGS* | Common flags to pass to the C/C++ compiler and assembler, after the automatically generated flags.* | 
 *   
 *    | COMPILER_PATH* | Directory where the C/C++ toolchain is located, if not available in the system PATH.* | 
 *   
 *    | LD_FLAGS* | Flags to pass to the linker, after the automatically generated flags.* | 
 *   
 *    | LINKER_RELAXATIONS* | Enables or disables linker relaxations when linking the application binary. This can reduce the total size
 *        of the application by replacing full \c CALL instructions with smaller \c RCALL instructions where possible.
 *        \note On some unpatched versions of binutils, this can cause link failures in some circumstances. If you
 *              receive a link error relocation truncated to fit: R_AVR_13_PCREL, disable this setting.* | 
 *   
 *    | OBJDIR* | Directory to place the generated object and dependency files. If set to "." the same folder as the source file will be used.
 *        \note When this option is enabled, all source filenames must be unique.* | 
 *   
 *    | OBJECT_FILES* | List of additional object files that should be linked into the resulting binary.* | 
 *  
 *
 *  \section SSec_BuildModule_BUILD_ProvidedVariables Module Provided Variables
 *
 *  
 *    
 *    | Problem* | Resolution* | 
 *   
 *    | Error "relocation truncated to fit: R_AVR_13_PCREL against symbol {X}" shown when compiling.* | Try compiling with the setting LINKER_RELAXATIONS=N in your LUFA Build System 2.0 makefile, or remove the line -Wl,--relax
 *        from other makefiles. Alternatively, make sure you have the latest version of the Atmel Toolchain installed for your system.* | 
 *   
 *    | Error "error: ld terminated with signal 11 [Segmentation fault]" shown when compiling.* | Try compiling with the setting DEBUG_LEVEL=2 in your LUFA Build System 2.0 makefile, or make sure you are using binutils version 2.22 or later.* | 
 *   
 *    | Error "EMERGENCY ABORT: INFINITE RECURSION DETECTED" shown when compiling.* | Make sure you are using an up to date version of GNU Make when compiling. This error is a safety system added to the mid-level makefiles, to prevent an issue with
 *        GNU make or other variants of Make causing an infinitely recursive build.* | 
 *   
 *    | Error "Unsupported architecture "{X}"" shown when compiling.* | Ensure your makefile's ARCH setting is set to one of the architecture names (case-sensitive) supported by the version of LUFA you are compiling against.* | 
 *   
 *    | Error "Makefile {X} value not set" shown when compiling.* | The specified Makefile value was not configured in your project's makefile or on the command line, and the nominated setting is required by one or more LUFA
 *        build system modules. Define the value in your project makefile and try again.* | 
 *   
 *    | Error "Makefile {X} option cannot be blank" shown when compiling.* | The specified Makefile value was configured in your project's makefile or on the command line, but was set to an empty value. For the nominated configuration
 *        option, an empty value is not allowed. Define the nominated setting to a correct non-blank value and try again.* | 
 *   
 *    | Error "Makefile {X} option must be Y or N" shown when compiling.* | The specified Makefile value was configured in your project's makefile or on the command line, but was set to a value other than a Y (for "Yes") or "N" (for "No").
 *        This configuration option is required to be one of the aforementioned boolean values, and other values are invalid. Set this option to either Y or N and try again.* | 
 *   
 *    | Error "Unknown input source file formats: {X}" shown when compiling.* | The nominated source files, specified in your project's makefile in the SRC configuration option, has an extension that the LUFA build system does not
 *        recognise. The file extensions are case sensitive, and must be one of the supported formats (*.c, *.cpp or *.S).* | 
 *   
 *    | Error "Cannot build with OBJDIR parameter set - one or more object file name is not unique" shown when compiling.* | When a project is built with a non-empty OBJDIR object directory name set, all input source files must have unique names, excluding extension and path.
 *        This means that input files that are named identically and differ only by their path or extension are invalid when this mode is used.* | 
 *   
 *    | Error "Source file does not exist: {X}" shown when compiling.* | The nominated input source file, specified in the user project's SRC parameter, could not be found. Ensure the source file exists and the absolute or
 *        relative path given in the user project makefile is correct and try again.* | 
 *   
 *    | Error "Doxygen configuration file {X} does not exist" shown when upgrading a Doxygen configuration file.* | The nominated Doxygen configuration file, specified in the user project's DOXYGEN_CONF parameter, could not be found. Ensure the configuration file exists
 *        and the absolute or relative path given in the user project makefile is correct and try again, or run the appropriate makefile target to generate a new configuration
 *        file.* | 
 *   
 *    | Error "avr-gcc: error: unrecognized option '{X}'" shown when compiling.* | An unrecognised option was supplied to the compiler, usually in the C_FLAGS, CPP_FLAGS, ASM_FLAGS or CC_FLAGS configuration
 *        options. The nominated compiler switch may be invalid, or unsupported by the version of AVR-GCC on the host system. Remove the unrecognised flag if invalid, or
 *        upgrade to the latest AVR-GCC. If the option is a valid linker option, use the prefix "-Wl," to ensure it is passed to the linker correctly.* | 
 *   
 *    | Error "makefile:{X}: {Y}.mk: No such file or directory" shown when make is invoked.* | The path to the nominated makefile module was incorrect. This usually indicates that the makefile LUFA_PATH option is not set to a valid relative or
 *        absolute path to the LUFA library core.* | 
 *   
 *    | Error "fatal error: LUFAConfig.h: No such file or directory" shown when compiling.* | The USE_LUFA_CONFIG_HEADER compile time option was set in the user project makefile, but the user supplied LUFAConfig.h header could not be
 *        found. Ensure that the directory that contains this configuration file is correctly passed to the compiler via the -I switch in the makefile CC_FLAGS
 *        parameter.* | 
 *   
 *    | Error "ld.exe: section .apitable_trampolines loaded at {X} overlaps section .text" shown when compiling a bootloader.* | The bootloader is compiling too large for the given FLASH_SIZE_KB and BOOT_SECTION_SIZE_KB parameters set in the bootloader makefile. This
 *        usually indicates that these values are incorrect for the specified device the bootloader is targeting. If these values are correct, a newer version of the
 *        compiler may need to be used to ensure that the bootloader is built within the section size constraints of the target device.* | 
 *   
 *    | Error "unknown MCU '{X}' specified" shown when compiling.* | The specified microcontroller device model name set in the user application's makefile as the MCU parameter is incorrect, or unsupported by the
 *        version of the compiler being used. Make sure the model name is correct, or upgrade to the latest Atmel Toolchain to obtain newer device support.* | 
 *   
 *    | Error "undefined reference to `{X}'" shown when compiling.* | This is usually caused by a missing source file in the user application's SRC configuration parameter. If the indicated symbol is one from the LUFA
 *        library, you may be missing a LUFA source makefile module (see \ref Page_BuildModule_SOURCES).* | 
 *  
 *
 *  For troubleshooting other errors you encounter, please see \ref Sec_ProjectHelp.
 */