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qmk_firmware/Bootloaders/MassStorage/BootloaderMassStorage.txt
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/** \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.
*/
/** \mainpage Mass Storage Class USB AVR Bootloader
*
* \section Sec_Compat Demo Compatibility:
*
* The following list indicates what microcontrollers are compatible with this demo.
*
* \li Series 7 USB AVRs (AT90USBxxx7)
* \li Series 6 USB AVRs (AT90USBxxx6)
* \li Series 4 USB AVRs (ATMEGAxxU4) - <i>See \ref SSec_Aux_Space</i>
* \li ATMEGA32U2 - <i>See \ref SSec_Aux_Space</i>
*
* \section Sec_Info USB Information:
*
* The following table gives a rundown of the USB utilization of this demo.
*
* <table>
* <tr>
* <td><b>USB Mode:</b></td>
* <td>Device</td>
* </tr>
* <tr>
* <td><b>USB Class:</b></td>
* <td>Mass Storage Device</td>
* </tr>
* <tr>
* <td><b>USB Subclass:</b></td>
* <td>Bulk-Only Transport</td>
* </tr>
* <tr>
* <td><b>Relevant Standards:</b></td>
* <td>USBIF Mass Storage Standard \n
* USB Bulk-Only Transport Standard \n
* SCSI Primary Commands Specification \n
* SCSI Block Commands Specification</td>
* </tr>
* <tr>
* <td><b>Supported USB Speeds:</b></td>
* <td>Full Speed Mode</td>
* </tr>
* </table>
*
* \section Sec_Description Project Description:
*
* This bootloader enumerates to the host as a Mass Storage device, capable of reading and writing a new binary
* firmware image file, to load firmware onto the AVR.
*
* Out of the box this bootloader builds for the AT90USB1287 with an 8KB bootloader section size, and will fit
* into 6KB of bootloader space. If you wish to alter this size and/or change the AVR model, you will need to
* edit the MCU, FLASH_SIZE_KB and BOOT_SECTION_SIZE_KB values in the accompanying makefile.
*
* When the bootloader is running, the board's LED(s) will flash at regular intervals to distinguish the
* bootloader from the normal user application.
*
* \warning <b>THIS BOOTLOADER IS NOT SECURE.</b> Malicious entities can recover written data, even if the device
* lockbits are set.
*
* \section Sec_Running Running the Bootloader
*
* On the USB AVR8 devices, setting the \c HWBE device fuse will cause the bootloader to run if the \c HWB pin of
* the AVR is grounded when the device is reset.
*
* The are two behaviours of this bootloader, depending on the device's fuses:
*
* <b>If the device's BOOTRST fuse is set</b>, the bootloader will run any time the system is reset from
* the external reset pin, unless no valid user application has been loaded. To initiate the bootloader, the
* device's external reset pin should be grounded momentarily.
*
* <b>If the device's BOOTRST fuse is not set</b>, the bootloader will run only if initiated via a software
* jump, or if the \c HWB pin was low during the last device reset (if the \c HWBE fuse is set).
*
* For board specific exceptions to the above, see below.
*
* \subsection SSec_XPLAIN Atmel Xplain Board
* Ground the USB AVR JTAG's \c TCK pin to ground when powering on the board to start the bootloader. This assumes the
* \c HWBE fuse is cleared and the \c BOOTRST fuse is set as the HWBE pin is not user accessible on this board.
*
* \subsection SSec_Leonardo Arduino Leonardo Board
* Ground \c IO13 when powering the board to start the bootloader. This assumes the \c HWBE fuse is cleared and the
* \c BOOTRST fuse is set as the HWBE pin is not user accessible on this board.
*
* \section Sec_Installation Driver Installation
*
* This bootloader uses the Mass Storage drivers inbuilt into all modern operating systems, thus no additional
* drivers need to be supplied for correct operation.
*
* \section Sec_HostApp Host Controller Application
*
* This bootloader is compatible with all operating systems that support the FAT12 file system format. To reprogram the
* device, overwrite a file stored on the virtual FAT filesystem with a new binary (BIN format) image. Remember to safely
* remove your device from the host using the host OS's ejection APIs, to ensure all data is correctly flushed to the
* bootloader's virtual filesystem and not cached in the OS's file system driver.
*
* The current device firmware can be read from the device by reading a file from the virtual FAT filesystem. Two files will
* be present:
* - <b>FLASH.BIN</b>, representing the AVR's internal flash memory
* - <b>EEPROM.BIN</b>, representing the AVR's internal EEPROM memory
*
* To convert an existing Intel HEX (.HEX) program file to a binary (.BIN) file suitable for this bootloader, run:
* \code
* avr-objcopy -O binary -R .eeprom -R .fuse -R .lock -R .signature input.hex output.bin
* \endcode
* From a terminal, replacing <tt>input.hex</tt> and <tt>output.bin</tt> with the respective input and output filenames.
* AVR EEPROM data files in Intel HEX format (.EEP) uses a similar technique:
* \code
* avr-objcopy -O binary input.eep output.bin
* \endcode
*
* \warning This bootloader is currently <b>incompatible with the Apple MacOS X OS Finder GUI</b>, due to the
* large amount of meta files this OS attempts to write to the disk along with the new binaries. On
* this platform, firmwares must be copied to the disk via the Terminal application only to prevent
* firmware corruption.
*
* \section Sec_API User Application API
*
* Several user application functions for FLASH and other special memory area manipulations are exposed by the bootloader,
* allowing the user application to call into the bootloader at runtime to read and write FLASH data.
*
* By default, the bootloader API jump table is located 32 bytes from the end of the device's FLASH memory, and follows the
* following layout:
*
* \code
* #define BOOTLOADER_API_TABLE_SIZE 32
* #define BOOTLOADER_API_TABLE_START ((FLASHEND + 1UL) - BOOTLOADER_API_TABLE_SIZE)
* #define BOOTLOADER_API_CALL(Index) (void*)((BOOTLOADER_API_TABLE_START + (Index * 2)) / 2)
*
* void (*BootloaderAPI_ErasePage)(uint32_t Address) = BOOTLOADER_API_CALL(0);
* void (*BootloaderAPI_WritePage)(uint32_t Address) = BOOTLOADER_API_CALL(1);
* void (*BootloaderAPI_FillWord)(uint32_t Address, uint16_t Word) = BOOTLOADER_API_CALL(2);
* uint8_t (*BootloaderAPI_ReadSignature)(uint16_t Address) = BOOTLOADER_API_CALL(3);
* uint8_t (*BootloaderAPI_ReadFuse)(uint16_t Address) = BOOTLOADER_API_CALL(4);
* uint8_t (*BootloaderAPI_ReadLock)(void) = BOOTLOADER_API_CALL(5);
* void (*BootloaderAPI_WriteLock)(uint8_t LockBits) = BOOTLOADER_API_CALL(6);
*
* #define BOOTLOADER_MAGIC_SIGNATURE_START (BOOTLOADER_API_TABLE_START + (BOOTLOADER_API_TABLE_SIZE - 2))
* #define BOOTLOADER_MAGIC_SIGNATURE 0xDCFB
*
* #define BOOTLOADER_CLASS_SIGNATURE_START (BOOTLOADER_API_TABLE_START + (BOOTLOADER_API_TABLE_SIZE - 4))
* #define BOOTLOADER_MASS_STORAGE_SIGNATURE 0xDF30
*
* #define BOOTLOADER_ADDRESS_START (BOOTLOADER_API_TABLE_START + (BOOTLOADER_API_TABLE_SIZE - 8))
* #define BOOTLOADER_ADDRESS_LENGTH 4
* \endcode
*
* From the application the API support of the bootloader can be detected by reading the FLASH memory bytes located at address
* \c BOOTLOADER_MAGIC_SIGNATURE_START and comparing them to the value \c BOOTLOADER_MAGIC_SIGNATURE. The class of bootloader
* can be determined by reading the FLASH memory bytes located at address \c BOOTLOADER_CLASS_SIGNATURE_START and comparing them
* to the value \c BOOTLOADER_MASS_STORAGE_SIGNATURE. The start address of the bootloader can be retrieved by reading the bytes
* of FLASH memory starting from address \c BOOTLOADER_ADDRESS_START.
*
* \subsection SSec_Aux_Space Auxiliary Bootloader Section
* To make the bootloader function on smaller devices (those with a physical bootloader section of smaller than 6KB) a second
* section of memory (called the <i>Auxiliary Bootloader Section</i>) is added before the start of the real bootloader section,
* and is filled with a portion of the bootloader code. This allows smaller devices to run the bootloader, at the cost of an
* additional portion of the device's FLASH (the bootloader section size in KB subtracted from the 6KB total size). A small
* trampoline is inserted at the start of the auxiliary section so that the bootloader will run normally in the case of a blank
* application section.
*
* On devices supporting a 8KB bootloader section size, the AUX section is not created in the final binary.
*
* \subsection SSec_API_MemLayout Device Memory Map
* The following illustration indicates the final memory map of the device when loaded with the bootloader.
*
* \verbatim
* +----------------------------+ 0x0000
* | |
* | |
* | |
* | |
* | |
* | |
* | |
* | |
* | User Application |
* | |
* | |
* | |
* | |
* | |
* | |
* | |
* | |
* +----------------------------+ FLASHEND - BOOT_SECTION_SIZE - BOOT_AUX_SECTION_SIZE
* | Booloader Start Trampoline |
* | (Not User App. Accessible) |
* +----------------------------+ FLASHEND - BOOT_SECTION_SIZE - BOOT_AUX_SECTION_SIZE + 4
* | |
* | Auxiliary Bootloader |
* | Space for Smaller Devices |
* | (Not User App. Accessible) |
* | |
* +----------------------------+ FLASHEND - BOOT_SECTION_SIZE
* | |
* | Bootloader Application |
* | (Not User App. Accessible) |
* | |
* +----------------------------+ FLASHEND - 96
* | API Table Trampolines |
* | (Not User App. Accessible) |
* +----------------------------+ FLASHEND - 32
* | Bootloader API Table |
* | (User App. Accessible) |
* +----------------------------+ FLASHEND - 8
* | Bootloader ID Constants |
* | (User App. Accessible) |
* +----------------------------+ FLASHEND
* \endverbatim
*
* \section Sec_KnownIssues Known Issues:
*
* \par In some cases, the application is not fully loaded into the device.
* Write-caching on some operating systems may interfere with the normal
* operation of the bootloader. Write caching should be disabled when using the
* Mass Storage bootloader, or the file system synced via an appropriate command
* (such as the OS's normal disk ejection command) before disconnecting the device.
*
* \section Sec_Options Project Options
*
* The following defines can be found in this demo, which can control the demo behaviour when defined, or changed in value.
*
* <table>
* <tr>
* <th><b>Define Name:</b></th>
* <th><b>Location:</b></th>
* <th><b>Description:</b></th>
* </tr>
* <tr>
* <td>NO_APP_START_ON_EJECT</td>
* <td>AppConfig.h</td>
* <td>Define to disable automatic start of the loaded application when the virtual
* Mass Storage disk is ejected on the host.</td>
* </tr>
* </table>
*/
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