Bootloaders/MassStorage/BootloaderMassStorage.txt

   1 /** \file
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   6
   7 /** \mainpage Mass Storage Class USB AVR Bootloader
   8  *
   9  *  \section Sec_Compat Demo Compatibility:
  10  *
  11  *  The following list indicates what microcontrollers are compatible with this demo.
  12  *
  13  *  \li Series 7 USB AVRs (AT90USBxxx7)
  14  *  \li Series 6 USB AVRs (AT90USBxxx6)
  15  *  \li Series 4 USB AVRs (ATMEGAxxU4) - <i>See \ref SSec_Aux_Space</i>
  16  *  \li ATMEGA32U2 - <i>See \ref SSec_Aux_Space</i>
  17  *
  18  *  \section Sec_Info USB Information:
  19  *
  20  *  The following table gives a rundown of the USB utilization of this demo.
  21  *
  22  *  <table>
  23  *   <tr>
  24  *    <td><b>USB Mode:</b></td>
  25  *    <td>Device</td>
  26  *   </tr>
  27  *   <tr>
  28  *    <td><b>USB Class:</b></td>
  29  *    <td>Mass Storage Device</td>
  30  *   </tr>
  31  *   <tr>
  32  *    <td><b>USB Subclass:</b></td>
  33  *    <td>Bulk-Only Transport</td>
  34  *   </tr>
  35  *   <tr>
  36  *    <td><b>Relevant Standards:</b></td>
  37  *    <td>USBIF Mass Storage Standard \n
  38  *        USB Bulk-Only Transport Standard \n
  39  *        SCSI Primary Commands Specification \n
  40  *        SCSI Block Commands Specification</td>
  41  *   </tr>
  42  *   <tr>
  43  *    <td><b>Supported USB Speeds:</b></td>
  44  *    <td>Full Speed Mode</td>
  45  *   </tr>
  46  *  </table>
  47  *
  48  *  \section Sec_Description Project Description:
  49  *
  50  *  This bootloader enumerates to the host as a Mass Storage device, capable of reading and writing a new binary
  51  *  firmware image file, to load firmware onto the AVR.
  52  *
  53  *  Out of the box this bootloader builds for the AT90USB1287 with an 8KB bootloader section size, and will fit
  54  *  into 6KB of bootloader space. If you wish to alter this size and/or change the AVR model, you will need to
  55  *  edit the MCU, FLASH_SIZE_KB and BOOT_SECTION_SIZE_KB values in the accompanying makefile.
  56  *
  57  *  When the bootloader is running, the board's LED(s) will flash at regular intervals to distinguish the
  58  *  bootloader from the normal user application.
  59  *
  60  *  \warning <b>THIS BOOTLOADER IS NOT SECURE.</b> Malicious entities can recover written data, even if the device
  61  *           lockbits are set.
  62  *
  63  *  \section Sec_Running Running the Bootloader
  64  *
  65  *  On the USB AVR8 devices, setting the \c HWBE device fuse will cause the bootloader to run if the \c HWB pin of
  66  *  the AVR is grounded when the device is reset.
  67  *
  68  *  The are two behaviours of this bootloader, depending on the device's fuses:
  69  *
  70  *  <b>If the device's BOOTRST fuse is set</b>, the bootloader will run any time the system is reset from
  71  *  the external reset pin, unless no valid user application has been loaded. To initiate the bootloader, the
  72  *  device's external reset pin should be grounded momentarily.
  73  *
  74  *  <b>If the device's BOOTRST fuse is not set</b>, the bootloader will run only if initiated via a software
  75  *  jump, or if the \c HWB pin was low during the last device reset (if the \c HWBE fuse is set).
  76  *
  77  *  For board specific exceptions to the above, see below.
  78  *
  79  *  \subsection SSec_XPLAIN Atmel Xplain Board
  80  *  Ground the USB AVR JTAG's \c TCK pin to ground when powering on the board to start the bootloader. This assumes the
  81  *  \c HWBE fuse is cleared and the \c BOOTRST fuse is set as the HWBE pin is not user accessible on this board.
  82  *
  83  *  \subsection SSec_Leonardo Arduino Leonardo Board
  84  *  Ground \c IO13 when powering the board to start the bootloader. This assumes the \c HWBE fuse is cleared and the
  85  *  \c BOOTRST fuse is set as the HWBE pin is not user accessible on this board.
  86  *
  87  *  \section Sec_Installation Driver Installation
  88  *
  89  *  This bootloader uses the Mass Storage drivers inbuilt into all modern operating systems, thus no additional
  90  *  drivers need to be supplied for correct operation.
  91  *
  92  *  \section Sec_HostApp Host Controller Application
  93  *
  94  *  This bootloader is compatible with all operating systems that support the FAT12 file system format. To reprogram the
  95  *  device, overwrite a file stored on the virtual FAT filesystem with a new binary (BIN format) image. Remember to safely
  96  *  remove your device from the host using the host OS's ejection APIs, to ensure all data is correctly flushed to the
  97  *  bootloader's virtual filesystem and not cached in the OS's file system driver.
  98  *
  99  *  The current device firmware can be read from the device by reading a file from the virtual FAT filesystem.
 100  *
 101  *  \warning This bootloader is currently <b>incompatible with the Apple MacOS X OS Finder GUI</b>, due to the
 102  *           large amount of meta files this OS attempts to write to the disk along with the new binaries. On
 103  *           this platform, firmwares must be copied to the disk via the Terminal application only to prevent
 104  *           firmware corruption.
 105  *
 106  *  \section Sec_API User Application API
 107  *
 108  *  Several user application functions for FLASH and other special memory area manipulations are exposed by the bootloader,
 109  *  allowing the user application to call into the bootloader at runtime to read and write FLASH data.
 110  *
 111  *  By default, the bootloader API jump table is located 32 bytes from the end of the device's FLASH memory, and follows the
 112  *  following layout:
 113  *
 114  *  \snippet BootloaderAPI.h User Application API
 115  *
 116  *  From the application the API support of the bootloader can be detected by reading the FLASH memory bytes located at address
 117  *  \c BOOTLOADER_MAGIC_SIGNATURE_START and comparing them to the value \c BOOTLOADER_MAGIC_SIGNATURE. The class of bootloader
 118  *  can be determined by reading the FLASH memory bytes located at address \c BOOTLOADER_CLASS_SIGNATURE_START and comparing them
 119  *  to the value \c BOOTLOADER_MASS_STORAGE_SIGNATURE. The start address of the bootloader can be retrieved by reading the bytes
 120  *  of FLASH memory starting from address \c BOOTLOADER_ADDRESS_START.
 121  *
 122  *  \subsection SSec_Aux_Space Auxiliary Bootloader Section
 123  *  To make the bootloader function on smaller devices (those with a physical bootloader section of smaller than 6KB) a second
 124  *  section of memory (called the <i>Auxiliary Bootloader Section</i>) is added before the start of the real bootloader section,
 125  *  and is filled with a portion of the bootloader code. This allows smaller devices to run the bootloader, at the cost of an
 126  *  additional portion of the device's FLASH (the bootloader section size in KB subtracted from the 6KB total size). A small
 127  *  trampoline is inserted at the start of the auxiliary section so that the bootloader will run normally in the case of a blank
 128  *  application section.
 129  *
 130  *  On devices supporting a 8KB bootloader section size, the AUX section is not created in the final binary.
 131  *
 132  *  \subsection SSec_API_MemLayout Device Memory Map
 133  *  The following illustration indicates the final memory map of the device when loaded with the bootloader.
 134  *
 135  *  \verbatim
 136  *  +----------------------------+ 0x0000
 137  *  |                            |
 138  *  |                            |
 139  *  |                            |
 140  *  |                            |
 141  *  |                            |
 142  *  |                            |
 143  *  |                            |
 144  *  |                            |
 145  *  |      User Application      |
 146  *  |                            |
 147  *  |                            |
 148  *  |                            |
 149  *  |                            |
 150  *  |                            |
 151  *  |                            |
 152  *  |                            |
 153  *  |                            |
 154  *  +----------------------------+ FLASHEND - BOOT_SECTION_SIZE - BOOT_AUX_SECTION_SIZE
 155  *  | Booloader Start Trampoline |
 156  *  | (Not User App. Accessible) |
 157  *  +----------------------------+ FLASHEND - BOOT_SECTION_SIZE - BOOT_AUX_SECTION_SIZE + 4
 158  *  |                            |
 159  *  |     Auxiliary Bootloader   |
 160  *  |  Space for Smaller Devices |
 161  *  | (Not User App. Accessible) |
 162  *  |                            |
 163  *  +----------------------------+ FLASHEND - BOOT_SECTION_SIZE
 164  *  |                            |
 165  *  |   Bootloader Application   |
 166  *  | (Not User App. Accessible) |
 167  *  |                            |
 168  *  +----------------------------+ FLASHEND - 96
 169  *  |   API Table Trampolines    |
 170  *  | (Not User App. Accessible) |
 171  *  +----------------------------+ FLASHEND - 32
 172  *  |    Bootloader API Table    |
 173  *  |   (User App. Accessible)   |
 174  *  +----------------------------+ FLASHEND - 8
 175  *  |   Bootloader ID Constants  |
 176  *  |   (User App. Accessible)   |
 177  *  +----------------------------+ FLASHEND
 178  *  \endverbatim
 179  *
 180  *  \section Sec_KnownIssues Known Issues:
 181  *
 182  *  \par In some cases, the application is not fully loaded into the device.
 183  *  Write-caching on some operating systems may interfere with the normal
 184  *  operation of the bootloader. Write caching should be disabled when using the
 185  *  Mass Storage bootloader, or the file system synced via an appropriate command
 186  *  (such as the OS's normal disk ejection command) before disconnecting the device.
 187  *
 188  *  \section Sec_Options Project Options
 189  *
 190  *  The following defines can be found in this demo, which can control the demo behaviour when defined, or changed in value.
 191  *
 192  *  <table>
 193  *   <tr>
 194  *    <th><b>Define Name:</b></th>
 195  *    <th><b>Location:</b></th>
 196  *    <th><b>Description:</b></th>
 197  *   </tr>
 198  *   <tr>
 199  *    <td>NO_APP_START_ON_EJECT</td>
 200  *    <td>AppConfig.h</td>
 201  *    <td>Define to disable automatic start of the loaded application when the virtual
 202  *        Mass Storage disk is ejected on the host.</td>
 203  *   </tr>
 204  *  </table>
 205  */
 206