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Update Mass Storage bootloader so that it can support devices with only 4KB bootloader sections by creating a special AUX section before the real bootloader section to store part of the bootloader code.

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Dean Camera 2013-03-18 17:18:11 +00:00
parent f8a1dc7424
commit be33d3a515
12 changed files with 136 additions and 109 deletions
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36
Bootloaders/MassStorage/BootloaderMassStorage.txt
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@ -12,6 +12,8 @@
*
* \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 Series 2 USB AVRs (AT90USBxx2, ATMEGAxxU2) - <i>See \ref SSec_Aux_Space</i>
*
* \section Sec_Info USB Information:
*
@ -49,7 +51,7 @@
* 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 8KB of bootloader space. If you wish to alter this size and/or change the AVR model, you will need to
* 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
@ -100,6 +102,22 @@
* #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.
*
@ -121,6 +139,16 @@
* | |
* | |
* | |
* | |
* +----------------------------+ 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 |
@ -138,12 +166,6 @@
* +----------------------------+ FLASHEND
* \endverbatim
*
* Bootloaders reporting a device release revision number of 1.00 or greater are bootloader API enabled. 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.
*
* \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.