1.8.3 USB Host MSD Bootloader Configurations

Bootloader Specific User Configurations

fs_bootloader_mcc_config_usb

  • Bootloader Media Type:

    • Change the Media Type to USB Mass Storage Device

  • Bootloader NVM Memory Used:

    • Specifies the memory peripheral used by bootloader to perform flash operations

    • The name of the peripheral will vary from device to device

  • Bootloader Size (Bytes):

    • Specifies the maximum size of flash required by the bootloader

    • This size is calculated based on Bootloader type and Memory used

    • This size will vary from device to device and should always be aligned to device erase unit size

  • Enable Bootloader Trigger From Firmware:

    • This Option can be used to Force Trigger bootloader from application firmware after a soft reset. It does so by reserving the specified number of bytes in SRAM from the start of the RAM. The reserved memory is updated by the application with a pre-defined pattern. The bootloader firmware in the bootloader_Trigger() routine, can check the reserved memory for the pre-defined pattern and enter bootloader mode if the pattern matches.

    • Number Of Bytes To Reserve From Start Of RAM:

      • This option adds the provided offset to RAM Start address in bootloader linker script.

      • Application firmware can store some pattern in the reserved bytes region from RAM start for bootloader to check at reset in bootloader_Trigger() function

  • Application Binary Image Path:

    • Application binary image file name with path. If only file name is mentioned bootloader will try to open the file from the root directory

    • Default: image.bin

    • Can be used to specify custom paths based on requirement

      • Example: dir1/dir2/app.bin

File System Configurations

fs_bootloader_mcc_config_usb_fs

  • Use File System Auto Mount Feature:

    • Enabled by default when File System Bootloader is added

  • Media Type:

    • Change the Media Type to SYS_FS_MEDIA_TYPE_MSD

  • Make FAT File System Read-only:

    • Enabled by default when File System Bootloader is added as there are no write operations to be done

    • Enabling this option also saves significant amount of flash memory

Bootloader System Configurations

fs_bootloader_mcc_config_usb_system

  • Application Start Address (Hex):

    • Start address of the application which will programmed by bootloader

    • This value is filled by bootloader when its loaded which is equal to the bootloader size. It can be modified as per user need

    • This value will be used by bootloader to Jump to application at device reset

Bootloader Linker Pre Processor Macros for CORTEX-M based MCUs

  • Based on the configurations the above linker pre processor macros will be generated in MPLAB X xc32-ld settings

    • ROM_LENGTH specifies the size of the bootloader

fs_bootloader_usb_linker_setting