53.1.3 Fuse Configurations

  • The Bootloader has the Fuse settings set to default except below fuse bits
    • The Bootloader region size (4096 Bytes) is specified using the BOOTPROT fuse bit. BOOTPROT = 0x10.
    • The Bootloader region is protected by setting the SULCK configuration at production to 0x6 (SULCK.BS = 0).
  • The Fuse settings can be changed in following ways:
    • The Bootloader provides a separate command to program the Fuse Bits received from the host. Refer to the Bootloader protocol documentation and respective host utility documentation for more information.
    • The application can check the Fuse bits during the boot-up, then program any change required using the NVMCTRL peripheral.
  • Fuse settings are placed in a higher memory location in the Flash (User Row and BOCOR Row). The Fuse settings need to be disabled for the application project, which will be boot-loaded, as the size of the binary file becomes too large when the fuse settings are enabled.
  • When updating the Bootloader itself, make sure that the fuse settings for the Bootloader application are also disabled.
  • For PIC32CM LS00/LS60:
    • Proper fuse settings required by the application have to be sent along with application binary.
    • Peripherals used by the Bootloader (SERCOM5, SERCOM2, BOOT Pin) should not be configured as Non-Secure while updating the Fuse settings.
    • When WDT is enabled from the Fuse Settings, the bootloader refreshes the WDT at intervals to avoid reset. Therefore, the WDT peripheral should not be configured as Non-Secure if it is enabled through Fuse settings.