Boot Loader micro Executable (BLUE)

A minimalistic bootloader for the nRF52840

Features:

• TODO

Missing:

• TODO

User Guide

• load hed file onto board
• when runs for the first time:
  • LED3 is on indicating the bootloader ran
  • LED1 is on indicating the first app is running
• reset the board
  • LED3 is on indicating the bootloader ran
  • there a little delay for the bootloading to happen
  • LED2 is on indicating the second app is running
• reset the board
  • LED3 is on indicating the bootloader ran
  • no delay as the second app is already in place
  • LED2 is on indicating the second app is running
• last step repeats no matter how often you reset the board

HEX file format

See https://en.wikipedia.org/wiki/Intel_HEX

:10000000000004209D080000BB0200001502000053
:                                           start code
 10                                         length of the data field
   0000                                     address, relative to a base address [big endian]
       00                                   record type 00==data
                                                        01==end of file
                                                        02==extended segment address (up to 1MB image)
                                                        03==start segment address
                                                        04==extended linear address (32-bit addressing)
         000004209D080000BB02000015020000   data
                                         53 checksum for the record (so LSB of sum of all bytes is 00)

See blue_annotated.md for an example.