Hardware requirements

  • Micro USB cable

  • EVK-MIMXRT685 board

  • Personal Computer

Board settings

MCUBoot layout

Region

From

To

Size

MCUboot code

0x80000000

0x8003FFFF

256kB

Primary slot

0x80040000

0x8023FFFF

2048kB

Secondary slot

0x80240000

0x8043FFFF

2048kB

  • MCUBoot header size is set to 1024 bytes

  • Signing algorithm is RSA-2048

  • Write alignment is 4 bytes

  • MCUBoot is configured to use its DIRECT_XIP image handling strategy

  • Flash remapping HW feature is used for zero-overhead image swapping

Image signing example

imgtool sign   --key sign-rsa2048-priv.pem
               --align 4
               --version 1.1
               --slot-size 0x200000
               --header-size 0x400
               --pad-header
               ota_mcuboot_basic.bin
               ota_mcuboot_basic.SIGNED.bin

Note that for the first image flashed manually together with the bootloader additional imgtool options “–pad” and “–confirm” must be used. Otherwise the bootloader would reject the image for missing data in the trailer area.