SDK v17.1 nRF52840 Bootloader / App memory layout question

[davidb]

I am using nRFConnect for desktop to program bootloader / softdvice / application.

After programming the images I click the read button to see what the layout looks like - see attached image.

The right side of the display shows the NRF52_FAMILY layout.

At the top there are two small green areas.

topmost green area: FF000 - FF37F  896 bytes. Region Name: Application

next lower green area: FE000-FE37F 896 bytes. Region Name: Application

Then

next lower green area: 27000-3ABFF 80896 bytes. Region Name: Application

What are those two 896-byte areas for and why are they both the same size? Should there be two?

Linker info:

linker_section_placement_file="flash_placement.xml"
linker_section_placement_macros=
FLASH_PH_START=0x0
FLASH_PH_SIZE=0x100000
RAM_PH_START=0x20000000
RAM_PH_SIZE=0x40000
FLASH_START=0xf5000
FLASH_SIZE=0x9000
RAM_START=0x20005978
RAM_SIZE=0x3a688
linker_section_placements_segments=
FLASH1 RX 0x0 0x100000
RAM1 RWX 0x20000000 0x40000
mbr_params_page RX 0x000FE000 0x1000
bootloader_settings_page RX 0x000FF000 0x1000
uicr_bootloader_start_address RX 0x10001014 0x4
uicr_mbr_params_page RX 0x10001018 0x4

Overall does this memory layout look correct?

[Vidar Berg]

Hello,

Yes, the memory layout appears to be correct. The last 2 pages are populated by the bootloader at runtime (bootloader settings + MBR paramater storage). I.e. when the bootloader boots up for the first time, it will write data to these pages.

The default memory layout for our bootloader projects are shown here: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/lib_bootloader.html#lib_bootloader_memory

Best regards,

Vidar