Impact on Secure Serial DFU if there is change in Flash and Ram address

RE: Impact on Secure Serial DFU if there is change in Flash and Ram address

beemavishnu — Fri, 07 Aug 2020 18:38:09 GMT

Than a lot for correcting me.

RE: Impact on Secure Serial DFU if there is change in Flash and Ram address

Hung Bui — Fri, 07 Aug 2020 14:58:06 GMT

I believe Bjørn meant FLASH_START + FLASH_SIZE <= the Bootloader start address,

It can be 0xD1000 if you don't have any application data, but if you want to reserve 3 pages for that you need to take that into account , so the correct flash size is 0xCE000.

RE: Impact on Secure Serial DFU if there is change in Flash and Ram address

beemavishnu — Fri, 07 Aug 2020 09:32:55 GMT

Thank you.

Reason behind change FLASH_SIZE=0xd1000 is because of below my other query link.

https://devzone.nordicsemi.com/f/nordic-q-a/61106/analyzing-flash_start-ram_start-and-corresponding-linker-macros

"Yes, you need to set the FLASH_SIZE in the application so that FLASH_START + FLASH_SIZE => the Bootloader start address, otherwise you risk overwritting the bootloader."

Thanks & Regards

Vishnu Beema

RE: Impact on Secure Serial DFU if there is change in Flash and Ram address

Hung Bui — Fri, 07 Aug 2020 09:19:23 GMT

Hi Vishnu,

You can have a look at the memory layout here: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.0/lib_bootloader.html?cp=7_1_3_5_0_7#lib_bootloader_memory

Usually the bootloader for S140 nRF52840 is located at 0xF8000 (unless you change this). If you have 3 reserved applicatoin pages =12kB, then the space left for application is

0xF8000 - 0x3000 - 0x27000 = 0xCE000.

Note that if you use more than half of the application flash space you can't do dual bank DFU update and need to do single bank update (erase old application before receiving new application)

RE: Impact on Secure Serial DFU if there is change in Flash and Ram address

beemavishnu — Thu, 06 Aug 2020 12:13:22 GMT

Hi,

Thank you for your inputs.

Yes we are using bootloader. Can you please let me know any macro which indicate maximum flash size.

In our application, we are using FDS_VIRTUAL_PAGES as 3. If FDS_VIRTUAL_PAGES macro is changed, we will make sure it is same even in Bootloader macro NRF_DFU_APP_DATA_AREA_SIZE, so that FDS_VIRTUAL_PAGES = (NRF_DFU_APP_DATA_AREA_SIZE / (1024 * 4) = 3

Thanks & Regards

Vishnu Beema

RE: Impact on Secure Serial DFU if there is change in Flash and Ram address

Hung Bui — Thu, 06 Aug 2020 11:54:36 GMT

Hei Vishnu,
The RAM modification wouldn't have anything to do with the DFU because the application won't run at the same time as the bootloader.
Regarding the FLASH modification , so in your application you reduce the Flash size ? Do you have any reason to do so ?
Changing that wouldn't affect the DFU process neither, but I'm not very certain why you want to change the flash size.

Note that if you plan to have the bootloader you need to recalculate the maximum flash size to avoid that the application area overlap the bootloader area.