DFU over BLE using slots on external flash

[Sankton]

Hello Hi Greetings 
This Ticket is regarding documentation and configuration on DFU over BLE using slots on external flash.


We are using 52833soc based custom board that has SPI flash .
We thought that suppose the new firmware upgrade won't have enough memory in soc flash to store , so we thought we can use external flash to store new firmware image and then do the swapping .


I am here to seek direction . 
Please can you tell me a flowchart like how I should approach this task .
like first I think I should study boot loaders and see what's MCUboot and what's nrf's secure boot .

I feel a flowchart / numbered points from a specialist will help more , that raising tickets all the time . So please help me with this , like what should be done first like partitioning or setting up MCUboot .

After that please provide me the link of sample example (if its there ) that does this operation .

Thanks 

S

[Amanda Hsieh]

Hi, 

like first I think I should study boot loaders and see what's MCUboot and what's nrf's secure boot .

 See the Quick start guide and this Bootloaders and DFU/FOTA course. 

Please can you tell me a flowchart like how I should approach this task .

To update via BLE DFU with SPI external flash on nRF52833, you should make sure the SPI external flash works as expected at first. Here is a sample. You can take a look at the settings: nrf52840dk_nrf52840_spi.conf and nrf52840dk_nrf52840_spi.overlay and adopt them for your nRF52833 custom board. 

Then, To use the SPI external flash as the second slot, it needs:

• Enable mcuboot, you can use sysbuild_fota.conf to include sysbuild configs. 
• These external SPI settings are for the app configuration. 
• The board overlay file looks like this for the app. 
• These external SPI setting (under sysbuild/mcuboot) are for the mcuboot.
• The board overlay file looks like this for the mcuboot.  

Before you start the work, I highly recommend you take a look at the Bootloaders and DFU/FOTA course to know how the mcuboot and DFU work in the NCS, and use nRF52840DK to familiarize yourself with the flow and setting, then move to your custom board.  

Regards,
Amanda H.

[Sankton]

Hi Amanda Hsieh 

My question now is when we create separate partition for secondary slot in external flash , do I have to explicitly write new image on secondary slot using write_spi api's or MCUboot bootloader does that for me ?

[Amanda Hsieh]

The mcuboot would do that. 

[Sankton]

also sysbuild_fota.conf & other overlay(https://github.com/nrfconnect/sdk-nrf/blob/v2.7.0/applications/nrf5340_audio/sysbuild/mcuboot/prj_fota.conf#L48-L56) you mentioned this file I have to Create separately in child_image/mcuboot/boards right ?

I don't see any sysbuild folder in my example code of "spi flash"
also im done with setting up spi flash and it worked well , thank you 

[Sankton]

hi Amanda Hsieh 
I finally did all steps you mentioned above with all configuration settings and overlay and I got no errors , now can you tell me next steps like how to initiate the communication (BLE) stack to test this OTA DFU .

[Sankton]

also I can detect the external flash in my partition now , hope this is correct 

[Amanda Hsieh]

The memory layout seems the external flash setting is correct.  

Sankton said:

can you tell me next steps like how to initiate the communication (BLE) stack to test this OTA DFU .

I highly recommend you take a look at the Bootloaders and DFU/FOTA course to know how the mcuboot and DFU work—especially, Exercise 3 – FOTA over Bluetooth Low Energy.

I see you are using v2.4.0 toolchain to compile v2.3.0 SDK. What NCS version would you use? If possible, I suggest moving to the latest SDK for bug fixing. From v2.7.0, The previous method to define multi-image builds (parent-child images) is deprecated and being replaced by Sysbuild (System build). 

[Sankton]

HI Amanda Hsieh 

The partition you saw above in screenshot , just declares and initialises external flash partition , I don't see partitions "within" external flash , that mcuBOOT may comprehend that the secondary slot exist at external flash not SoC flash .

I have followed all configuration as you said 
Also I don't see sdk 2.7.0 yet in my vscode 

following is my mcuboot conf

[Sankton]

Also I have gone thru the devzone course , there they use ncs example config option to support dfu which I can’t use . So that’s why looking for alternative 

[Amanda Hsieh]

You can take a look at the SMP server sample. 

[Sankton]

Hi Amanda Hsieh 
Greetings of the Day 
I performed the DFU update after implementing SMP server for my test application , I can see the Nordic Application on my mobile connecting to my custom board , and I have DFU option enabled , when I uploaded a signed binary with a customisation -> UPLOAD ONLY , which I infer means that the new firmware will just be written to secondary slot .

My secondary slot as per all configuration should exist in External Flash as we discussed . Following is my  Partition manager  report 

Amanda I expect my new firmware to be written by mcuBOOT to this secondary slot in external flash at address 0x71000 right ? ( as per your messages above you said that I won't have to explicitly write new firmware image to the external flash )

Or at 0x74000 . im not sure about this , but partition in my overlay file starts at 0x71000.



I tried to read my external flash after I uploaded my new firmware image with customisation in nrf connect app  -> UPLOAD ONLY 


my logs below 



After DFU (upload only performed )




I read at multiple offset mentioned above but I found all data to be 0xFF , 

Please let me know where I might be lagging . 

A direction can help me be better engineer , looking forward your expertise here Amanda 
Thanks 

S

[Amanda Hsieh]

Did you upload a new image with any changes? Without changes, the image would not be uploaded and updated. 

Are you able to upload a new image via the nRF Device app without issue? If so, Are you able to see it boot up with the new image after updating?