Background DFU questions

[mosgaard2000]

Hi,

I am implementing a background DFU bootloader and uses the example from Vidar Berg (https://devzone.nordicsemi.com/f/nordic-q-a/46994/background-dfu-application-source-code?ReplySortBy=CreatedDate&ReplySortOrder=Ascending).

So far everything is running fine on my nRF52840DK.

My next step is to build the bootloader with our own private/public keys. In Vidars example he uses a hex file with merged BL+SD (bootloader_w_softdevice_nrf52840.hex).

My question is which bootloader has he used. The example code includes a  project "examples\dfu\secure_bootloader\pca_10056_usb\", but is this the project to use or is it "examples\iot\bootloader"?

[Simonr]

Hi Morten

I asked Vidar, and he's almost certain that he used serial bootloader with USB for this project. There should not be very many changes necessary to make it support background DFU. Just a few flags need to be set in sdk_config.h

Best regards,

Simon

[mosgaard2000]

Thank you.

I actually tested some more and this is what I found out:

1) There is a bootloader_w_softdevice.hex which is 479KB. I get the same size if I merge SD and BL (from IOT example).

2) There is a bootloader_w_softdevice_nrf52840.hex which is 522KB. I get that size if I merge SD and BL (from DFU example)

In my test project both files actually works, but I seem to recall (from another thread I can't find again) that the nRF52840 had some special working conditions or bugs or something.

So do I need to use the DFU example when working with nRF52840 or is it because I then both enable background DFU but also have the option to run BLE, USB DFU at the same time?

[Simonr]

mosgaard2000 said:

So do I need to use the DFU example when working with nRF52840 or is it because I then both enable background DFU but also have the option to run BLE, USB DFU at the same time?

 I'd suggest using the DFU example in order to be sure that background DFU is enabled, and because I'm not 100% sure what this IOT example is/does.

Best regards,

Simon

[mosgaard2000]

I ended up using the IOT example - that works just as well.