secure dfu nrf52

[Stas]

1. I went though steps point here Everything went well. We create bootloader settings hex file base on our application hex file I'm a little confusing now. Should I always create bootloader settings hex file after changing my app, because it's also probably changing? and flash bootloader.hex + bootloader_settings.hex (merged together) before flashing our app.zip package

2. Could you order my mind about using butonless DFU. I want to flash firmware from nrftoolbox(or own app base on dfu library). What should I need to change in compare with previous way with using button for enter in dfu mode. I mean should/can I use the same order:

   1. Create my secure key.pem

   2. add its public version (generated by nrfutil) into secure dfu bootloader

   3. create settings bootloader base on hex file built by experimental_ble_app_buttonless_dfu example?

   4. merge it with main bootloader hex and flash to the board

   5. generate zip from experimental_ble_app_buttonless_dfu (with my private key) and flash it via nrftoolbox_dfu?

What's the simplest way to integrate this feature (buttonless enter into dfu mode) into my app base on ble_uart example.

2.1. Can I have to feature for entering into dfu mode (with button and buttonless) just in case?

Sorry if some of my questions are too stupid, I just a newbie in this area..

[bjorn-spockeli]

Hi Stas,

Q1: No, it is only necessary to generate the settings page and merge it with the bootloader hex-file the first time you flash the bootloader, application and SoftDevice to your nRF5x device.

This will ensure that the nRF52 device to starts the application and does not stay in bootloader mode due to the valid application flag not being set and the application crc being incorrect. All subsequent updates of the application will update the bootloader settings page to the correct values corresponding to the new application image.

Q2: The easiest way is to add the buttonless feature to an application is to use the experimental_ble_app_buttonless_dfu example as a template and add in the required functions.

Q2.1: Yes, it is possible add the same switch-to-the-bootloader functionality with a button press in addition to the buttonless approach.

Best regards

Bjørn

[Stas]

Thanks for so detailed answer.