Buttonless DFU custom entry

[joe.ker]

Hi,

I am using nRF52832 with NUS and buttonless DFU running well next to each other (SDK13). Instead of the standard way to jump to the bootloader (writing a 0x01 to the DFU characteristic) I would like to use a custom command via NUS. I imagine that this would be more secure, because the bootloader can then only be entered if the command is known.

To do that, I need to remove the Bluetooth part of the buttonless DFU, but still keep the part which makes the application jump to the bootloader.

Whats the best way to implement that, does anyone have an idea?

Many thanks, Josef

[Hung Bui]

Hi Josef,

To enter bootloader, you simply need to write to bootloader setting a flag

.enter_buttonless_dfu = true;

This is done in enter_bootloader() function. After that you can wait for the flash completed event to disconnect the connection and then when the connection is disconnected (BLE_GAP_EVT_DISCONNECTED) you trigger a soft reset NVIC_SystemReset(); .

UPDATE: This is only applied for SDK v12 and SDK v13 alpha.

[joe.ker]

Perfect, thanks! I am directly using the nrf_dfu_settings_write() function with .ener_buttonless_dfu instead of enter_bootloader(), like this i can remove the ble_dfu module entirely from the project.

[joe.ker]

Hi Hung, do you by any chance know if the procedure you explained one month ago is still the same with the new SDK13? I just updated and it seems some changes have been made to the experimental buttonless bootloader and it works differently now. I am still looking into it, if you could give me a kickstart it would be highly appreciated. Thanks, J

[Hung Bui]

No, it's not the same anymore. See my blog here. It's at section 2 , Appendix 1 .

[joe.ker]

Thanks a lot for the hint! I managed to manually jump from the app to the bootloader, but can not do it yet via de app, nrf connect app just stops and nrf toolbox says "Upload failed: DFU CHARACTERISTICS NOT FOUND" and also stops. Will dig deeper into that... Any ideas?

[Hung Bui]

Do you see the same thing when you test our experimental_ble_app_buttonless_dfu ?