Not able to enter DFU mode of nRF52840 Fanstel dongle after upgraded the bootloader compiled from secure_bootloader example

[Yuriy Sharamaha]

I had to upgrade SoftDevice and application firmware from v6.1.1 to v7.2.0 in order to have BLE_GATTC_OPT_UUID_DISC option available.

It turned out that Bootloader needs to be updated as well.

That's why I have generated the public/private key-pair using NrfUtil and replaced dfu_public_key.c in nRF5_SDK_17.1.0_ddde560\examples\dfu. Then I've successfully compiled nRF5_SDK_17.1.0_ddde560\examples\dfu\secure_bootloader\pca10056_usb and the bootloader hex file has been generated: nRF5_SDK_17.1.0_ddde560\examples\dfu\secure_bootloader\pca10056_usb\armgcc\_build\nrf52840_xxaa.hex.

According to Nordic Semiconductor Infocenter I've created the upgrade zip package containing bootloader which was signed by the previous private key, not the new one generated above:

nrfutil pkg generate --hw-version 52 --sd-req 0xb6 --bootloader-version 2 --bootloader nrf52840_xxaa.hex --key-file private.pem bl.zip

Then I've successfully loaded it to the dongle by: 

NrfUtil.exe dfu usb-serial -pkg bl.zip -p COM5
[####################################] 100%
Device programmed.

After that, the dongle never starts DFU mode while pressing the button during plugging it into USB port.

Is there is a way to let dongle to enter DFU mode again?

What is the correct way to upgrade SoftDevice and Bootloader from v6.1.1 to v7.2.0?

Thank you in advance!

Yuriy

[Yuriy Sharamaha]

I see, thanks for the information. I just need to program the dongle, but Reset button stopped working :( Is there any other way how to reset the dongle?

[Paul Bradford]

The subject of this case says it's about a Fanstel 52840 dongle, not the Nordic dev-dongle.

[Amanda Hsieh]

Seems my suggestions could not help the Fanstel 52840 dongle. Because it's Fanstel's product, you need to go to Fanstel for help/support with their product.

-Amanda