Programming over Nordic Secure DFU

Nordic Secure Device Firmware Update (DFU) is made over a UART serial connection. When using the nrfutil device command, this kind of programming is available to devices with a DFU trigger interface (the nordicDfu device trait).

Note

This is the primary programming method for the nRF52840 Dongle. Programming an nRF52840 Dongle requires installing the nrf-device-lib driver.

The following procedure replaces the DFU over USB serial connection in the (legacy) nRF Util for nRF5 SDK command.

Make sure you have generated the DFU package, as described in the nRF Util for nRF5 SDK user guide section. The DFU package is required for this programming scenario. This package will be referenced as <new_firmware_filename> later in this procedure.
List the devices with a DFU trigger interface (the nordicDfu device trait) by running the following command:
```
nrfutil device list --traits nordicDfu
```
If the device does not show up with the expected trait, it might need to be put into programming mode by holding in the reset button and reconnecting the dongle to the system.
The serial number of the device will be referenced as <serial_number> in the next step.
Program new firmware to a device identified by its serial number by running the following command, with <new_firmware_filename> and <serial_number> updated accordingly:
```
nrfutil device program --firmware <new_firmware_filename> --serial-number <serial_number>
```
The device is automatically put into application mode after programming. This behavior can be controlled using the --options flag. For more information, run nrfutil device --help.