I have build and flashed the zephire/sample/bluetooth/hci_uart on nrf52840 board and connected the board with ubuntu but hci interface was not created when checked using hciconfig.
Can you please provide the steps for the same . I have used below step
cd zephyr/samples/bluetooth/hci_uart
mkdir nrf_build
cmake -DBOARD=nrf52840_pca10056 ../
make
make flash
hciconfig
But no hci interface created