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