Thanks for your answer.
I'm not sure to understand. I think adding this to dhcpd.conf:
Will only give the same ip address to my cubietruck if it's connected to the router through eth0 or wlan0.
What i want to do is to stream movies, with minidlna, throught ethernet when this one is plugged to my router while i'm at home.
When i'm not at home, i want my cubie turning to a hotspot and stream through wlan0, with my tablet directly connected on wlan0.
That´s why i think, br0 can allow me to connect to minidlna in anyway through eth0 or wlan0 but it's not.
I Know what i want to do but i'm not sure about the way