thank you for your help Xray303
I learned a little bit more of the UART protocol
and it work like that.
A byte is composing with:
-first one start bit = 0
-after Data bits between 5 and 9
-then a parity bit
-finaly one stop bit = 1
the different between the DCB protocol and UART is that the start in DCB is 1 and stop Bit is 0
Do you think it's possible to change this on the Arduino UART.