Currently the Arduino API answer
No device found on ttyACM0
But I'm sure the ATSAM is working ( because I can program it with USB port)
And I have tried the UART communication ( With an oscilloscope) and I have seen that ATmega16u2 send data but ATSAM do not respond.
And after sending caracters throught UART communication from ATSAM to ATmega16u2, I have verify the TX pin of ATSAM so why the bootloader do not respond to the programmer?