Hello I'm trying to use the Arduino DUE in an UDOO QUAD in solo mode, without regard of the Linux. I have problems with the serial communication in only one direction, from the PC to the Arduino DUE/UDOO. The communication from Arduino DUE/UDOO to the external PC works fine and I can read the data in the Serial Monitor or with Matlab without any problem. I tested my code with an Arduino MEGA and with a standard Arduino DUE and it works in both directions: from PC to Arduino, and from Arduino to PC. The same sketch doesn't work in the UDOO's Arduino DUE. The peculiar thing is that uploading from the PC to the CN6 works fine. The UDOObuntu works fine also. Any ideas? Thanks. Equipment: -UDOO Quad with 12 V power supply. -Micro USB cable in CN6 port to PC. -SD card with Udoobuntu-udoo-qdl-desktop_2.1 -PC with Ubuntu 16.04