Thanks for the help Ljking.
I do not understand very well your message and for sure I miss some point and understanding.
So I appreciate your help.
1) Why should I load the Arduino code? I made one already and it is working fine. Sending data at 9600 bauds every seconds. Using an external FTDI driver this works fine. I can receive my data into a PC. But if I send the same data to the DragonBoard it is not working.
2) What code should I use for the DragonBoard? You are using Debian I am using Android. Also David is using Debian.
I already made an Android app to get the data and I also try by placing ttyHS0 with adb in "cat -v < ttyHS0" to get the data and I receive the same result on both (app and cat), receive my message + garbage.
3) I have to remove R5 because when I place the ttyHS0 in receive mode this raise RTS and reset my Arduino. The Arduino stays in reset.
4) I receive the data now that I remove R5 but I also get a lots of garbage. If I had the wrong baud rate I would receive only garbage.
5) About demo? The Debian demo, there is nothing in Android. Every one refer to Debian so far.
And at the end I am (we are) just simply trying to send data from a simple Arduino to the DragonBoard that it. And so far to me this is not working.
Maybe my board is defective?
Any other idea? And thank you for a reply.