USB Serial Out connector X27 not showing as /dev/ttyUSB

Hello all,

I have Colibri Evaluation Board and VF50 processors running linux. Development system is running ubuntu 16.04 on virtual box. I am trying to do serial communication. For this I am using a USB A to USB B cable. Connected the cable on dev. system and other end to X27 connector on the eval. board. On my dev. system, I am doing ls /dev/tty* so it shows me the port as ttyUSB0 but when I am running the same command on linux angstrom, it doesn’t show any connected port. I have tried restarting both the systems but the problem is same. Just to check if the cable or the connector is fine, I started a terminal (teraterm) and gave power to the eval. board. I was able to see all the startup log. So that means everything is fine but still on the colibri board in linux it doesnt show any connected port as ttyUSB. I do not have a null modem cable so cant check with it. Anything else I am missing for this connection. Please guide.

As can be seen from the Colibri Evaluation Board schematics the X27 USB device connector routes to a FTDI USB-to-serial chip which is what shows up as ttyUSB0 on your development workstation. The target side of that FTDI chip connects to the regular Colibri UART aka ttyLP0 and has nothing to do with USB aka ttyUSB. Find some more information about UART handling on Embedded Linux here.