View Full Version : FTDI USB issue on Hardy - 2nd device never shows

August 13th, 2008, 10:04 PM
FYI - I live in Monument, CO and thought I'd ask this question more "locally" instead of globally.

I have an Ubuntu 64 bit Hardy running in a VM on Fusion on my Mac. I also have 6 identical FTDI based USB devices I want to attach and talk to them.

If I attach the first device, after a bit I see a /dev/ttyUSB0 show up and the appropriate log messages showing a connection appear in the /var/log/messages. So far, so good.

When I attach the 2nd device, I never see another /dev/tty-anything show up. If I disconnect the first device, and reconnect the 2nd device, the 2nd device now shows up as /dev/ttyUSB0.

It acts like it can only recognize one of these devices at a time.

When I connect the 2nd device, there are no log messages in /var/log/messages on a physical connect or disconnect.

I've also tried another approach which is to connect the devices when the VM is not active, so the devices are recognized by Mac OS X and show up as:


Back in the Fusion VM, the VM Settings dialog will list two Future Devices USB devices and I can enable them and connect them. But the same thing happens. As soon as I enable/connect the first one through the Settings dialog of the VM, I see a /dev/ttyUSB0 show up but when I connect the 2nd one, nothing happens.

Any clues about why Ubuntu is not enumerating more than one of these FTDI devices? (And I do not see any brltty errors and just in case, I did an apt-get remove brltty, so it's not in the picture anyway.)

August 14th, 2008, 12:18 AM
When you attach the other devices, are you able to see them when you run this?
lsusb It's very rare but if they have identical id's that might cause you some grief. I've never seen this happen before though. Note:
man lsusb ...for more options to get more detail from the devices.

August 14th, 2008, 04:09 PM
lsusb only shows one device. Adding the second does not show anything new via lsusb or via the log/messages.

I know the devices are ID'd differently because when I plug them into my Mac they show up as:


If they were ID'd differently, I don't think OS X could differentiate them like this.

I have one native (non-VM) ubuntu box that I will try the same test on and see if it's possibly related to the VM vs the OS.

Any other ideas are welcome.

August 14th, 2008, 04:40 PM
I hooked this same set of USB devices to a native Ubuntu Fiesty. At first it had the typical brltty conflict with FTDI, so I corrected it by:

apt-get remove brltty

and rebooted. After that both devices showed up fine as ttyUSB0 and ttyUSB1 on that machine.

So, since I was running Hardy on the VMs that are having an issue, I don't know for sure yet whether it's a VM-related issue or wether it's Hardy vs Fiesty.

I think I'll get a copy of Fiesty on the same VMWare Fusion and see if it works for that and try to eliminate the distro as a variable.

September 6th, 2008, 04:48 AM
Yes, the Arduino site (http://www.arduino.cc/playground/Learning/Linux)
say's to remove the brltty package. Apparently it causes a problem with the ftdi chips on the Arduino's.

I wonder if your devices are Arduino AVR Microcontrollers?