Duemilanove not accessible on Ubuntu 10.04 if atta

Hello everyone,

I have a very strange problem. I’m using a Duemilanove to send serial data to a Ubuntu 10.04 system. I start Ubuntu, plug in the controller, open a console and type “screen /dev/ttyUSB0 9600” and everything is working as expected. I can see the data.

Then I shutdown the Ubuntu PC and switch the power of. The controller is still connected to the PC. I restart the PC and type “screen /dev/ttyUSB0 9600” again and it tells me that it can not open /dev/ttyUSB0. Disconnecting the controller and connecting it again and everything is working.

I have removed brltty, but this does not help.
So my question is: what is using/blocking /dev/ttyUSB0 if the device is attached during boot.

Thanks in advance

Dierk

When the USB is not working what does dmesg | grep ttyUSB0 show you?

dmesg | grep ttyUSB0 shows

[ 15.076835] usb 3-4: FTDI USB Serial Device converter now attached tp ttyUSB0

I think the problem is not that ttyUSB0 is not there, it is. The problem is that it seemed to be used by another process/application. But this happens only if the Arduino is attached during the boot process. Again, if I disconnect the Arduino, wait 3 seconds and attach it again, then it works.

If I use an UNO, which uses /dev/ttyACM0, it works in both cases.

If I use IDE 0018 (on Windows) to flash the Duemilanove, everything is working as expected, even if the Duemilanove is attached at startup.

I am using Ubuntu 10.04 64bit as well… anyway, I am wondering if pressing reset button does the same trick for you?

What I have noticed is that once a while Ubuntu assigns ttyUSB1 to the Arduino board if it thinks something is using the ttyUSB0 board could you try dmesg | grep ttyUSB to see how many ttyUSB devices are there when this happens next time?