Serial debug problem


I am using Arduino Duemilanove on Ubuntu 9.10 with IDE version 0017. All was well until three days ago. Since then if I change the serial debug baud rate in the serial debug window to anything higher than 9600 I lose communications with the comm port (error opening serial port 'dev/ttyUSB0'). Once that occurs the comm port is unavailable, Serial Port is grayed out under Tools, and I can no longer upload any sketch or monitor serial output. I can put any serial rate I want in the sketch but if it is not 9600 or lower I have no debug capability.

Once this occurs to get back to being able to upload a sketch I must do this: close the IDE and either delete the ~/.arduino/preferences.txt file in its entirety or delete the line in that file that sets the serial debug rate (serial.debug_rate=xxxxx) Simply closing the IDE does not help and plugging/unplugging the device does not help. When I reopen the IDE I can upload sketches fine. I can also monitor serial debug output as long as the rate set in the sketch is 9600 or less. If I use the IDE but do not try to change the serial debug rate then all is well and on subsequent restarts of the IDE I do not have to delete anything in the preferences.txt file.

I can't point to any major system changes that could account for this. It was working fine then seems to have just happened. I reinstalled java and the ide but to no avail. Dmesg looks good for the ftdi and it does work unless I use the serial debug at more than 9600.

Any ideas??

Thanks all.

Do you experience the same issue without the IDE? Could you try to connect to the Arduino with some skript or some terminal program (like putty)? If so: does the issue arise there as well?

I took Mr. Klein's suggestion and connected to the Arduino directly via a linux tty, not through the IDE. I did not have any problems sending or receiving data using any baud rate.

However when I went back to using the IDE after doing this I discovered I no longer had the problem I reported previously. For whatever reason the problem is resolved and I can change baud rate with the IDE without any issue now.

I can only surmise that elves came in and fixed it. I wish they would leave a note for future reference.

I can only surmise that elves came in and fixed it.

Busy little buggers on the forum, aren't they?

It has to do with Quantum Compudynamics. See here
and here
Connecting through the Linux tty is a source of Computrons and a drain of Bogons. Once the balance shifts back to the Bogons you should again connect through the Linux tty which should then in turn fix it for some time :slight_smile: