Serial communication "unstoppable" on Linux?

Forum 2005-2010 (read only) General Frequently-Asked Questions
1

Folks, I put this here since I'm not sure precisely what the problem is - if it needs to go to another board, let me know and I'll move it.

I bought myself a Uno for Christmas and am brand new to Arduino (although I have a history with Stamps.)

My main laptop is running Ubuntu 10.4 Linux. I got the Arduino working fine with this system using the instructions here: [ubuntu] Unable to get Arduino Uno working - no /dev/ttyACM0 in IDE, or so I thought.

I've run through all of the blinky LED tutorials and some others, but recently started in on serial communication. The problem I'm having is that once a sketch that involves the Uno talking "back" to the computer is running, something happens.

For example, I had a Parallax/Memsic 2-axis accelerometer and was following the tutorial/example for it in the wiki. The sketch compiles, uploads and runs fine. No problems on the hardware side, either. While I can open the serial monitor and watch the data coming in, and the TX light on the Uno stays lit, once I upload a sketch like that, I can't stop the sketch or upload anything else.

Additionally, once I disconnect the Uno, if I plug it in again, the IDE sees the port as "busy" and won't connect. I get the following error:

processing.app.SerialException: Serial port '/dev/ttyACM0' not found.  Did you select the right one from the Tools > Serial Port menu?
      at processing.app.Serial.<init>(Unknown Source)
      at processing.app.Serial.<init>(Unknown Source)
      at processing.app.debug.Uploader.flushSerialBuffer(Unknown Source)
      at processing.app.debug.AvrdudeUploader.uploadViaBootloader(Unknown Source)
      at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(Unknown Source)
      at processing.app.Sketch.upload(Unknown Source)
      at processing.app.Sketch.exportApplet(Unknown Source)
      at processing.app.Sketch.exportApplet(Unknown Source)
      at processing.app.Editor$DefaultExportHandler.run(Unknown Source)
      at java.lang.Thread.run(Thread.java:636)
processing.app.debug.RunnerException: Serial port '/dev/ttyACM0' not found.  Did you select the right one from the Tools > Serial Port menu?
      at processing.app.debug.Uploader.flushSerialBuffer(Unknown Source)
      at processing.app.debug.AvrdudeUploader.uploadViaBootloader(Unknown Source)
      at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(Unknown Source)
      at processing.app.Sketch.upload(Unknown Source)
      at processing.app.Sketch.exportApplet(Unknown Source)
      at processing.app.Sketch.exportApplet(Unknown Source)
      at processing.app.Editor$DefaultExportHandler.run(Unknown Source)
      at java.lang.Thread.run(Thread.java:636)

Various presses of the reset button don't seem to help.

The only way I can fix this at the moment is to go bother my wife and plug my Uno into the only Windows computer in the house. This is not an ideal solution.... :smiley:

Anyway, I was wondering if anyone had an idea as to what I might want to investigate?

Thanks - this is a pretty neat community here, and I hope to contribute better in the future!

Regards,

Richard Perry

2

Various presses of the reset button don't seem to help.

Try holding down RESET until the moment you are ready to upload.

I suspect you can jumper RESET to GND instead of holding the button but someone more familiar with the Uno schematic should confirm.

3

I suspect you can jumper RESET to GND instead of holding the button but someone more familiar with the Uno schematic should confirm.

Yes, save your fingertip and just use jumper (reset>gnd) and yank jumper off at just the right microsecond.

Lefty

4

You are probably hitting this problem:

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1286088093/34#34

5

for the reconnection error:
something weird is going on.(well not exactly, i think all about file descriptor)
try this: open the serial console on arduino ide, unplug and re-plug the usb, you will see arduino has changed it's path because "/dev/ttyACM0" was taken by the open console.

solution: before re-plug arduino, be sure there is no process still using ACM0, if something goes wrong you will find arduino on /dev/ttyACM1, or /dev/ttyACM2 and so on...
(well if the package you installed is not doing something weird... that's what you get if you want easy things ;D)