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Thread: Arduino serial port contention

  1. #1

    Default Arduino serial port contention

    I'm trying to use the Arduino package with openSUSE-11.3. This problem occurs when trying to open a serial console after having successfully uploaded a sketch to an Arduino Uno. There is a lock file created when you choose the port at launch (/dev/ttyACM0). If the serial console is opened 'before' you upload a sketch it will disappear when you upload the sketch. But now, after it disappears and you've transferred the sketch to the Arduino, if you move your pointer over the 'tools' menu item you'll see a lock file appear in '/var/lock' (LCK..ttyACM0). This file is owned by my normal user account. Trying to remove it is fruitless as it just reappears when you move the cursor back to the tools menu item. So when you look back under 'tools' the serial port (dev/ttyACM0) is not there....Gone. However, if you reset the Arduino board and loose the program you uploaded to it, then you can restart the program and you will see the port again...

    So is there some work around so I can upload a sketch with a serial statement in it and then be able to use the serial monitor ? I need to be able to do this as I am designing a large system requiring several Arduino boards to communicate with one another through serial connections.

    Thank you to anyone with help regarding this software package.

    Michael Soibelman

  2. #2

    Default Re: Arduino serial port contention

    Forgot to mention this is Arduino-0022, the latest release with an Uno board.

  3. #3
    Join Date
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    Default Re: Arduino serial port contention

    I'm going to refer you to the Arduino Forum. In particular this thread:

    Arduino Forum - Easy to "brick" Arduino Uno on Linux

    Read the posts by KHK1 and rgm. Hope that helps.

  4. #4

    Default Re: Arduino serial port contention

    No. It is NOT bricked. I can still upload to it and run the program on the board ! If I transfer a program that does not require a serial console it works fine. I can do the simple 'blink' program with an led in pins 13 and gnd at it works o.k. I can then alter the program ('sketch' in Arduino speak), compile it and transfer it to the board. It will run. I can repeat the process several times and it still works. It is only when I need to communicate with the Arduino after I transfer a sketch that the serial port problem occurs. So the Uno board is not bricked. I think some people think there board is bricked when in fact they may not be ! This is almost certain. I can not only do the simple blink test but I can also drive two motors with a program I've got. I can alter the values, recompile and transfer the modified sketches, many times in a row, and it still works. Again, this is almost certainly a 'permissions/lockfile/mystery-java-thingy(since this program uses java I thought I'd throw that in there not knowing if this might be some java security feature versus openSUSE App Armor policy or something like that)' phenomenon...

    So I reiterate: This does not seem to be a bricked Arduino chip ! I've read quite a few Arduino Forums before posting this and I'm fairly certain this is a 'software' issue. It may very well be an underlying issue with the Arduino software itself, or maybe its implementation in Linux, or perhaps a particular thing with some distributions/releases/kernels, but it does appear to be something with software. I've done numerous tests to confirm this suspicion. So I'll keep hoping to find a solution.

    P.S. I read those same forum posts as you alluded to and then did some transferring and running of several programs. This pretty much indicates the board is still good. I intentionally switched pins on the board and the accompanying program(s) to specifically test different pins (registers) on the Arduino (Atmel) chip. It seems to be fine...

  5. #5
    Join Date
    Jun 2008
    Location
    Auckland, NZ
    Posts
    10,857

    Default Re: Arduino serial port contention

    I'm not sure that you'll get the help that you need here. Its almost certainly due a quirk of the linux (cdc-acm?) driver, and the way it interacts with the software interface. To that end, there won't be an openSUSE-specific solution as such. I think you need to liaise with the Arduino developers and users for any hope of a solution here.

    Anyway, at risk of the following link being or of no value to you, I include it anyway (as it may help others searching here):

    arduino opensuse

    A blog you may already be ware of:

    Arduino Blog Blog Archive Arduino 0021 for Windows, Mac, Linux (fixes PWM bug on Uno)

    Good luck

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