[ABANDONED] Help opening USB serial link

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  • [ABANDONED] Help opening USB serial link

    Hello,

    My goal is to talk to an ARM mmc through a J-Link Segger serial link using this command:

    Source Code

    1. python3 -m serial.tools.miniterm -e /dev/ttyUSB3 115200


    However, I get the following error message:
    No such file or directory: '/dev/ttyUSB3'If I use dmesg, I can see the Segger serial device connected to a usb port (see below):

    Source Code

    1. [159707.574338] usb 1-3: new full-speed USB device number 17 using xhci_hcd
    2. [159707.724537] usb 1-3: New USB device found, idVendor=1366, idProduct=0101, bcdDevice= 1.00
    3. [159707.724542] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
    4. [159707.724545] usb 1-3: Product: J-Link
    5. [159707.724546] usb 1-3: Manufacturer: SEGGER[159707.724548] usb 1-3: SerialNumber: 000801025943

    However, I never see anything like, "... FTDI serial link established ..."
    So it looks to me like I am connected to USB3 but that I can't open up a serial link. Also I see this:

    Source Code

    1. USER@USERdev:/dev$ ls -ld ttyU*
    2. ls: cannot access 'ttyU*': No such file or directory

    Any idea as to why I can't open up a serial link?I am running Debian 11.7

    Things I've tried:
    1) install openocd
    2) install python serial link
    3) assigned myself to the dialout group

    Thanks for any help :thumbup: :thumbup: 8o
    __________________

    It's better to add by zero then multiply by it...

  • It’s pretty simple to answer why you cannot connect to the virtual COM port of J-Link:
    Because yours is not configured to expose one…
    (I can see that from the ProductID it enumerates with)

    See here:
    wiki.segger.com/Using_J-Link_VCOM_functionality
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.

  • Thank you for your assessment Alex.

    I am a newbie.

    Maybe I am using the wrong terminology. But in the past, I have used this J-Link device to communicate with my Arm mmc with what I believe was UART over usb (Isn't this called a serial connection?).
    I did this on a RHEL9 machine but now I would like to use the J-Link UART on my Debian laptop. What search terms should I be using to try to replicate the thing that I was able to do before?

    Thank you for your help,
    James
    __________________

    It's better to add by zero then multiply by it...

  • Hi James,
    VCOM (virtual COM port) is what is used to use J-Link as a virtual com port device.
    This makes it possible to use the related J-Link pins to be used as UART interface.

    The article Alex linked should do exactly what you require:
    Show J-Link as a COM port device, which can then be used by what ever application you are using to send/receive UART information
    between your PC and your target chip.

    For further information please refer to:
    wiki.segger.com/J-Link_Virtual_COM_Port
    For information about how to set it up under Linux, please refer to the article Alex already linked:
    wiki.segger.com/Using_J-Link_VCOM_functionality

    BR
    Fabian
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.

  • Newbie or not:
    Did you actually check the link I sent or did you choose to ignore it?

    As I wrote:
    Your J-Link is not configured to expose a virtual COM port but the article describes how to configure it accordingly.

    If you have *really* been using exactly this J-Link before, you either did not use virtual COM port or disabled the virtual COM port of J-Link afterwards.
    So something about your statement of using it previously is either incomplete or incorrect.
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.