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how to write data to BeagleBone USB host

Mark Roles
Prodigy 50 points

I can write to an LCD via serial data just fine, but how do I send serial data out thru the USB host on the BeagleBone?

  • 0
    TI__Guru*** 145486 points

    Can you please be more specific? I cannot understand your question.

  • 0 in reply to Bin Liu
    Prodigy 50 points

    I want to communicate to a USB-to-GPIB interface and need to know just how to send a text thru the USB. to the GPIB device. Such as a query to find out what divice ID it is with a command sent out as *IDN?

  • 0 in reply to Mark Roles
    TI__Guru*** 145486 points

    Do you already have the proper driver installed/configured on BeagleBone to support your USB-to-GPIB device? Do you already have the device node /dev/ttyUSB0 or similar?

  • 0 in reply to Bin Liu
    Prodigy 50 points

    I have the drivers and show /dev/usbdev1.1 & /dev/usb2.1 on the BeagleBone Which one of these is the USB Host?

  • 0 in reply to Mark Roles
    TI__Guru*** 145486 points

    In your use case, you don't need to care about the USB host. You just need to find out where the device node of your USB-to-GPIB adapter is, something similar to /dev/ttyUSB0, and your application will talk to the node.

    Compare before and after plugged in the adapter to see if /dev/ has any new node created. Otherwise, you have to get the proper driver for your adapter.

    The following link might be helpful: Opensuse Linux and the Prologix GPIB to USB converter.

  • 0 in reply to Bin Liu
    Prodigy 50 points
    • Thanks for the timely responds. The GPIB-USB is being shipped to me now, so I will wait till I get it and make sure that I see where the device node of your USB-to-GPIB adapter is before I will ask anymore questions. Thanks for clarifying that I need to worry about the device node and not just the USB HOST.
  • 0 in reply to Mark Roles
    Prodigy 50 points

    OK, I now have the Prologix USB-GPIP Controller, and it dose indeed show up as /dev/ttyUSB0. And when I send a command like

    echo *IDN?\r\n > /dev/tty USB0

    I then see the  "TALK" LED blink. Now I guess my real problem now is just how do I capture the returning data from the USB-GPIB controller? Hopefully there is just a few lines of  C++ code  I need to make this happen.

  • 0 in reply to Mark Roles
    TI__Guru*** 145486 points

    Mark Roles said:
    OK, I now have the Prologix USB-GPIP Controller, and it dose indeed show up as /dev/ttyUSB0.

    Great, now the USB device is enumerated. The job of USB is done from application's perspective.

    Mark Roles said:
    Now I guess my real problem now is just how do I capture the returning data from the USB-GPIB controller?

    I think so. now you don't need to care about USB any more from your application's perspective, just need to figure out how to talk to GPIB device. Unfortunately I cannot help on that, I guess you need to read GPIB documents?