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USB Isolator speed for XDS100v2 debugger

ab cd
Prodigy 150 points
Other Parts Discussed in Thread: TMDSDOCK28335

Hi!

I am using the experimenter kit for the 28335 right now which comes with a non-isolated XDS100v2 debugger. The functionality of this debugger is sufficient for me, except that I think I require an isolated connection to the computer due to a harsh EMI environment (power application). I am aware of various options (XDS5xx, schematics for isolated XDS100v2, F37xD controlCard,..) and evaluating them right now.

One simple possible option could be to just use an usb isolator (e.g. this one: http://www.bb-elec.com/Products/USB-Connectivity/USB-Isolators/Compact-USB-Port-Guardian.aspx). However all available isolator set the USB speed to 12MBit/s.

I have seen that XDS100v2 went up to a 480MBit/s interface speed compared to v1. So two questions arise for me:

  • would the XDS100v2 be able to communicate with my computer using such an isolator that sets the speed to 12mbit/s?
  • Will the debugging speed actually go down (significantly)? How much more than 12MBit/s does the XDS100v2 use? Or is it more a question of delay?

Right now I normally have around 30-35 expressions in my watch window at a gobal refresh rate of 100ms. I see that the system cannot hold this refresh rate (it approximately refreshed every ~500ms). 1-2 seconds would still be okay.

Thanks!

  • 0
    Guru 192875 points

    Hi,

    would the XDS100v2 be able to communicate with my computer using such an isolator that sets the speed to 12mbit/s?

    There shouldn't be any problem in using such an isolator.

    Will the debugging speed actually go down (significantly)? How much more than 12MBit/s does the XDS100v2 use? Or is it more a question of delay?

    Quite possible, its speed might get hampered.

    But also, what I feel is 12Mbps itself is a huge bandwidth and according to 30-35 expressions you're using the speed should not be hampered much.

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    TI__Guru 57255 points

    Hello ab cd,

    It might also be worth noting that if you are using the baseboard of the TMDSDOCK28335 (image: http://www.ti.com/graphics/tool/f28335_usb_dock.jpg) then the on-board emulator is actually a xds100v1.  Note that the drivers are similar between the v1 and v2.

    I believe that you should be able to add your isolator and get everything to work but I haven't tried this specifically so I cannot be certain:
    1) you may need to edit the interface's speed settings in your CCS target configuration.  I would recommend  trying to connect to the device.  If it fails decrease the JTAG's TCK speed and then retry until things start working.  From my recollection, the target configuration speed settings are generally in a different tab (labelled something like 'advanced')
    2) with the slower speed interface you may need to decrease CCS's watch window & graph update rates.


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    Prodigy 150 points

    Thanks Brett and Gautam :-)

    It is good to know that the on-board debugger is an XDSv1, I always thought it would be v2. I will report here about my experience, if I end up using this solution.

  • 0 in reply to ab cd
    Guru 192875 points

    Sure, do share your experience!

    Goodluck & Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Prodigy 150 points

    Results:

    The debugging process works with this USB Isolator without any further restrictions, could not see any limitations on speed or anything else.
    The problem might have been somewhere else, too. But it is part of a working configuration now. More details:

    http://e2e.ti.com/support/microcontrollers/c2000/f/171/p/341804/1194848.aspx#1194848

    Thanks,
    Marten

  • 0 in reply to ab cd
    Guru 192875 points

    The debugging process works with this USB Isolator without any further restrictions, could not see any limitations on speed or anything else.

    That's great, Marten!

    Goodluck & Regards,

    Gautam