[USRP-users] USRP B210 Sometimes Not Appearing with lsusb

devin kelly dwwkelly at gmail.com
Wed Jul 15 11:54:06 EDT 2015

Thanks for the help.  The boards I'm using are Atom based (which is x86_64,
not ARM) just to be clear.  I'm on Ubuntu 14.04 so maybe using a newer
kernel would help?

Also, I've noticed that my USRPs will sometimes fall back to USB 2.0
despite being plugged into a USB 3.0 port.  Could this be related?  Is
there anything I can do to encourage the USRP to always come up in USB 3.0


On Wed, Jul 15, 2015 at 9:09 AM, Stefano Speretta via USRP-users <
usrp-users at lists.ettus.com> wrote:

> I had the exact same problems with the setup you described (with and
> without a USB3 hub that had an external power supply). After a lot of tests
> it seemed a limitation on the Linux side because everything worked fine on
> a Windows7 machine. BTW, all the tests were performed on a Dell R210 with
> Debian stable and Windows 7.
> Cheers,
> Stefano
> On 7/15/2015 04:55, Marcus D. Leech via USRP-users wrote:
>> On 07/14/2015 10:21 PM, devin kelly via USRP-users wrote:
>>> Hello,
>>> I have several Intel NUC single board computers (the Atom based ones).
>>> Sometimes I'll reboot them with my USRP B210 plugged in or just unplug and
>>> plug in the USRP and the USRP will still behave as if it's unplugged.
>>> There won't be any log messages in dmesg and lsusb won't find the USRP.
>>> I have the right udev rules installed and un-plugging and replugging the
>>> USRP (including the power supply) back in always seems to work.  Once lsusb
>>> can find the USRP everything works fine.
>>> It seems like if we plug in the USB first and then the external power
>>> supply the USRP comes up fine, when we swap the order it's not as reliable.
>>> We have an external power supply that is at 5.6 V but gets loaded down
>>> to 5.3 V with the USRP plugged in.  After looking at the schematic it seems
>>> like 5V should be fine.
>>> Has anyone had any issue like this?  How should we start debugging?
>>> Thanks,
>>> Devin
>>>  I have seen this on ARM embedded boards as well, like on the XU3 and
>> U3.  I made it vastly more reliable by having a cheap USB-3.0 hub between
>> the host USB port and the USRP.  My suspicion is that this is USB PHY-layer
>> weirdness.
>> From the PHY-layer perspective, the FX3 on the B2xx is setup exactly as
>> Cypress recommends.   The USB-3.0 controller ecosystem appears to be still
>>   somewhat immature, and it's still somewhat unpredictable whether any
>> given controller will work for any randomly-selected USB-3.0 device.
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