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

Stefano Speretta s.speretta at isispace.nl
Wed Jul 15 09:09:23 EDT 2015

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.


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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