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

Marcus D. Leech mleech at ripnet.com
Tue Jul 14 22:55:53 EDT 2015

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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