[USRP-users] Still problems with the b210...

Ralph A. Schmid, dk5ras ralph at schmid.xxx
Wed Oct 29 03:01:23 EDT 2014


despite all the new uhd releases, I still have the issue with the bigger
sampling rates. Other projects became a bit more calm now, so I want to
throw some of my time onto the problem. 

To recall the story, my b210 (ur uhd) freezes USB on my virtual machine when
sampling rates exceed 8 MS/s. At 32 MS/s it is a matter of seconds to very
few minutes until the system hangs. This seems to be not the issue with
disconnecting USB any more, this problem is gone, but I have no idea if they
somehow are related.

My test scenario is uhd_fft or gqrx. Everything is always on latest release,
built from source, no precompiled binaries. The OS is Kubuntu 14.04, I can
reproduce the same behavior with Kubuntu 12.04 or 14.10, no matter if using
existing VMs or freshly installed systems. 

When the freeze happens, USB connectivity seems totally gone, commands like
lsusb just hang and do not come back, and even a system shutdown does not
complete, I have to switch of the VM the hard way. 

Now one could think this is a machine issue - but for sure it has to do with
uhd somehow, as Nuands BladeRF runs with 30 MS/s for hours, using the same
Cypress FX3 USB controller. The tool chain for the BladeRF is similar, gqrx,
gnuradio, gr-osmosdr, the only difference is uhd. All within the same VM. 

On the same machine within the Windows host system the b210 runs for hours
at 32 MS/s. So the hardware looks OK, also do USB controllers and USB
cables. Adding an USB3 hub with external power changes nothing, neither does
using the supplied 6V power supply for the b210. 

This complete USB stall looks to me like some issue on a deeper layer, in
the interaction with the OS.

Now is my knowledge of all this Linux stuff very limited, and to collect
more debug information I need one who can take me by the hand and point me
to the right direction, where to look, what to collect. I am not very
familiar with log file parsing and reading, especially the powerful looking
commandline tols for this are new to me. 

Thank you very much for any input - I really would love full functionality
of my 1k$ toy :)

With best regards



Ralph A. Schmid
Mondstr. 10
90762 Fürth
ralph at schmid.xxx

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