Just saw this thread now... I'm seeing this problem with my USRP2s and the WBX board. However, I'm not using UHD. Do you know a fix for this outside of UHD?
On Tue, Sep 14, 2010 at 5:28 PM, Josh Blum <[email protected]> wrote: > FYI - in the future this will go away in the future when tx flow control > becomes host-based (and away from ethernet pause frames). -Josh > > > On 09/14/2010 01:56 PM, Marc Epard wrote: > >> I've been attempting to do a full duplex send/recv using UHD on a USRP2 >> with an XCVR2450. >> >> The major problem I had was that issue_stream_cmd nearly always resulted >> in a runtime error of "usrp2 no control response". It worked fine if I >> transmitted w/o receiving or received w/o transmitting. The same code also >> worked when using a 2nd USRP2 for receiving. >> >> After a session with Wireshark and the UHD host source, I had my "Well, >> duh" moment. When you call send, the data starts streaming to the USRP2 >> right away -- even if you specify a timestamp in the future. The USRP2 >> starts sending back PAUSE frames almost immediately, which throttles not >> only additional send data, but also any commands to the control port. >> >> The solution is to call issue_stream_cmd first (and start the recv >> thread), then start the send thread. This was simple enough in my app >> because I was specifying start times in the future anyway. It does prevent a >> method I was going to use on a WBX where I start the send thread once and >> scan through several receive frequencies before stoping the send thread. >> >> Perhaps most of you knew about this gotcha already, but I hope this will >> help someone else who encounters the problem. Anyway, it was fun >> investigating and I learned a lot more about the UHD host code and protocols >> >> -Marc >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
_______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
