Hi George, no worries, I know perfectly well how it is to have too many ambitions and too little time... :-)
I can confirm that the timestamps are correct. I have been using it for some time. The compiled RBF is not in my developer branch. I haven't even moved my recent work to git... :-/ There are some older (but should be functional) versions at: http://www.schneider-group.com/gnuradio/ The only recent changes I have made were related to debugging dropped/late tx packets due to host latency (I echo the tag fields from tx to rx). I have had some inquiries regarding the ability of the tx chain to use lower clock rates ( <48M, the xfer rate to the FX2). Apparently others have had problems with that setup. I will investigate this sometime in the "near" future. I will also try to put together some tests to fully exercise the inband functionality. Please recommend any tests you would like to see. --Eric On Tue, 2010-02-16 at 14:42 -0500, George Nychis wrote: > Hi Eric, > > Sorry for the late response here, I've been wrapped up in so many > things. > > Is your latest compiled RBF in your developer branch? There are > several people I know (some that I CC'ed) that are interested in using > the inband code. > > Last I checked, the timestamp had an issue of "jumping" which I know > you tried to fix. Last time I tried your branch, I'm not sure it was > working yet. Have you confirmed that timestamps to the host are not > jumping in any manner when there is no overrun, and have you confirmed > that timestamps are being treated properly when trying to transmit? > > Thanks a bunch for updating this code. > > - George > > > On Tue, Jan 26, 2010 at 5:32 AM, Per Zetterberg > <per.zetterb...@ee.kth.se> wrote: > > Eric Schneider wrote: > Hi all, I'm looking to be doing some more rework of > the USRP1 inband > code, specifically to align with the USRP2 VRT work. > > For those not familiar, USRP1 inband allows for > timestamped rx/tx > samples (and commands), which is very useful for TDMA > type systems. It > is a separate FPGA configuration and host side > interface. > Has anyone besides me used the current inband FPGA? > > I'm not sure who on this list is interested in such a > thing, but if you > have specific needs you want addressed, speak up now! > > A few notes on my current thinking: > > 1. I do not intent to implement VRT over USB. Only to > implement a VRT > compatible interface on the host. The USB inband > protocol will simply > serve to make that possible in the most efficient way > possible. > > 2. I don't intend to keep the existing inband packet > structure. This is > one area where interested parties really need to > provide feedback as to > supported (or supportable) feature sets. > > It is my hope that the new inband Verilog modules can > be used by other > custom FPGA builds as a standard host interface. > > For example, it has just recently occurred to me that > the FPGA side > could be made more efficient by the use of trailer > metadata rather than > headers. Since the USB packets are fixed size, I > don't really see a > downside. > > There are also fields in the current inband packet > that are either > obsolete, or should be optional fields, IMO. RSSI, > for example. > > Do timestamps really need to be 32 bits? That allows > scheduling > transmission 33 seconds in advance on a 64MHz clock, > which seems > excessive to me. > > Is there a reason to send timestamps in every packet > if samples are > contiguous? > > I'm leaning towards a 16 or 32 bit trailer with > optional, per packet, > meta data. Less than 16 bit alignment of trailer/meta > would fragment > individual (16 bit) samples, and 32 bits would keep > I/Q interleaving > order constant between packets. I am open to > entertaining the idea of > tiny (8 bit?) trailers, so long as we can reliably > detect and recover > from buffer overruns and such. > > --ETS > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > Sounds great!! > > It would also be nice to have a "pps" input to synchronize the > clocks of multiple units. General purpose pins could be used. > > One feature I have always wished for is "external triggering" > where a USRP transmits/receives when a pin goes high. But that > is maybe another project. > > Good luck! > > BR/ > Per > > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
