Hi - I'm bringing up a board http://recycle.lbl.gov/llrf4/ with a hardware and software USB stack based on and (for this purpose) equivalent to the GNU Radio design, and measured its USB data transfer capabilities more carefully than I have done before. There is a distant possibility someone on this list might make use of the result, so here it is:
Reading only, on a lightly loaded AMD64 3500+ machine (2.2 GHz, dual-channel RAM), I can sustain 35.7 MByte/sec without errors. Attempting 35.8 MByte/sec, packets get dropped left and right. The host end of the USB is a VT8237 Chipset, seemingly run in EHCI mode by Linux-2.6.16 (Debian sid 2.6.16-2-amd64-k8). I think the limitation is on the 8051 end. One 512-byte packet takes 8.53 microseconds to cross the USB channel, and the 35.7 MByte/sec sustained rate implies the 8051 sets up the next packet in only 5.81 microseconds. I don't think there is any pipelining at this level. - Larry _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
