2013/1/11 Tim Roberts <t...@probo.com>: > Wander Lairson Costa wrote: >> I am trying to do a isochronous loop transfer, I can write the data >> but I am getting an error when trying to read it. Following are the >> logs: >
Hi Tim, First of all, thanks for the explanation. > Isochronous endpoints have peculiar rules for reading. Each packet in > an isochronous transfer maps to one microframe in real time. It's not > like a bulk or interrupt transfer where it just hangs around until it's > full. If you have 8 packets in your transfer, you'll cover 8 > microframes. If the device doesn't send anything in one of those > microframes, you'll get zero bytes back for that packet. > > The endpoint packet size is 32 (in the header), and your request is for > 128 bytes, so you should be covering 4 microframes. It's quite normal > for one of those packets to fail when the other ones succeed. That what > it looks like here -- packet 0 failed, but the other three did not. > I have done a mistake here, the logs I sent are for a transfer of 32 bytes. When I try to transfer 128 bytes, all packets fail with -71 error. > Error -71 is EPROTO, suggesting a protocol violation. I guess that > implicates the firmware. I agree that it is probably a firmware problem. > Have you done an lsusb to make sure the > descriptors match what you expect? > Yes. I don't have the hardware right now but I should have posted output of lsusb for the device. -- Best Regards, Wander Lairson Costa ------------------------------------------------------------------------------ Master HTML5, CSS3, ASP.NET, MVC, AJAX, Knockout.js, Web API and much more. Get web development skills now with LearnDevNow - 350+ hours of step-by-step video tutorials by Microsoft MVPs and experts. SALE $99.99 this month only -- learn more at: http://p.sf.net/sfu/learnmore_122812 _______________________________________________ libusbx-devel mailing list libusbx-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libusbx-devel
