Alan Stern wrote: > On Wed, 2 Aug 2006, Aras Vaichas wrote: >>We suspect we might be having some problems with a radiation source of around >>13MHz that might be causing problems with the 12Mbps full speed USB, we'd >>like >>to try running it at the 1.5Mbps speed to see if this fixes the problem (and >>confirms our suspicions). >> >>As a quick test I tried moving the pull-up resistor to the D- line, but that >>doesn't work and the host doesn't recognise the device at all. > > You don't even get a "low-speed device connected" message in the debugging > log? That's surprising; nothing more than a pull-up resistor should be > needed for that. Even with no device controller at all you should still > get that message.
Sorry, I forgot to mention that. Yes I do get low level system messages, but it doesn't go any further. I guess I meant "at all" and not "at all at all" :P Aug 2 14:08:36 gentoo usb 1-6: new low speed USB device using ohci_hcd and address 40 Aug 2 14:08:36 gentoo usb 1-6: device descriptor read/64, error -110 Aug 2 14:08:36 gentoo usb 1-6: device descriptor read/64, error -110 ... Aug 2 14:08:38 gentoo usb 1-6: device not accepting address 43, error -110 > No you can't. The requirements for low-speed devices are more strict than > they are for full-speed devices. For example, the maxpacket value of ep0 > has to be 8 at low speed, but it is allowed to be any power of 2 between 8 > and 64 at full speed. Also, iso and bulk transfers are allowed at full > speed but they are illegal at low speed. > > Not to mention that the electrical signals on the bus differ for the two > speeds. Hardware capable of working with 12 MHz signals might not be > capable of working with 1.5 MHz signals. > > Alan Stern Thanks, this is useful to know. regards, Aras Vaichas ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
