> > > Hi Alan, > > > > To tell the truth I have to convince my supervisor that connecting two > > computers via their USB ports for file transfer cannot work without a > > USB bridge cable! I have already told him that the USB system must > > involve a Host and a device since this technologie was designed for that > > purpose. The USB bridge cable consists in two back to back devices using > > a simple connection to transfer data from one host to the other. My > > supervisor actually suggested that I take a look at Linux open source > > code for USB system files and try to make the usb passive > > There is no way to make a host controller passive other than turning it > off.
Do u have convincing reasons for that? > > > and try to > > simulate the signal sent on the Vbus, > > Vbus doesn't carry a signal, it only carries power. > > > to signal a usb plug on the host, > > over the D+ and D- wires! > > I don't understand that bit. Note that you can't even plug a standard > USB cable into two computers, because the cable has different sorts of > connectors at the two ends. Maybe this will be a good enough reason to > convince your supervisor that a special cable is needed! Actually my supervisor provided me with an A to A USB cable that doesn't respect USB norms. First of all, he suggested that I should try to cut the Vbus wire to overcome the power problem. But I found out that the Vbus is not only used to supply power but also involved in the process where the host detects that some hardware has been attached ( even though I couldn't really understand how it does so. It has something to do with resistors... It'd be great if someone could clarify me on this point too :) ). So once I told him about that he still suggested to cut the Vbus and simulate whatever is used to signal the device attachement on the D+ and D- wires. > > I mean on one way he might be right when he > > says that operating systems such as WIndows 98 do not recognize when > > something is attached on the USB port > > Linux won't recognize when something is attached to the USB port either, > if you unload the USB host controller drivers. (Win 98 doesn't include > USB drivers.) > > > while it is with Win XP; so it > > definitely is something in software! > > What is in software? Do you mean that USB won't run without software > support? Yes, that's correct. However it doesn't mean that changing the > software can magically change the hardware. What I meant is that WIndows 95 or 98 doesn't recognize when a USB is plugged (hot plug) in while XP does even though we are using the same hardware. The point here is that the detection of the USB plug is controlled by the software which is here the Operating System. > > > Anyway can you help me in providing > > him a sufficient answer regarding the impossibility of what he proposes > > since I can hardly find enough sources! > > Tell him the the USB hardware on a PC is designed to connect only with > devices, not with other PCs. And that a standard cable cannot be > connected to two PCs. Unfortunately I already told him that and even the issue of the power supply. I also told him that the functions done by the USB host can't be done by two entities in a USB system and that the host controller is designed to work as a host. There he asked me what makes it acts as a host what makes it impossible to convert that USB host controller into a dummy USB that will no longer do all the functions of the USB host but simply respond as a device. And here is where he suggested to have a look at Linux source code for USB and see if I can make changes in order to get that result... I really need help! thanks Alan any comment is welcome!! omar -- _______________________________________________ Find what you are looking for with the Lycos Yellow Pages http://r.lycos.com/r/yp_emailfooter/http://yellowpages.lycos.com/default.asp?SRC=lycos10 ------------------------------------------------------- This SF.Net email is sponsored by: InterSystems CACHE FREE OODBMS DOWNLOAD - A multidimensional database that combines robust object and relational technologies, making it a perfect match for Java, C++,COM, XML, ODBC and JDBC. www.intersystems.com/match8 _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
