Re: force USB_SPEED_FULL for device
Alan Stern <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
On Fri, 27 Jul 2007, Gabriel Maganis wrote: > Hello Alan, > I guess I'm trying to bypass the code that makes it so it can't > possibly work. I'm trying not to say what it is I'm trying to do in > general I guess :). But I really would just like to be able to send > that packet. Would you know if the code I might look at is in usbcore > or should I look at the HCD code? I've tried grepping around quite a > bit but I'm not sure what it is really I should look for. It isn't code at all -- it won't work because of the hardware! The low-speed keyboard's USB interface hardware is looking for signals at 1.5 MHz. If the computer starts sending full-speed data, it will be modulated at 12 MHz. Furthermore, at low-speed a 0 is indicated by a high voltage on the D- line whereas at full-speed a 0 is indicated by a high voltage on the D+ line. (Or maybe I have them reversed, but one is definitely the opposite of the other.) The keyboard's hardware can't possible cope with that. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel