On Tue, Dec 25, 2012 at 12:28 AM, Alan Stern <st...@rowland.harvard.edu> wrote: > (Although I don't believe Apple uses > UHCI components in their machines.)
Supposedly Apple uses Intel chipsets now and will have UHCI along with the EHCI controller (Intel and Via usually use UHCI and others use OHCI, as per Wikipedia). Ref: http://en.wikipedia.org/wiki/Host_controller_interface_(USB,_Firewire) But indeed you are right I do not see UHCI components in my Mac Mini 2011. Root <class IORegistryEntry> 1: EHCI Root Hub Simulation@1D,7 <class IOUSBRootHubDevice> 2: HubDevice@fd100000 <class IOUSBHubDevice> 3: IR Receiver@fd110000 <class IOUSBDevice> 4: PROLiNK PCC3220@fd130000 <class IOUSBDevice> 1: EHCI Root Hub Simulation@1A,7 <class IOUSBRootHubDevice> 2: HubDevice@fa100000 <class IOUSBHubDevice> 3: BRCM20702 Hub@fa110000 <class IOUSBHubDevice> 6: Bluetooth USB Host Controller@fa113000 <class IOUSBDevice> 4: USB2.0 Hub@fa130000 <class IOUSBHubDevice> 7: Amontec JTAGkey-2@fa131000 <class IOUSBDevice> 8: usb serial converter@fa133000 <class IOUSBDevice> 9: USB Receiver@fa134000 <class IOUSBDevice> 10: FT232R USB UART@fa132000 <class IOUSBDevice> 5: USB Keyboard@fa120000 <class IOUSBDevice> >> Besides this most HID devices don't really need a 1 ms poll rate, ie the >> world >> fastest typists type 200 words per minute *peak*, which is a 1000 chars / >> minute, >> so about 16 keys / second, which is blazingly fast, but still nowhere 500 >> events >> / second. > > On the other hand, it doesn't require much agility to move a mouse > faster than 16 pixels/second. But I agree that HID devices do not > need to e polled 1000 times per second, as a general rule. In fact, > many HID devices run at low speed rather than full speed, and USB > demands that low-speed devices may not have polling intervals less than > 10 ms. That is true. But for generic USB device which use HID to avoid driver under Windows, full speed USB with 1ms bInterval will help. If there are high speed high bandwdith HID device, then the speed can go to 24MB/sec and it can replace isochronous device. But Microsoft does not support high speed high bandwidth interrupt endpoint for Windows, not so sure about Mac OS X and Linux. Reference: http://www.osronline.com/showthread.cfm?link=161236 http://www.winvistatips.com/usbehci-sys-bug-high-bandwidth-interrupt-endpoints-t182832.html http://www.cypress.com/?id=4&rID=31709 http://www.lvr.com/usbfaq.htm And actually Windows HID driver does not support alternative interface, this limit high speed HID device to top at 64Bytes/125us = 512KB/sec speed. If not for this limitation, high speed HID device (up to 24MB/sec for high speed high bandwidth, 1024 Bytesx 3 /125us; 8MB/sec without high bandwidth interrupt endpoint, 1024Byte/125us). Ref: http://www.lvr.com/forum/index.php?topic=559.0 http://www.cygnal.org/ubb/Forum9/HTML/001121.html -- Xiaofan ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ libusbx-devel mailing list libusbx-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libusbx-devel
