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see
papers at http://www.usb.org/developers/whitepapers/ especially http://www.usb.org/developers/whitep...therboards.pdf http://www.usb.org/developers/whitepapers/white-4c.pdf for details on the designs On Fri, 12 Sep 2003 16:32:00 GMT, "Marc Reinig" wrote: I think we really have two issues, 1. The OP had a problem with not being able to run a bus powered USB device when his host was turned off. I presume that this was because there was no Vusb present on the bus to power his device. Adding a powered hub will not help here because, with no Vusb from the host, the hub will not enable (power) any down stream ports.e There is standby power there, but because of limits on 5vsby, only low power devices will be able to receive power from a mother board connection. This is aleviated by a powered hub. 2. Separate issue: some hosts are reported to support some USB devices, for wake-up, when they are supposedly powered off. Vendors do many non standard things in the BIOS. The last I looked, this would be one, so I have some questions on these features, if anyone want to take the time ;=): a. If you execute a Shutdown from the Start Menu (Turn Off on the XP Start Menu as opposed to StandBy), can you wake your system with your mouse or keyboard? Is the power light on, off or flashing? Depends on the systems. Most systems will not have any lights on. Some will still have the light on an Optical mouse on. A book pc I have has a single light that only comes on when the system is "turned off" with a shutdown. Does the same with Win98/2k/XP and mandrake or knoppix Linux. The keyboard powers the system up through a complete reboot. Power off in an ATX system is really a super standby where the system can be awakened by many events such as WOL, WOM, and Keyboard/mouse. b. When your system powers on, does it go through the full BIOS check, etc? Yes. Full startup c. My MS keyboard has a sleep button on it, which puts the system, almost instantly, into a sleep mode from which it can be wakened by a press of a key. But, this is not a powered down mode, the power light is flashing, not off, RAM is still powered and refreshed, etc. I assume this is not what we are talking about. Most multimedia keyboards have 2 related buttons. One is the sleep button, the other does a power off, just like the front panel push button. Does the same soft off function, and a full restart happens when the power button (or power key on keyboard so equiped or configured) is pressed. d. Do your USB keyboards and mice still power on the system when connected through an external hub when your system is in this powered down (but apparently not out) mode or do they need to be plugged into the root hub, i.e. does the BIOS support hub devices or just mice, keyboards, etc. that are directly attached? Depends on the hub. I have 2 belkins and a "scitek (sp?)" that do support power up. I have had others that don't e. Do all USB ports receive power when the system is in this state, or only ones that have a mouse, keyboard or bootable device attached? Thanks in advance, Seems to be power to low power devices from the mother board. Many powered hubs will have power to any device plugged in. For example, on my cheap Belkin hub, I have a wireless network adapter and optical mouse that are powerered on (at least the power lights are on) as long as the hub is powered, no matter if the computer is on, or plugged in, or the hub is plugged into the computer. My USB2.0 hub powers off the Wireless adapter (which at 500ma is a high power device) while my mouse stays on. Other non pointing devices have stayed on as well (for example a powerline network interface). The point seems to be that pointing/human interface devices (mice and keyboards) mostly still receive power. High powered devices don't unless on a powered hub that constantly supplies power, and other devices - it depends on the powered hub/motherboard. I have seen in the options for some USB 10/100 network interfaces the option to "wake on lan", so I assume they are expecting power even in soft off. The specs are not specific on requirements there. Marc Reinig System Solutions This is "Jim Turner" wrote in message ws.com... Can't give specifics right now. I know that various multimedia keyboards that are USB and have the power button on them from Microsoft, Logitech, and some others will wake up motherboards I have tried it on from ASUS, ECS, and MSI, although don't have specifics handy right now. Just have to have legacy USB support on in the BIOS, and a real ATX system. Modern ATX systems don't completely power off unless you pull the plug or throw the switch on the back of some power supplies. The 5vsb voltage is there to the PS/2 ports and some USB ports. Have seen some of the optical mice with the lights on and the system "off". JT PS. haven't done anything with Macs for years. On Tue, 09 Sep 2003 23:34:24 GMT, "Marc Reinig" wrote: Can you tell me which USB keyboards or USB network adapters can wake a Windows PC when the PC is turned off or which Windows PC keeps USB power on when they are shut off? We're not talking about standby, we're talking about OFF. Perhaps you are thinking of the ability to turn on a MAC through the keyboard? I don't think the above things are possible in Windows. Marc Reinig System Solutions |
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