Is my USB wireless keyboard not hot-swappable?
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From: AdeW on 5 Dec 2009 21:45 On 5 Dec, 08:20, Paul <nos...(a)needed.com> wrote: > > USB, I don't have concerns about that, with at > least the hot swap end of things. The only motherboard > I'm careful with, is my P4C800-E Deluxe, due to it > having the failure-prone ICH5R. If I use the USB on > that system, I plug the USB device in with the power > off. There have been enough failures of ICH5/ICH5R > without me adding to the list. I don't have to worry > about that with the other machines. My current VIA > based system has been trouble free on USB. > > Paul If its dependant on the motherboard, I have a Dell computer which has the USB sockets at the back Mar 2000 (ship date) Optiplex GX1 Pentium III (I've looked inside and can't see a model # on the motherboard) and... ....two others I get to use which have the USB sockets at the front... Dell Optiplex 740 AMD Athlon 64, WinXP 2002 SP3 and Dell Dimension 3100 Pentium 4 WinXP 2002 SP3. Would their motherboards be likely to be modern enough? Does having the USB socket at the back of the Mar2000 Pentium III one give a clue as to how robust it is?
From: Paul on 5 Dec 2009 21:58 AdeW wrote: > On 5 Dec, 08:20, Paul <nos...(a)needed.com> wrote: >> USB, I don't have concerns about that, with at >> least the hot swap end of things. The only motherboard >> I'm careful with, is my P4C800-E Deluxe, due to it >> having the failure-prone ICH5R. If I use the USB on >> that system, I plug the USB device in with the power >> off. There have been enough failures of ICH5/ICH5R >> without me adding to the list. I don't have to worry >> about that with the other machines. My current VIA >> based system has been trouble free on USB. >> >> Paul > > If its dependant on the motherboard, I have a Dell computer which has > the USB sockets at the back Mar 2000 (ship date) Optiplex GX1 Pentium > III (I've looked inside and can't see a model # on the motherboard) > and... > > ...two others I get to use which have the USB sockets at the front... > > Dell Optiplex 740 AMD Athlon 64, WinXP 2002 SP3 and > Dell Dimension 3100 Pentium 4 WinXP 2002 SP3. > > Would their motherboards be likely to be modern enough? > > Does having the USB socket at the back of the Mar2000 Pentium III one > give a clue as to how robust it is? The point of my statement was, that instances of designs that have problems with USB port reliability are relatively rare. Intel has not admitted there is a problem with ICH5/ICH5R. The only site admitting there is a problem with chips like that, is the Gigabyte site. They are mainly concerned with static discharge. I'm not convinced their analysis is totally correct. There was one user who had a USB failure that happened when his system was rebooted. In that case, the initial damage may have been by static, but the only trigger was the reboot. I think there is more to the issue than just static electricity. But if Intel chooses to not explain the problem, we'll never know. I'm sure Intel has done post-mortem analysis and knows exactly what the mistake was. http://tw2005.giga-byte.com/Motherboard/Support/FAQ/FAQ_456.htm Your Dimension 3100 comes just after that generation of chip, so should not have a USB issue. The 915GV likely has something like ICH6 on it. Using a utility like Everest, you may be able to list the hardware inventory in the computer, and figure it out from that. http://support.dell.com/support/edocs/systems/dim3100/en/sm/specs0.htm#wp1052310 Other brands and model numbers of chips should not have a problem. The only other instance I know of, is PCI USB2 cards with NEC chips, tend to be static sensitive. I've seen reports from a number of people, where one or more ports on their PCI USB2 cards end up blown. While the other ports continue to work. The ports seem to fail independently on the NEC chip. The above Gigabyte article makes a reference to ICH4 also having the problem, but I haven't seen evidence of that in the newsgroups. Whenever the USB problem shows up, it seems to be the ICH5/ICH5R at fault. If it is happening to ICH4, nobody has complained about it. Paul
From: kony on 6 Dec 2009 00:00 On Sat, 5 Dec 2009 18:41:41 -0800 (PST), AdeW <adnw14(a)live.co.uk> wrote: >> Generally a wireless keyboard has a microcontroller in it's >> base receiver that makes the system think there is a >> keyboard even if the physical keyboard isn't present at all, >> so yes it should be fully hot swappable within the >> limitations we've already mentioned, that if the bios needs >> to detect it prior to drivers loading, it would need plugged >> in when the system enumerates the hardware after POST.- Hide quoted text - >> >> - Show quoted text - > >So in other words what you're saying is the PC would have to be >restarted if the keyboard was plugged while Windows was running. No, the PC would have to be restarted to use the keyboard outside of an operating system that loads a keyboard driver if the keyboard had not been plugged in already when the BIOS initializes. For example, put in a memtest86+ boot floppy (or bootable USB drive, etc) and turn on or reset the system and let it boot to it without the keyboard yet connected, and you may not be able to use the keyboard, BUT if you had the keyboard already plugged in when the system was turned on or reset, and the bios settings are right, you could use the keyboard in such mini-OS environments that don't load their own keyboard driver.
From: DevilsPGD on 6 Dec 2009 00:44 In message <hfcljh$235$2(a)news.eternal-september.org> Barry Watzman <WatzmanNOSPAM(a)neo.rr.com> was claimed to have wrote: >No, wrong, not ALL USB devices are hot swappable. But USB keyboards >are. However, if a USB keyboard is not plugged in when the system is >powered up, some BIOS' will not subsequently recognize one if it is >plugged in later. It depends on the bios, and, also, on some of the >settings inside the bios to enable/disable USB keyboards (this is bios >and therefore motherboard dependent). Doesn't the USB interface require hotswapping at an electrical level? Sure, you'll find cases where the device or driver needs notice to avoid data loss, or but you're electrically safe to disconnect if needed.
From: Paul on 6 Dec 2009 01:53
DevilsPGD wrote: > In message <hfcljh$235$2(a)news.eternal-september.org> Barry Watzman > <WatzmanNOSPAM(a)neo.rr.com> was claimed to have wrote: > >> No, wrong, not ALL USB devices are hot swappable. But USB keyboards >> are. However, if a USB keyboard is not plugged in when the system is >> powered up, some BIOS' will not subsequently recognize one if it is >> plugged in later. It depends on the bios, and, also, on some of the >> settings inside the bios to enable/disable USB keyboards (this is bios >> and therefore motherboard dependent). > > Doesn't the USB interface require hotswapping at an electrical level? > > Sure, you'll find cases where the device or driver needs notice to avoid > data loss, or but you're electrically safe to disconnect if needed. Page 113 of USB20 spec "The connectors are designed to be hot plugged." If you pick up a USB flash drive, or even a USB cable, you can see the outside (+5V and GND) contacts are longer than the two center data contacts. That is a sign the connector was designed for hot swap. The ingredients of hot swap are 1) Ensure power and ground are established, such that I/O signals are not damaged by phantom voltages coming from the supply. (Particularly important if the hardware is powered by -48V and the I/O is a much lower voltage.) Making the contacts longer on some of the pins is how you do that. This is just to illustrate what that might look like. SATA has some pins longer than others, to sequence what makes contact first, and ensure the sensitive pins aren't exposed to out of bounds voltages. USB has this too, if you look at a USB flash stick or USB cable contacts. http://connector.almita.com.tw/rimages/304/SAAT-connector-02-B.jpg 2) Use "Failsafe" I/O pads, such that if one part of the hardware loses power, the I/O pads don't provide a sneak path. The sneak path can be things like diode protection on I/O pads. The idea is the pads don't inadvertently draw current when they're not supposed to. 3) Use a hot swap controller for power, to reduce the transient when hardware is plugged in. USB doesn't use this, and uses some design rules instead. The host connector, has 100uF across +5V and ground, to reduce the amplitude of bus voltage disturbance when a device is plugged in. The guest device should have only a small bypass cap used, since that cap needs to be charged instantly. This kind of issue is detailed in an Intel document. Failure to guard against the bus transient, can cause the second USB on a stack to misbehave or have a data glitch. USB devices are limited to 100mA before negotiation begins, but that pales in comparison to a 5 amp transient caused by charging a small capacitor inside the peripheral. On hardware with major power consumption, and hot swap capability, they gradually bring up the power on the module. That is shown in the following document. But USB doesn't do this, for reasons of economy. (Hot swap design in a non-computer application. Mentions some issues.) http://www.analog.com/library/analogDialogue/archives/42-05/hot_swap.html The kind of I/O you're connecting to, makes a difference as well. For hub architectures... Host / | \ / | \ X Y Z the I/O may be independent of one another. USB works like that. When something plugs into X, it doesn't disturb Y or Z. PCI Express is like this too. For bus based systems, it is much worse. Host ---+---+---+ | | | X Y Z Plugging into "X" with the power on here, could glitch an ongoing transaction on Y or Z to the host. Pre-charging the data pins to half-rail before contact, is one solution. In general, this is a much harder case to solve. Many sleepless nights if you do something like this. PCI has a bus architecture like this, as does the VMEBUS. PCI Express, on the other hand, is a hub, and so doing a hot swap there, wouldn't upset a neighbor. Designing for hot plug can either be extremely hard (bus based system) or relatively easy. Getting the connectors right is part of the battle. As far as I know, PS/2 has all equal length pins, so there isn't any visible design intent there for hot swap. Having the OS recognize a hardware change, is a separate but important issue. As an example, there are early SATA interfaces that are quite capable of indicating a new drive is connected, but because the driver didn't include any code (or maybe a framework wasn't available to hook to), the hardware can't tell anybody anything. For an event like that, either you can use an interrupt, to indicate something has happened on a particular interface. Or, the OS can poll the hardware at regular intervals, to check for the presence of new hardware. An interrupt scheme is preferable if available and if it is reliable. Paul |