Why does wireless USB transmitter reboot XP?

[aeroloose]

Running XP Home SP3 on a Gateway tower. I use an older MS
wireless mouse with a USB transmitter. Occasionally, I
remove the transmitter & plug it into the mouse base to turn
off the mouse - this older unit doesn't have the smart
battery-save feature. Sometimes, when I re-insert the
transmitter into the USB port, the computer reboots! It can
happen at the logon screen, or at the desktop. It's random
- can go for days without issue, then will reboot twice in a
day. It doesn't seem to hurt anything (yet) but I'm still
curious.

Any thoughts?

Aero

 

[Paul]

Running XP Home SP3 on a Gateway tower. I use an older MS wireless
mouse with a USB transmitter. Occasionally, I remove the transmitter &
plug it into the mouse base to turn off the mouse - this older unit
doesn't have the smart battery-save feature. Sometimes, when I
re-insert the transmitter into the USB port, the computer reboots! It
can happen at the logon screen, or at the desktop. It's random - can go
for days without issue, then will reboot twice in a day. It doesn't
seem to hurt anything (yet) but I'm still curious.

Any thoughts?

Aero

I was trying to find a nice diagram of what happens, but can't find it now.
Intel has a nice oscilloscope picture, showing what happens when a USB
device is plugged into its socket.

The USB ports on the motherboard, are supposed to have a bypass capacitor.
The circuit would look roughly like this.

+5VSB ----- Polyfuse -----+------ VBUS
|
--- 100uf <--- USB peripheral
--- bypass <--- plugs in here
|
Ground -------------------+------ Ground

The USB peripheral (in your case, a tiny transmitter), may have
its own bypass capacitor. When you insert the plug "hot" with
the system running, the bypass capacitor on the USB peripheral
tries to charge up instantly. This causes a large transient
current to flow, for a short time.

The Intel document, shows that current can be as high as 5 amps or so,
but for a very short instant. The interval is short enough, the
Polyfuse doesn't have time to react.

It causes the +5VSB rail voltage (the left hand side of the diagram)
to dip like this.

+5VSB -------- ---------
\ /
\/

Now, another circuit powered by +5VSB, is the chip that drives PS_ON# to
the ATX power supply. If that chip loses power for a moment, it
stops driving PS_ON# to ground (ON state). So your PS_ON$ might look
like this. During the "bump", the power supply is told to turn off
all its main outputs.

/\
/ \
PS_ON# ------ ---------

If a USB peripheral manufacturer knows they're going to cause
this issue, there are "inrush limiter" chips, which can control
the transient. If the bypass cap inside the USB peripheral was
over 10uF, they might use such a circuit. Since the chips cost
money though, it's easier to leave them off.

If the motherboard had an inadequately sized bypass capacitor,
like smaller than 100uF shown in the original diagram above, that
might contribute to the problem. And a capacitor failure, where
the value of capacitance is significantly less than the value
printed on the plastic sleeve, could result in a similar behavior.

There are other possible explanations, such as coupling between
the +5V line and some other sensitive circuit (inductive coupling
of the transient, into say, a reset signal). But just as easily,
it could be the power pin on the USB connector, is dragging down
that power supply rail long enough, to cause Power_Good to go
false and cause a reboot.

As Elmo suggested, a USB hub with its own wall adapter power supply,
should stop the transient. It would provide isolation between the
two parties. Of course, the down side of using hubs, is sometimes
the USB function of the device is affected, by placing a hub between
it and the computer. So using a hub isn't always a "win-win".

http://www.newegg.com/Product/Product.aspx?Item=N82E16817111981

Even the usage of a USB extension cord, between the USB transmitter and
the port on the computer, *might* be enough to "tame" the transient
to reduce the frequency of occurrence. A length of wire can
change the dynamics. (And I didn't even think they made these.)

http://www.newegg.com/Product/Product.aspx?Item=N82E16812270104

Using the hub, is an attempt at a solution, when the motherboard
is less than successful at preventing the transient.

Paul

 

[aeroloose]

I was trying to find a nice diagram of what happens, but
can't find it now.
Intel has a nice oscilloscope picture, showing what happens
when a USB
device is plugged into its socket.

The USB ports on the motherboard, are supposed to have a
bypass capacitor.
The circuit would look roughly like this.

+5VSB ----- Polyfuse -----+------ VBUS
|
--- 100uf <--- USB peripheral
--- bypass <--- plugs in here
|
Ground -------------------+------ Ground

The USB peripheral (in your case, a tiny transmitter), may have
its own bypass capacitor. When you insert the plug "hot" with
the system running, the bypass capacitor on the USB peripheral
tries to charge up instantly. This causes a large transient
current to flow, for a short time.

The Intel document, shows that current can be as high as 5
amps or so,
but for a very short instant. The interval is short enough, the
Polyfuse doesn't have time to react.

It causes the +5VSB rail voltage (the left hand side of the
diagram)
to dip like this.

+5VSB -------- ---------
\ /
\/

Now, another circuit powered by +5VSB, is the chip that
drives PS_ON# to
the ATX power supply. If that chip loses power for a moment, it
stops driving PS_ON# to ground (ON state). So your PS_ON$
might look
like this. During the "bump", the power supply is told to
turn off
all its main outputs.

/\
/ \
PS_ON# ------ ---------

If a USB peripheral manufacturer knows they're going to cause
this issue, there are "inrush limiter" chips, which can control
the transient. If the bypass cap inside the USB peripheral was
over 10uF, they might use such a circuit. Since the chips cost
money though, it's easier to leave them off.

If the motherboard had an inadequately sized bypass capacitor,
like smaller than 100uF shown in the original diagram above,
that
might contribute to the problem. And a capacitor failure, where
the value of capacitance is significantly less than the value
printed on the plastic sleeve, could result in a similar
behavior.

There are other possible explanations, such as coupling between
the +5V line and some other sensitive circuit (inductive
coupling
of the transient, into say, a reset signal). But just as
easily,
it could be the power pin on the USB connector, is dragging
down
that power supply rail long enough, to cause Power_Good to go
false and cause a reboot.

As Elmo suggested, a USB hub with its own wall adapter power
supply,
should stop the transient. It would provide isolation
between the
two parties. Of course, the down side of using hubs, is
sometimes
the USB function of the device is affected, by placing a hub
between
it and the computer. So using a hub isn't always a "win-win".

http://www.newegg.com/Product/Product.aspx?Item=N82E16817111981

Even the usage of a USB extension cord, between the USB
transmitter and
the port on the computer, *might* be enough to "tame" the
transient
to reduce the frequency of occurrence. A length of wire can
change the dynamics. (And I didn't even think they made these.)

http://www.newegg.com/Product/Product.aspx?Item=N82E16812270104

Using the hub, is an attempt at a solution, when the
motherboard
is less than successful at preventing the transient.

Paul

Thanks, an excellent explanation. The voltage drop theory
seems reasonable. I do have one of those USB extensions;
I'll try it first and see what happens.

 

[aeroloose]

Two things I would try:

1. Open Device Manager, open the properties on each "USB Root Hub",
click the Power tab, and deselect "Allow the computer to turn off this
device to save power". This could help if the computer enters Sleep or
other mode, that turns off the USB hubs. I've never heard of that being
a problem, but thought it might be with a try.

2. Get a powered USB hub, i.e. one with its own power adapter. This
could help if too much power is being drawn by USB devices. A sudden
voltage drop could be just enough to cause a component to shut down.

Elmo,

Thanks for the ideas to try. #2 is similar to Paul's
theory, so I'll try the USB extension first. It's my
no-cost option

 

[aeroloose]

Elmo,

Thanks for the ideas to try. #2 is similar to Paul's theory,
so I'll try the USB extension first. It's my no-cost option

Sorry, forgot to include this in my earlier reply. None of
my USB Root Hub "Power" tabs have a checkbox for a
power-save option. Each hub said it was self-powered, and
noted 500mA per port.

Aero

 

[Tecknomage]

Thanks, an excellent explanation. The voltage drop theory
seems reasonable. I do have one of those USB extensions;
I'll try it first and see what happens.

A very basic suggestion/question, and I am assuming by "transmitter"
you are talking about the device that connects directly to your tower.

WHY are you doing this operation with your system ON?!!!

Your mouse (wireless or not) is a basic control interface, you should
not be disconnecting mice with your system on.

Turn your system off to recharge your mouse's wireless transmitter.
Better, get a new warless mouse with a transmitter that can
charge/power from your USB port (hopefully your tower has *USB2*
support).

Of course this does NOT apply to your mouse itself. Hopefully it uses
a good lithium "coin" battery or you use AAA lithium batteries.

 

[ArameFarpado]

Em Domingo 14 Novembro 2010 01:38, aeroloose escreveu:

Running XP Home SP3 on a Gateway tower. I use an older MS
wireless mouse with a USB transmitter. Occasionally, I
remove the transmitter & plug it into the mouse base to turn
off the mouse - this older unit doesn't have the smart
battery-save feature. Sometimes, when I re-insert the
transmitter into the USB port, the computer reboots! It can
happen at the logon screen, or at the desktop. It's random
- can go for days without issue, then will reboot twice in a
day. It doesn't seem to hurt anything (yet) but I'm still
curious.

Any thoughts?

Aero

Electrical short circuit at the moment you plug the connector out of
alignment.
Usual problem with usb connectors especialy when they are loose from use.

 

[aeroloose]

A very basic suggestion/question, and I am assuming by "transmitter"
you are talking about the device that connects directly to your tower.

WHY are you doing this operation with your system ON?!!!

Your mouse (wireless or not) is a basic control interface, you should
not be disconnecting mice with your system on.

Turn your system off to recharge your mouse's wireless transmitter.
Better, get a new warless mouse with a transmitter that can
charge/power from your USB port (hopefully your tower has *USB2*
support).

Of course this does NOT apply to your mouse itself. Hopefully it uses
a good lithium "coin" battery or you use AAA lithium batteries.

I unplug the transmitter during use (when I leave the PC for
periods of time) because it fits in the bottom of the mouse
and turns the mouse off. I get months of mouse battery life
this way, vs. days / weeks if I leave it permanently plugged in.

 

[aeroloose]

Em Domingo 14 Novembro 2010 01:38, aeroloose escreveu:



Electrical short circuit at the moment you plug the connector out of
alignment.
Usual problem with usb connectors especialy when they are loose from use.

Thanks, that's a thought. I always use the lower port, to
keep the upper port free for other devices. I'll try the
upper port for a while and see if the phenomenon stops.