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USB 2.0 hubs?



 
 
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  #1  
Old July 28th 18, 07:20 PM posted to microsoft.public.windowsxp.general
Bill in Co
external usenet poster
 
Posts: 1,927
Default USB 2.0 hubs?

I bought two 4-port USB ports to extend one I have on the computer, and they
both work fine, but a bit differently. When I connected each one to the
computer, it naturally found the new hardware and installed a driver, as
expected. (I'm using Windows XP)

However, for one of these items, each time you plug a different USB device
into it, it needs to initially enumerate the device, but not so for the
other. The only difference I can tell on the specs is that one is called a
USB port hub splitter, and the other lacks that term "splitter" (and that
the first one appears to be a bit more advanced (for example, allows for
external power). Here are the two items. Can someone explain why the
difference in enumeration, and that one needs to do it, while the other
doesn't?


https://www.amazon.com/UGREEN-Splitt...ds=usb+2+ports


https://www.amazon.com/AmazonBasics-...=usb+2.0+ports



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  #2  
Old July 28th 18, 08:39 PM posted to microsoft.public.windowsxp.general
Paul[_32_]
external usenet poster
 
Posts: 11,873
Default USB 2.0 hubs?

Bill in Co wrote:
I bought two 4-port USB ports to extend one I have on the computer, and they
both work fine, but a bit differently. When I connected each one to the
computer, it naturally found the new hardware and installed a driver, as
expected. (I'm using Windows XP)

However, for one of these items, each time you plug a different USB device
into it, it needs to initially enumerate the device, but not so for the
other. The only difference I can tell on the specs is that one is called a
USB port hub splitter, and the other lacks that term "splitter" (and that
the first one appears to be a bit more advanced (for example, allows for
external power). Here are the two items. Can someone explain why the
difference in enumeration, and that one needs to do it, while the other
doesn't?


https://www.amazon.com/UGREEN-Splitt...ds=usb+2+ports


https://www.amazon.com/AmazonBasics-...=usb+2.0+ports


Items at that price point, aren't likely
to have screws for easy disassembly. More likely
to be glued together.

You can try to use USBTreeView to gather VID/PID, or
you can use Device Manager Properties and HardwareID
to do much the same thing.

https://www.uwe-sieber.de/usbtreeview_e.html

If the device had some sort of aggressive power
saving, maybe it sleeps and only a plug-in event
starts the enumeration process and bus resets.
You can check the Device Manager properties
and see if there is a tick box to stop it
from "sleeping".

*******

When you see a device with external power...

1) The power input connector may not be rated to carry enough
power to run all ports at full power. A barrel connector
might handle 3 to 5 amps on a good day (specs are available).
Other connectors might be 1 amp or so (before there is a
possibility of the pins burning). The barrel connector is the
right solution for this job.

2) A great many powered hubs from China, cut corners.

a) There is an app note from a famous chip company
that makes USB 4 port hub chips, that shows
how to do powering properly. When current
starts to flow into the external connector,
it operates a small relay. The small relay
disconnects VBUS from the PC, from the hub and
the hub outputs run off adapter power. No
"reverse flow", upsetting the ATX supply,
is possible with the relay design.

You may hear a "click" if using one of those.
But at $7 retail, nobody can afford a relay. The
relay costs more than all other parts and the PCB,
combined. Forget doing it right! A $35 hub can
probably afford to use a relay inside.

b) A silly design, could use diodes. This violates
the voltage drop spec for the bus. But might still
work anyway. The best Schottky diodes I could buy
for a home project, have a reasonably small drop
at low current. But once you pump an amp through
them, they're little better than regular diodes.
And of course, in a hub design, everyone treats
the power output capability, like the thing is
"Niagara Falls". Lots of reviewers are upset because
it's not charging their iPad.

c) Some designs will just short the hub power input
to VBUS, allowing the wall adapter to push current
into the ATX PSU. It might not catch fire, but
it might not be completely stable either. I don't
have a symptom list assembled for this possibility.

The notion of external power is nice, but the
engineers "went on vacation" when designing the
feature.

If you use semiconductors to do the power switching
and protect the PC, then there are all sorts of corner
cases to worry about (where the switch device starts
to half-conduct). I had at least one external
enclosure, with some pretty weird corner case
behavior from a power perspective (the LED would
light dimly when the device was "off").

At $7, that's only enough money for one USB chip,
and once you acquire enough info to get the part
number, you can then Google for "quirks" with
the part number in question. That's if Device Manager
doesn't have any tick boxes for the hub that
explain the "snoozing" habits. It's not likely
that there are *any* outboard circuits of
significance. And even if a diode costs $0.05,
they'll still strip it out to hit the $7
price point for the retail price. I mean, they
didn't even add ballast to the thing, to make
it handle nicely. Some small electronics, use
a weight inside the chassis and rubber feet, to
improve handling on the desktop. So it doesn't
slide off quite as easily.

HTH,
Paul
  #3  
Old July 29th 18, 04:24 AM posted to microsoft.public.windowsxp.general
Bill in Co
external usenet poster
 
Posts: 1,927
Default USB 2.0 hubs?

Paul wrote:
Bill in Co wrote:
I bought two 4-port USB ports to extend one I have on the computer, and
they both work fine, but a bit differently. When I connected each one
to the computer, it naturally found the new hardware and installed a
driver, as expected. (I'm using Windows XP)

However, for one of these items, each time you plug a different USB
device into it, it needs to initially enumerate the device, but not so
for the other. The only difference I can tell on the specs is that one
is called a USB port hub splitter, and the other lacks that term
"splitter" (and that the first one appears to be a bit more advanced
(for example, allows for external power). Here are the two items. Can
someone explain why the difference in enumeration, and that one needs to
do it, while the other doesn't?


https://www.amazon.com/UGREEN-Splitt...ds=usb+2+ports


https://www.amazon.com/AmazonBasics-...=usb+2.0+ports


Items at that price point, aren't likely
to have screws for easy disassembly. More likely
to be glued together.

You can try to use USBTreeView to gather VID/PID, or
you can use Device Manager Properties and HardwareID
to do much the same thing.

https://www.uwe-sieber.de/usbtreeview_e.html

If the device had some sort of aggressive power
saving, maybe it sleeps and only a plug-in event
starts the enumeration process and bus resets.
You can check the Device Manager properties
and see if there is a tick box to stop it
from "sleeping".

*******

When you see a device with external power...

1) The power input connector may not be rated to carry enough
power to run all ports at full power. A barrel connector
might handle 3 to 5 amps on a good day (specs are available).
Other connectors might be 1 amp or so (before there is a
possibility of the pins burning). The barrel connector is the
right solution for this job.

2) A great many powered hubs from China, cut corners.

a) There is an app note from a famous chip company
that makes USB 4 port hub chips, that shows
how to do powering properly. When current
starts to flow into the external connector,
it operates a small relay. The small relay
disconnects VBUS from the PC, from the hub and
the hub outputs run off adapter power. No
"reverse flow", upsetting the ATX supply,
is possible with the relay design.

You may hear a "click" if using one of those.
But at $7 retail, nobody can afford a relay. The
relay costs more than all other parts and the PCB,
combined. Forget doing it right! A $35 hub can
probably afford to use a relay inside.

b) A silly design, could use diodes. This violates
the voltage drop spec for the bus. But might still
work anyway. The best Schottky diodes I could buy
for a home project, have a reasonably small drop
at low current. But once you pump an amp through
them, they're little better than regular diodes.
And of course, in a hub design, everyone treats
the power output capability, like the thing is
"Niagara Falls". Lots of reviewers are upset because
it's not charging their iPad.

c) Some designs will just short the hub power input
to VBUS, allowing the wall adapter to push current
into the ATX PSU. It might not catch fire, but
it might not be completely stable either. I don't
have a symptom list assembled for this possibility.

The notion of external power is nice, but the
engineers "went on vacation" when designing the
feature.

If you use semiconductors to do the power switching
and protect the PC, then there are all sorts of corner
cases to worry about (where the switch device starts
to half-conduct). I had at least one external
enclosure, with some pretty weird corner case
behavior from a power perspective (the LED would
light dimly when the device was "off").

At $7, that's only enough money for one USB chip,
and once you acquire enough info to get the part
number, you can then Google for "quirks" with
the part number in question. That's if Device Manager
doesn't have any tick boxes for the hub that
explain the "snoozing" habits. It's not likely
that there are *any* outboard circuits of
significance. And even if a diode costs $0.05,
they'll still strip it out to hit the $7
price point for the retail price. I mean, they
didn't even add ballast to the thing, to make
it handle nicely. Some small electronics, use
a weight inside the chassis and rubber feet, to
improve handling on the desktop. So it doesn't
slide off quite as easily.

HTH,
Paul


Thanks. I tried usbview but didn't glean all that much from it to explain
the difference as to why one hub cares about what's plugged in (installs a
new driver the first time it's used with a different USB device) and the
other doesn't, for some reason which I still haven't figured out. I'm
thinking it's because the UGreen one is acting more like an active hub, if
there is such a thing, and the Amazon is acting more like a passive one, and
for some reason doesn't care what's plugged into it (no new hardware icon
comes up). But I don't really understand all of this.


  #4  
Old July 29th 18, 07:29 AM posted to microsoft.public.windowsxp.general
Paul[_32_]
external usenet poster
 
Posts: 11,873
Default USB 2.0 hubs?

Bill in Co wrote:
Paul wrote:
Bill in Co wrote:
I bought two 4-port USB ports to extend one I have on the computer, and
they both work fine, but a bit differently. When I connected each one
to the computer, it naturally found the new hardware and installed a
driver, as expected. (I'm using Windows XP)

However, for one of these items, each time you plug a different USB
device into it, it needs to initially enumerate the device, but not so
for the other. The only difference I can tell on the specs is that one
is called a USB port hub splitter, and the other lacks that term
"splitter" (and that the first one appears to be a bit more advanced
(for example, allows for external power). Here are the two items. Can
someone explain why the difference in enumeration, and that one needs to
do it, while the other doesn't?


https://www.amazon.com/UGREEN-Splitt...ds=usb+2+ports


https://www.amazon.com/AmazonBasics-...=usb+2.0+ports

Items at that price point, aren't likely
to have screws for easy disassembly. More likely
to be glued together.

You can try to use USBTreeView to gather VID/PID, or
you can use Device Manager Properties and HardwareID
to do much the same thing.

https://www.uwe-sieber.de/usbtreeview_e.html

If the device had some sort of aggressive power
saving, maybe it sleeps and only a plug-in event
starts the enumeration process and bus resets.
You can check the Device Manager properties
and see if there is a tick box to stop it
from "sleeping".

*******

When you see a device with external power...

1) The power input connector may not be rated to carry enough
power to run all ports at full power. A barrel connector
might handle 3 to 5 amps on a good day (specs are available).
Other connectors might be 1 amp or so (before there is a
possibility of the pins burning). The barrel connector is the
right solution for this job.

2) A great many powered hubs from China, cut corners.

a) There is an app note from a famous chip company
that makes USB 4 port hub chips, that shows
how to do powering properly. When current
starts to flow into the external connector,
it operates a small relay. The small relay
disconnects VBUS from the PC, from the hub and
the hub outputs run off adapter power. No
"reverse flow", upsetting the ATX supply,
is possible with the relay design.

You may hear a "click" if using one of those.
But at $7 retail, nobody can afford a relay. The
relay costs more than all other parts and the PCB,
combined. Forget doing it right! A $35 hub can
probably afford to use a relay inside.

b) A silly design, could use diodes. This violates
the voltage drop spec for the bus. But might still
work anyway. The best Schottky diodes I could buy
for a home project, have a reasonably small drop
at low current. But once you pump an amp through
them, they're little better than regular diodes.
And of course, in a hub design, everyone treats
the power output capability, like the thing is
"Niagara Falls". Lots of reviewers are upset because
it's not charging their iPad.

c) Some designs will just short the hub power input
to VBUS, allowing the wall adapter to push current
into the ATX PSU. It might not catch fire, but
it might not be completely stable either. I don't
have a symptom list assembled for this possibility.

The notion of external power is nice, but the
engineers "went on vacation" when designing the
feature.

If you use semiconductors to do the power switching
and protect the PC, then there are all sorts of corner
cases to worry about (where the switch device starts
to half-conduct). I had at least one external
enclosure, with some pretty weird corner case
behavior from a power perspective (the LED would
light dimly when the device was "off").

At $7, that's only enough money for one USB chip,
and once you acquire enough info to get the part
number, you can then Google for "quirks" with
the part number in question. That's if Device Manager
doesn't have any tick boxes for the hub that
explain the "snoozing" habits. It's not likely
that there are *any* outboard circuits of
significance. And even if a diode costs $0.05,
they'll still strip it out to hit the $7
price point for the retail price. I mean, they
didn't even add ballast to the thing, to make
it handle nicely. Some small electronics, use
a weight inside the chassis and rubber feet, to
improve handling on the desktop. So it doesn't
slide off quite as easily.

HTH,
Paul


Thanks. I tried usbview but didn't glean all that much from it to explain
the difference as to why one hub cares about what's plugged in (installs a
new driver the first time it's used with a different USB device) and the
other doesn't, for some reason which I still haven't figured out. I'm
thinking it's because the UGreen one is acting more like an active hub, if
there is such a thing, and the Amazon is acting more like a passive one, and
for some reason doesn't care what's plugged into it (no new hardware icon
comes up). But I don't really understand all of this.


This is one of the informal lists of USB devices.
Your USB software tool (or Device Manager) should have
two four digit hex numbers for vendor and device.

http://www.linux-usb.org/usb.ids

I don't think there is a distinction on hubs.
The hub interacts from a protocol perspective.
It reclocks the data and the time to reclock
the information is part of the overall USB
time budget. The time budget limits operation
to a tree depth of five hubs or so. On modern
motherboards, Intel added a hub to the PCH,
limiting the user to four external hubs
in a row. You can hit that limit if using
one-port ("active") USB extension cables.

A powered hub and an unpowered hub, just differ
on where VBUS comes from. An unpowered hub has
a limitation on what the subtending devices can
draw. I was surprised though, at what kind of
loads you could run on USB extension cables
(which are unpowered), as I was able to run
a webcam with focus motor off the end of
three cables. I was expecting to only be
able to run a USB keyboard off the (reclocked)
cable chain.

The address limit on USB is 127 devices and
I presume the hub itself has an address. I don't
know if USB3 attempted to change these limits
at all or not. Some aspect of polling may have changed
on USB3, and electrically, USB3 (the 5 pin wiring
portion) is full duplex.

USB3 includes a high speed section (full duplex)
and the low speed USB2 portion (half duplex). While
the two interfaces could be used to move data
at the same time, software limits operation to
the negotiated interface.

TX+ \
TX- \
GND \__ USB3 rate portion
RX+ /
RX- /

VBUS \
D+ \___ USB2/UWB1.1 legacy portion
D- /
GND /

Paul

 




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