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25 votes
Accepted

How does a USB Hub work?

It's all to do with arbitration. Any system which requires multiple devices to be connected needs some way of determining who should talk when. There are different schemes as you would expect ...
Tom Carpenter's user avatar
13 votes
Accepted

USB hub: What's the use of the 0.1 μF capacitors in series with the RX connections?

They are not there just to block the DC, but also meet the impedance requirements. You want the diff pairs between the transmitter and the receiver to be coupled properly. RX lines don't have the AC ...
Rohat Kılıç's user avatar
13 votes
Accepted

USB 3 hub is fried! why? room for improvement?

This is the most bad-quality modern computer electronics PCB I have ever seen. And I've seen some fecal matter. This is the fecaliest matter of all. This board should have been rejected at the factory,...
Marcus Müller's user avatar
9 votes
Accepted

Is there an advantage to using 12V vs 5V for a powered USB hub design?

For hubs with large numbers of ports, the current required at 5v would be impractically high and so higher voltage is usually required. These will usually integrate 1 or more buck converters to step ...
user1850479's user avatar
  • 17.3k
8 votes

Can I Build My Own USB Hub?

Sure, I do it all the time — custom hubs for embedded applications. I use chips from Cypress, but they're certainly not the only game in town. You do need to pay careful attention to the layout ...
Dave Tweed's user avatar
  • 174k
7 votes

USB hub: What's the use of the 0.1 μF capacitors in series with the RX connections?

USB3 signals are AC coupled so the DC needs to be removed with capacitors.
Justme's user avatar
  • 154k
6 votes
Accepted

What does the USB non-removable strap option actually change?

The information about whether a port is "removable" or not serves mostly the purpose of hub/device (compound device) certification. When the USB compliance software runs, it will check for various ...
Ale..chenski's user avatar
  • 40.9k
6 votes

How can I add additional components and connections to make this USB hub functional?

The datasheet of this particular chip lacks several design details that you can find in the FE2.1 datasheet, which is from the same family of products but offers 7 downstream USB ports. Now then, as ...
Chame's user avatar
  • 61
6 votes

Does the Microchip/SMSC PHYBoost technology help with Rx, or does it boost Tx only?

From the datasheet, the only reference I can see to PHYBoost is: PHYBoost which enables four programmable levels of USB signal drive strength in USB port transceivers That indicates that basically ...
Tom Carpenter's user avatar
5 votes

Can I Build My Own USB Hub?

With some usb hub ICs it's as simple as the ic, a crystal, and a few passive components. Easy to design if you feel like taking the time. A single sided PCB is possible too. Here's a simple (two-...
Passerby's user avatar
  • 73.2k
5 votes

LAN9500A Ethernet Adapter

The major mistake in your schematics is that the nRESET signal (pin 24) doesn't follow the delay specifications. The deassertion of this signal must be delayed until all supply voltages reach valid ...
Ale..chenski's user avatar
  • 40.9k
5 votes
Accepted

Why does my bus-power-only USB hub enumerate as self-powered?

The tactics of presenting a bus-powered hub as "self-powered" is a standard cheating practice. The reason most manufacturers do this is that a certifiable bus-powered hub must have (a) power ...
Ale..chenski's user avatar
  • 40.9k
5 votes
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Purpose of this IC in USB 3.0 Hub

You need the mux to handle the case of plugging in the USB-C cable in either direction. The super speed pin pairs are only wired to one side of the connector, so your circuitry must figure out which ...
td127's user avatar
  • 3,126
4 votes

USB 3.0 Hub shield connection

It all depends on device construction, whether you have hot plug options, whether the device has exposed metal connections to electronic internals and possible ESD events, or whether your primary ...
Ale..chenski's user avatar
  • 40.9k
4 votes

Can I Build My Own USB Hub?

I have done this using TUSB4041I but had to use a professional assembly house to populate the board, it is incredibly fiddly.
beerbug's user avatar
  • 85
4 votes

A rather big (28 ports) USB hub design consultation

There are plenty of 28+ port hubs on the market, "Manhattan", ORICO industrial grade, and even 97-port hub with 400W power supply. All multi-port hubs are built hierarchically out of 7-port hubs and ...
Ale..chenski's user avatar
  • 40.9k
4 votes

USB2517 USB hub unable to enumerate

I'd recommend for you to always read the datasheet of the IC you are designing a circuit for, you can NOT send your design for fab without scrubbing through every little detail. Also, take a look at ...
eeintech's user avatar
  • 956
4 votes

Is 5.5V safe for USB storage devices?

According to USB-IF updates, "USB 2.0 VBUS Max Limit ECN as of August 11, 2014", the allowed VBUS voltage is now 5.5V. See latest release of USB 2.0 specification with all ECNs. Old poorly-...
Ale..chenski's user avatar
  • 40.9k
4 votes

Do I need to switch power and ground on USB 3.0?

You can't get away with that at all. USB3 has bandwidth that require special switches to maintain the impedance. So, no matter what, "switch in the data line" is a bad idea, and should not ...
Marcus Müller's user avatar
4 votes
Accepted

Do I need to switch power and ground on USB 3.0?

OPTION 1 - DO IT IN SOFTWRE If you can find the documentation for the upstream hub. There should be a command you can send the hub to turn off a downstream device via software. You can then avoid ...
user4574's user avatar
  • 12.3k
4 votes
Accepted

Replacing USB251xB/xBI USB 2.0 HUB Controller

The best people to ask are the Microchip application engineers. That's kinda their entire purpose of existing. There will be a 'contact' button on their website.
Kyle B's user avatar
  • 4,608
4 votes
Accepted

Why does the USB specification have 3 different system power configurations?

A bus-powered hub can't provide the full rated power to multiple downstream ports at once, without exceeding the power limits of the bus that's powering the hub. If the hub is powered by a USB 2.0 ...
Hearth's user avatar
  • 33.8k
4 votes
Accepted

Computer interface with USB devices

That's not how it works. Your computer will only see the STM32 in which ever way you like. For example a virtual serial port per submodule. Then you need to make the STM32 software which can provide ...
Justme's user avatar
  • 154k
3 votes

Properly route through hole USB-C

Just by looking quickly at your traces and vias, I have found 4 vias that are unnecessary. Here they are: You are switching between bottom and top layer twice instead of staying on the top layer. ...
12Lappie's user avatar
  • 1,401
3 votes
Accepted

Is the self-powered USB hub powering my devices?

The simplest way to know if your hub is providing power to the ports or not is to just plug something into it while it's not connected to the computer. If it gets power then the only place it can ...
Majenko's user avatar
  • 56.3k
3 votes

Do I need USB isolator for laptop computer?

I suggest you consider isolating the RS-232 as @Ignacio suggests. You can even buy a packaged single-chip solution that actually includes internal transformers for signal and power isolation: A USB ...
Spehro Pefhany's user avatar
3 votes
Accepted

Wiring of USB 2.0 hub using a USB-C connector

Your computer does not see your device/hub because the CC1 (communication channel) pin A5 is not wired (or wired incorrectly). For the cable to be recognized as a device/hub, the CC1 pin must be ...
Ale..chenski's user avatar
  • 40.9k
3 votes
Accepted

How can I build a micro USB hub?

All these y splitters are, are a usb hub ic, a few passives, and the usb ports. It is an active device, not just wires. Some all in one USB hubs like GL850G are used. You could get a cheap dollar hub ...
Passerby's user avatar
  • 73.2k
3 votes
Accepted

Are USB 2.0 hubs required to disable downstream VBUS when upstream VBUS is removed

External power in case of hubs refers to external power adapter (or even a battery). If this is the only power to the hub, and it is a solo source of Vcc for hub controller IC, then it is obvious that ...
Ale..chenski's user avatar
  • 40.9k
3 votes

What is the difference between usb root hub and usb host controller?

A regular USB hub is a USB device that can split USB traffic from one (upstream) link to several downstream ports, and mux the upcoming traffic from many ports into one upstream. To do so, each hub ...
Ale..chenski's user avatar
  • 40.9k

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