USB over Ethernet

[Aelita Sophie]

Ok, so before you start, yes there are plenty of solutions available for the right amount of money. Non of them either look really promising to me, or are frankly just to expensive.

So basically, I've got my Gaming rig in a server cabinet in a different room. I'm already using HDMI over ethernet with just one screen not really liking it, but this is most likely due the use of CAT5e instead of CAT6a, so I'll be replacing that cable soon.

I'm trying to push USB over an ethernet cable as well, so I can use a keyboard, mouse, small usb audio device (havent really chosen one yet) and my Samson G-Track mic. The length will be about 6 meters or about 20ft. I've got a 5 meter USB extention cable, which works perfectly to spec (full USB2.0 speeds), but I sadly cant run those through the wall. I purchased some cheap USB to Ethernet adapters from Aliexpress and they work to a certain extend. I'm only getting 2.1mb/s regardless of cable length or type. (Tried 6 meters and even 1 meter, CAT5e and CAT6a) Also it seems to drop the connection every now and then. I opened this thing up, to see what components its using, but they used a black blob to hide it.

 

I've tried to design my own PCB for this, but I'm concerned about the D+/- lines not holding out the 6 meter length. I've got no idea what chip to use for this to either boost this in a similar fashion as the cheap chinese converter does. (Al being a "better" chip for better speeds). Can someone hint me to the right direction?

 

The USB to Ethernet adapters from china:

 

The PCB Design I've got so far:

 

[Windows7ge]

I don't think Cat5e vs Cat6a is going to make much if any of a difference unless you're dealing with a interference issue in which case you'd want a STP cable instead of UTP. Cat6A can push 10Gbit but inless the adapter on the computer is capable of it then I don't think it'll change anything.

 

Linus made a video quite some time back where they used a fiberoptic cable and a dongle like base that had usb ports/ display ports among other ports. The cable & base were expensive though. It did work with little latency though. I can't recall the specifics. Maybe someone can link the video. It's when he built his 4U server chassis desktop and wanted it in another room.

[Aelita Sophie]

21 minutes ago, Windows7ge said:

I don't think Cat5e vs Cat6a is going to make much if any of a difference unless you're dealing with a interference issue in which case you'd want a STP cable instead of UTP. Cat6A can push 10Gbit but inless the adapter on the computer is capable of it then I don't think it'll change anything.

 

Linus made a video quite some time back where they used a fiberoptic cable and a dongle like base that had usb ports/ display ports among other ports. The cable & base were expensive though. It did work with little latency though. I can't recall the specifics. Maybe someone can link the video. It's when he built his 4U server chassis desktop and wanted it in another room.

I've seen that video, but that solution will cost several hundred euro's. I'm only concerned if the databus can reach the end of the cable. As the chinese converter shows, it probably has a chip underneath that black blob. I just want to know a microchip like that, with better performance as stated in my OP. Ideally with some examples for deploying such chip.

[WereCatf]

@Aelita SophieHow about just buying a powered USB-cable instead? I have no personal experience with these, but something along the lines of e.g. https://www.amazon.co.uk/TRIXES-Extension-Cable-Active-Repeater/dp/B004S67QR2 seems like it should work and it'd be easier and cheaper than coming up with a custom design or using ethernet to carry USB.

[Windows7ge]

4 hours ago, Aelita Sophie said:

I've seen that video, but that solution will cost several hundred euro's. I'm only concerned if the databus can reach the end of the cable. As the chinese converter shows, it probably has a chip underneath that black blob. I just want to know a microchip like that, with better performance as stated in my OP. Ideally with some examples for deploying such chip.

To my knowledge it's a practice known as chip on board. It's a silicon die that is dead-bug mounted to the PCB by EXTREMELY thin gold bonding wires. It's then covered by a black goop that solidifies and holds everything in place. These are typically custom chips which are spun up for a specific application. They also cover it in goop in an attempt to keep people from looking at it, reverse engineering it, & ripping it off.

[Aelita Sophie]

19 minutes ago, WereCatf said:

@Aelita SophieHow about just buying a powered USB-cable instead? I have no personal experience with these, but something along the lines of e.g. https://www.amazon.co.uk/TRIXES-Extension-Cable-Active-Repeater/dp/B004S67QR2 seems like it should work and it'd be easier and cheaper than coming up with a custom design or using ethernet to carry USB.

I cant push a wire like that through the electrical plumbing. It can hold about 3 ethernet cables, obviously without the RJ45 connectors on it.

 

3 minutes ago, Windows7ge said:

To my knowledge it's a practice known as chip on board. It's a silicon die that is dead-bug mounted to the PCB by EXTREMELY thin gold bonding wires. It's then covered by a black goop that solidifies and holds everything in place. These are typically custom chips which are spun up for a specific application. They also cover it in goop in an attempt to keep people from looking at it, reverse engineering it, & ripping it off.

Alright, but I cant really imagine that it would be hard to get a microchip of some sorts who can boost the databus signal to a certain extend. For example https://lcsc.com/product-detail/USB_CH9326_C77683.html (unsure if this is the right microchip kind) has a 12Mbps transfers rate.

[Windows7ge]

4 hours ago, Aelita Sophie said:

Alright, but I cant really imagine that it would be hard to get a microchip of some sorts who can boost the databus signal to a certain extend. For example https://lcsc.com/product-detail/USB_CH9326_C77683.html (unsure if this is the right microchip kind) has a 12Mbps transfers rate.

If you can seup your own signal/voltage amplifier circuit that's great. I'm just saying there are manufacturers that think their custom chips are "special snowflakes" and still don't want people copying them regardless of how simple the chip really is.

 

Why do you want the machine far away to begin with? Are you using server fans?

[Aelita Sophie]

1 minute ago, Windows7ge said:

If you can seup your own signal/voltage amplifier circuit that's great. I'm just saying there are manufacturers that think their custom chips are "special snowflakes" and still don't want people copying them regardless of how simple the chip really is.

 

Why do you want the machine far away to begin with? Are you using server fans?

Well, thats because I want my gaming/office room to be as silent as I can and also remove the heat from the room. And yes in this case I am using server fans. I transplanted the guts into a 4U server case. Though I'm not exactly wealthy, I'm pretty much at the lower end of that. I love tinkering around however, so attempting to design a PCB (something I haven't done before) is great fun to me. As far as those pricing goes, its doable.

[WereCatf]

10 minutes ago, Aelita Sophie said:

I cant push a wire like that through the electrical plumbing. It can hold about 3 ethernet cables, obviously without the RJ45 connectors on it.

I suppose you'd have to cut off/desolder the USB-connector on the other end, then push the cable through and replace the connector. If you're capable of designing your own PCBs, I would imagine you being able to do that as well, though I don't know if that's something you'd be willing to do. It'd still be the easiest route I can think of.

[Windows7ge]

Well, good luck. I don't really have much more help to offer. If you room opposes another room you could run cables though the wall and run everything like that. No signal booster required.

[Blebekblebek]

I'm trying to understand this.

 

So you want to run USB more than 5m correct?

You've done so with an adapter and so far it worked but with limited speed (and drops often)

 

Personally I've done it with regular usb extender with about 10m and it's working fine (it was for USB Wifi adapter)

 

My question is, why you need an adapter?

Have you tried direct connect like in this video?

If it's still drops often it could be boosted with Active USB hub (HUB with power adapter)

[Aelita Sophie]

9 minutes ago, Blebekblebek said:

I'm trying to understand this.

 

So you want to run USB more than 5m correct?

You've done so with an adapter and so far it worked but with limited speed (and drops often)

 

Personally I've done it with regular usb extender with about 10m and it's working fine (it was for USB Wifi adapter)

 

My question is, why you need an adapter?

Have you tried direct connect like in this video?

If it's still drops often it could be boosted with Active USB hub (HUB with power adapter)

Well good question... I might just be over engineering this.. Putting it like that, how I've got the PCB designed right now, should work fine. (Just for a neat solution, as it allows me to hook up 2 usb ports and even a powerrail if needed)

 

Have you tested the dataspeeds? I don't need full USB2.0 specs, but those adapters are abysmal. Anything half-way the USB2.0 specs would be great! Because considering the adapters I've got right now. Keyboard + mouse would be fine, but adding a mic, usb audio and an occasional USB-Stick would not work out. Because with those data-rates it would be pushing it very hard.

[Aelita Sophie]

16 minutes ago, Windows7ge said:

Well, good luck. I don't really have much more help to offer. If you room opposes another room you could run cables though the wall and run everything like that. No signal booster required.

This is pretty much where it goes through

 

 

[Unimportant]

7 hours ago, Aelita Sophie said:

but they used a black blob to hide it.

 

7 hours ago, Aelita Sophie said:

Can someone hint me to the right direction?

The chip is probably a differential repeater/buffer/redriver - whatever marketing calls it.

Note that the black blob is not meant to hide things persé. It's a method of attaching the die straight to the PCB without packaging the chip. The resin blob then protects the chip. It's a ultra cheapskate way of doing things.

 

As for your PCB design for a straight USB to Ethernet cable adapter: Cat5E has a characteristic impedance of 100 ohm. USB's is 90 ohm. So perhaps that's close enough and might work.

 

The PCB design might require more care regarding impedance matching. Take a look at this page http://www.electronic-products-design.com/geek-area/electronics/pcb-design/general-pcb-design/pcb-track-impedance  under "USB 90ohm Differential Pair Track Impedance"

 

After that it's up to the parasitic properties of the cable (listed in a table here: https://en.wikipedia.org/wiki/Category_5_cable ) mainly capacitance and inductance per meter to decide if things will work over distance or not. 

 

Make sure you use a differential pair inside the Ethernet cable for the D+ and D-

 

[SasaKaranovic]

If you want to go full custom check something like https://www.microchip.com/wwwproducts/en/LAN7500 and you can go as far as you want.

 

I haven't used it but assuming you put one of these on each end you should get (a very expensive) USB-to-ETH-to-USB.

 

Using CAT5 or CAT6 cables and just pushing D+ and D- through them won't offer you any great advantage since impedance (resistance)

of your wires will eventually become so high that controller on the receiving side won't be able to use incoming signal.

[Aelita Sophie]

7 hours ago, ColdKeyboard said:

If you want to go full custom check something like https://www.microchip.com/wwwproducts/en/LAN7500 and you can go as far as you want.

 

I haven't used it but assuming you put one of these on each end you should get (a very expensive) USB-to-ETH-to-USB.

 

Using CAT5 or CAT6 cables and just pushing D+ and D- through them won't offer you any great advantage since impedance (resistance)

of your wires will eventually become so high that controller on the receiving side won't be able to use incoming signal.

Cant give exact measurements, as my equipment is very cheap. (Multimeter was like €5) But I'm measuring about 1.2 Ohm over a length of 6 meters.

[Unimportant]

1 hour ago, Aelita Sophie said:

Cant give exact measurements, as my equipment is very cheap. (Multimeter was like €5) But I'm measuring about 1.2 Ohm over a length of 6 meters.

That is DC resistance, which is irrelevant. What we're talking about is impedance - reactive resistance - caused by the interaction of reactive parasitic elements (inductance and capacitance) of the wire and the high frequency signals present in any digital square wave signal.

The sharp edges of a square wave are made up of high frequency harmonics on odd multiples of the fundamental frequency (theoretically infinite), the impedance will resist these high frequencies. This "dulls" the edges of the square wave, so it no longer looks like a square wave. Too much and the receiver will no longer recognize the signal.

 

Another problem are transmission line effects, mainly reflections. At such high frequencies, the output impedance of the transmitter, the  input impedance of the receiver and the characteristic impedance of the connection between them (cables, connectors, PCB traces) must match ("impedance matching"). Otherwise the signal will reflect. The reflected signal will interact with the actual signal, again causing signal corruption. That's why I said the PCB design might need more work, you need to get as close as possible to the 90ohms impedance USB requires on your PCB. On top of that USB is a differential signal, differential pairs must also be laid out with certain practices in mind such as length matching, etc.

If you've ever wondered why the traces going to the PCI express slots on a motherboard are laid out in groups of 2, close to one another, with traces sneaking around to match lengths - those are the differential pairs.

[Aelita Sophie]

1 hour ago, Unimportant said:

That is DC resistance, which is irrelevant. What we're talking about is impedance - reactive resistance - caused by the interaction of reactive parasitic elements (inductance and capacitance) of the wire and the high frequency signals present in any digital square wave signal.

The sharp edges of a square wave are made up of high frequency harmonics on odd multiples of the fundamental frequency (theoretically infinite), the impedance will resist these high frequencies. This "dulls" the edges of the square wave, so it no longer looks like a square wave. Too much and the receiver will no longer recognize the signal.

 

Another problem are transmission line effects, mainly reflections. At such high frequencies, the output impedance of the transmitter, the  input impedance of the receiver and the characteristic impedance of the connection between them (cables, connectors, PCB traces) must match ("impedance matching"). Otherwise the signal will reflect. The reflected signal will interact with the actual signal, again causing signal corruption. That's why I said the PCB design might need more work, you need to get as close as possible to the 90ohms impedance USB requires on your PCB. On top of that USB is a differential signal, differential pairs must also be laid out with certain practices in mind such as length matching, etc.

If you've ever wondered why the traces going to the PCI express slots on a motherboard are laid out in groups of 2, close to one another, with traces sneaking around to match lengths - those are the differential pairs.

I can hardly call myself even a novice within this kind of work. I simply doodle a bit and hope for the best. I have no clue how to measure impedance, how would I do such thing?

[Unimportant]

8 hours ago, Aelita Sophie said:

I have no clue how to measure impedance, how would I do such thing?

One uses a function generator to generate a sine wave of the desired frequency and sends it trough the device to test, in this case the cable (properly terminated). One can then use a oscilloscope to observe the signal coming out on the other end. By seeing the amount of attenuation one can calculate the impedance. A device that does the whole thing in one go is called a network analyzer.

 

That's pretty expensive equipment and unfeasible for a one-off project. Imho, the most cost-effective solution is to just try it under the best possible conditions: Find yourself a USB connector and plug for DIY attachment to a cable:

( https://www.adafruit.com/product/1387    https://www.adafruit.com/product/1388 )

Solder these connectors straight to a piece of the network cable you're planning to use of the desired length, use a twisted pair for D+ and D-. Soldering the connectors straight to the cable causes the least amount of "intrusion". If it works then you should be able to make it work with a well designed adapter PCB aswell. If it does not work then there's no chance the adapter PCB will work either.

 

[mariushm]

Search Amazon and other stores for  ACTIVE usb cable , they're cables which have on both ends some chips... one end amplifies the signal that goes through the usb cable to allow for longer distances and on the other end you may have on the cable the receiver which produces usb compatible signal. 

So no need for any fancy stuff, just install the usb cable through the wall. In the back of your computer or whatever, plug the usb cable into a usb hub and you have multiple usb connectors.

 

Here's examples of such cables:

 

15$: AmazonBasics USB 2.0 Active Extension Cable Type A-Male to A-Female - 32 Feet (9.75 Meters)   https://amzn.to/2K2COMx

 

8.5$ : Monoprice 16ft 5M USB 2.0 A Male to A Female Active Extension / Repeater Cable use with PlayStation, Xbox, Kinenct, Oculus VR, USB Flash Drive, Card Reader, Hard Drive, Keyboard, Printer, Camera and More!  : https://amzn.to/2AhGavp

13.15$  same as above but 32ft (~10m): https://amzn.to/2uUBOp6

 

16$: Plugable 10 Meter (32 Foot) USB 2.0 Active Extension Cable Type A Male to A Female : https://amzn.to/2uTL9NI

(only ~5m) 13$: CableCreation (Long 16FT) Super Speed Active USB 3.0 Extension Cable, USB 3.0 Extender USB Male to Female Repeater Cable with Signal Booster for Oculus Rift,Xbox,PS4 and more, Black : https://amzn.to/2K48ukD

 

Most of the above have a female connector at the end, you can just buy a very short half a meter or something like that  usb male - usb male cable so that you can plug the end into a usb hub to get more usb connectors.

 

There's also more expensive USB over ethernet, for example this one at 50$ .. but I think it's overkill for your needs :

 

WEme USB 2.0 Extender to RJ45 Over Cat5/5E/6 Connection up to 100 Meter/328 Ft Ethernet Extention Cable Type A Male to A Female with 5V/2A Power Adapter  : https://amzn.to/2LEIyRF

 

And if you really want to you can spend 100$+ to buy super thin fiber based usb cable:

Corning Optical Cables by USB 3.0 Optical Cable 10 Meter (32.8') : https://amzn.to/2K1lFD4

 

This one only transfers DATA through it, so you NEED a POWERED usb hub/switch (not a switch or hub that's powered from the usb cable) to send data through the cable, and to push power in the other connectors that go to your devices. It won't work to connect a keyboard or mouse directly to the optical usb cable because there's no power coming through it.

 

[r4tch3t]

Lots to read so not sure if it's been mentioned. Buy a powered USB cable that you cut the ends off and rewire with ethernet cable?