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NormanDunbar
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Don't but this USB hub

Fri Aug 24, 2012 1:51 pm

Greetings.

I purchased a Dynamode USB Hub for use with my Pi. It's a 7 port self powered HUB. The hub is the same as those being sold at Farnells as being compatible with the Pi. (http://uk.farnell.com/dynamode/usb-h70- ... dp/2115058 is the URL for the hub).

The hub claims to be USB 2.0 Standards compliant but is not for the following reasons:

1. It feeds power back up the interconnect to the Pi. Section 7.2.1 of the standard says that "No device shall supply (source) current on VBUS at its upstream facing port at any time. From VBUS on its upstream facing port, a device may only draw (sink) current."

2. It should supply 500 mA to each of the 7 USB ports, but the power supply is only rated at 5V 1000 mA in total. For a 7 port hub, it should be rated at 3.5 A I would imagine. As Section 7.2.1 says, "Hubs that obtain operating power externally must supply five unit loads [500 mA] to each port."

I've sent mine back for the above reasons, plus, it doesn't work with the Pi. I'm not sure Farnells should be selling this hub as being compatible with the Raspberry Pi. (Plus, the pdf download with the Hub specs is for a completely different hub!)

Other problems I have found with this hub in testing it are:

1. The power back feed as mentioned above.

2. With the interconnect cable disconnected, it cannot even power the Pi!

3. With the hub connected, the Pi will not boot.

4. Booting the Pi, and connecting the hub causes the network to stop working.

5. The power lead is about 45 cm/18" long.

6. So is the interconnect cable.

All in all, not a good buy - other than good by to my postage and packing for sending it back. :-(



Cheers,
Norm.
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Jim JKla
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Re: Don't but this USB hub

Fri Aug 24, 2012 1:54 pm

Good feedback. Even if the Hub was giving bad feedback ;)
Noob is not derogatory the noob is just the lower end of the noob--geek spectrum being a noob is just your first step towards being an uber-geek ;)

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NormanDunbar
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Re: Don't buy this USB hub

Fri Aug 24, 2012 2:21 pm

Hi Jim,

I did think of opening it up and fitting a diode to prevent the power back feed from the interconnect cable, but then I figured, it's so small it's most likely a PCB mounted USB socket and anyway, the other problems with it render it useless anyway, so why bother. It's going back.

Cheers.
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Why did Tarzan never have a beard?

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RaTTuS
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Re: Don't but this USB hub

Fri Aug 24, 2012 2:44 pm

there are a lot of those going round amazon / ebay also
I have 4 - and they all work with my RPi's though I know other people who cannot get them to work
they do back power the RPi
the sockets are all pcb mounted
I've opened mine up and have removed several sockets on one so I can wire some sockets in as cables [which work]
they have 2 chips which say :-
FE1.18
usb2.0
LG33344B6172C

Bus 001 Device 004: ID 05e3:0610 Genesys Logic, Inc. 4-port hub
Bus 001 Device 005: ID 05e3:0610 Genesys Logic, Inc. 4-port hub
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX
Covfefe

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NormanDunbar
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Re: Don't but this USB hub

Fri Aug 24, 2012 2:58 pm

RaTTuS wrote:I have 4 - and they all work with my RPi's though I know other people who cannot get them to work
Interesting. What power rating is the power supply then? Maybe you got lucky and have one with enough power to work.
RaTTuS wrote:Bus 001 Device 004: ID 05e3:0610 Genesys Logic, Inc. 4-port hub
Bus 001 Device 005: ID 05e3:0610 Genesys Logic, Inc. 4-port hub
That's exactly what lsusb says about mine as well.

Cheers.
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drgeoff
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Re: Don't but this USB hub

Fri Aug 24, 2012 3:28 pm

NormanDunbar wrote: All in all, not a good buy - other than good by to my postage and packing for sending it back. :-(
Norm.
I think you have adequate grounds for demanding a refund of your return postage.

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NormanDunbar
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Re: Don't buy this USB hub

Fri Aug 24, 2012 3:31 pm

drgeoff wrote:I think you have adequate grounds for demanding a refund of your return postage.
You may be correct, however, it wasn't advertised as being compatible with the Pi, and the company I bought it from, like Farnells, probably don't have time or skills to test everything that all their products claim to be/do.

Besides, the company is actually quite local to where I live - they are in Bradford - so I'll be up that way over the weekend, so I can return it in person.

Equally, they haven't said I won't get my postage refunded .....

We shall see.


Cheers,
Why do they put lightning conductors on churches?
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RaTTuS
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Re: Don't but this USB hub

Fri Aug 24, 2012 3:42 pm

NormanDunbar wrote:
RaTTuS wrote:I have 4 - and they all work with my RPi's though I know other people who cannot get them to work
Interesting. What power rating is the power supply then? Maybe you got lucky and have one with enough power to work.
RaTTuS wrote:Bus 001 Device 004: ID 05e3:0610 Genesys Logic, Inc. 4-port hub
Bus 001 Device 005: ID 05e3:0610 Genesys Logic, Inc. 4-port hub
That's exactly what lsusb says about mine as well.

Cheers.
2000mA
PSU's
which is not enough to power all @500mA obviously, but easily enough to power the RPi' and a HD + keyboard + mouse
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

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drgeoff
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Re: Don't buy this USB hub

Fri Aug 24, 2012 3:43 pm

NormanDunbar wrote:You may be correct, however, it wasn't advertised as being compatible with the Pi, and the company I bought it from, like Farnells, probably don't have time or skills to test everything that all their products claim to be/do.
You are not returning it because of not being compatible with the RPi. You are returning it because it is not fit for purpose as a USB hub - as per the USB specs you quoted.

That the seller doesn't test products is a risk that should be borne by the seller, not the purchaser.

fredjam
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Re: Don't but this USB hub

Sat Aug 25, 2012 1:49 am

I have a really cheap 7 port usb hub bought on ebay. It claims to have a 2.5 amp power supply.
I have cut the +5 volt track on the B terminal output so that it can't feed power back to the pi.
I use it to power the pi, my trackball and keyboard, a usb hdd and a memory stick without
problems.

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NormanDunbar
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Re: Don't but this USB hub

Sat Aug 25, 2012 11:51 am

RaTTuS wrote:2000mA PSU's which is not enough to power all @500mA obviously, but easily enough to power the RPi' and a HD + keyboard + mouse
This is true, but yours are twice as powerful as mine. I've only got 1000 mA.

Never mind, took it back this morning for a complete refund. The man asked why, so I told him! They noted it down on the system and maybe, something will be done. However, Farnells are still selling them as Pi compatibles - which they might be, if they were fixed!

Cheers.
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reggie
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Re: Don't but this USB hub

Sat Aug 25, 2012 1:17 pm

I'm actually pretty disgusted with farnell that they sell those usb hubs, they come under many names but as has been pointed out, they use the FE1.X chips, they're hard wired to show up as externally powered, they usually have missing caps on the usb sockets, you get 5v backwash down the vUsb due to missing diode and there is probably a missing cap on the 5V input somewhere too. Then of course there is the power supply, your mileage will vary as to whether you got a decent 2amp psu or a fire hazard.

I didn't buy my hub from farnell, I bought it cheap off ebay, so I knew it was cheap and cheerful when I bought it, I took it apart the day I got it, so it has never ever been plugged into my pi, nor will it ever get plugged into it until I can get a diode across the V-usb line.

simplesi
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Re: Don't but this USB hub

Sat Aug 25, 2012 1:34 pm

I think a lot of us are quite happily using cheap/clones/this actual one :)

If I'd paid a lot of money for one, then I'd be complaining but I didn't and it works so I'm happy.

Maybe one day I'll find that any of the little issues I have with my RPi were down to using this hub but if you can one with a few quid its a bargain

Simon
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reggie
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Re: Don't but this USB hub

Mon Aug 27, 2012 2:20 pm

simplesi wrote:I think a lot of us are quite happily using cheap/clones/this actual one :)

If I'd paid a lot of money for one, then I'd be complaining but I didn't and it works so I'm happy.

Maybe one day I'll find that any of the little issues I have with my RPi were down to using this hub but if you can one with a few quid its a bargain

Simon
Good for you, I hope it goes well and doesn't burn your house down or fry your hardware :)

simplesi
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Re: Don't but this USB hub

Mon Aug 27, 2012 4:19 pm

I wondered what the burning smell was :eek:
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NormanDunbar
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Re: Don't but this USB hub

Tue Aug 28, 2012 8:16 am

reggie wrote:Then of course there is the power supply, your mileage will vary as to whether you got a decent 2amp psu or a fire hazard.
Morning Reggie. Even a 2 A PSU is underpowered for a 7 port USB hub. There should be, according to the USB 2.0 Standard, 500 mA on each port - so a minimum of 3.5 A would be required to be standards compliant. 2 A would only suffice for a 4 port hub.

Cheers.
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Jim JKla
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Re: Don't but this USB hub

Tue Aug 28, 2012 8:28 am

Point of information
My 7 port Belkin F5U010 was supplied with a 6v 4a PSU ;)
Noob is not derogatory the noob is just the lower end of the noob--geek spectrum being a noob is just your first step towards being an uber-geek ;)

If you find a solution please post it in the wiki the forum dies too quick

reggie
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Re: Don't but this USB hub

Tue Aug 28, 2012 10:26 am

NormanDunbar wrote:
reggie wrote:Then of course there is the power supply, your mileage will vary as to whether you got a decent 2amp psu or a fire hazard.
Morning Reggie. Even a 2 A PSU is underpowered for a 7 port USB hub. There should be, according to the USB 2.0 Standard, 500 mA on each port - so a minimum of 3.5 A would be required to be standards compliant. 2 A would only suffice for a 4 port hub.

Cheers.
Sure but in reality most people probably aren't going to have 7 devices that draw 500ma each :) The bigger issue is actually whether the PSU is a fire hazard or not, not whether it's got enough amps :)

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NormanDunbar
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Re: Don't but this USB hub

Wed Aug 29, 2012 6:14 am

Morning reggie,
reggie wrote:Sure but in reality most people probably aren't going to have 7 devices that draw 500ma each :) The bigger issue is actually whether the PSU is a fire hazard or not, not whether it's got enough amps :)
I agree, I don't have 7 USB devices myself, yet, and whether any or all will draw 500 mA is a moot point, but, to be compliant with USB 2.0 - which these devices claim to be - they must be able to supply 500 mA per port. If your power supply is only 2 A then your device is not compliant. And who knows what else is not compliant inside the hub?

Equally, if the hub does try to draw 500 mA per port and the PSU isn't man enough, will it fail safe, or simply burst into flames? Which is, I think, the point you are making about the PSU being a fire hazard.

I wonder how many people have USB hubs attached to computers that they leave on all the time, who are not aware of the potential fire hazard sitting there, innocently, next to their desktop?

Cheers.
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reggie
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Re: Don't but this USB hub

Wed Aug 29, 2012 11:15 am

Actually, no :) That's not my point about the fire hazard, my point is that your milage may vary on the quality of the psu, it could be that poor quality that just through normal useage it's unsafe, I wouldn't like to see the same quality soldering and missing components that are on one of the hubs, in the actual psu too!!

obcd
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Re: Don't but this USB hub

Wed Aug 29, 2012 12:03 pm

It's hard to say with chinese products. Most known name brands assemble in china as well.
So basically, everything can be properly assembled and sodered, or it can be homebrew soldered and terrible looking. The only way to know for sure is when you check it out yourself.
Our cable company sells digital setop boxes that consume 20W in standby and have a CE label. Nobody seems to care. It's a large company so they get away with it.
It's not that I am not willing to pay more for a known name good product.
The problem is they all make junk nowadays to furfill peoples needs.
And the last thing I want to do is pay more for a product, simply because it has an expensive name.
I love the days we had Luxman and Quad amplifiers that were pretty much undestructable.

reggie
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Re: Don't but this USB hub

Wed Aug 29, 2012 12:14 pm

obcd, agreed, there are lots of decent products coming out of china, that is undeniable, but these are cheap generic badge engineered hubs that are all over ebay, not ipads in the apple store :)

gritz
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Re: Don't but this USB hub

Wed Aug 29, 2012 1:42 pm

Lots of "lookey-likey" stuff crops up on ebay (and occasionally from reputable sellers who've been hoodwinked). Cloning of even not-very-posh hardware seems to be big business.

Some is so "lookey-likey" that one can only assume that it's the real thing spirited out of the factories' "fail" bins. I see this with electronic components - some are obviously fake, while others "look" perfect (regarding general appearance, silkscreen and whatnot), but just_don't_work to spec. (or at all).

Maybe that's how a factory shift manager makes his bonus. :lol:

obcd
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Re: Don't but this USB hub

Wed Aug 29, 2012 2:47 pm

One of the things they warn you about if you start manufacturing in china is that they likely will reverse engineer your product and sell the same thing under a different name. The hard engineering work is done, so they don't have any R&D costs that add to the price of the product.. The chinese clone of your product will have the same specs, as it's assembled on the same line by the same people. :D

This thread is about warning people for junk usb hubs and their supplies, so we are getting off topic.

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Jim JKla
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Re: Don't but this USB hub

Wed Aug 29, 2012 3:26 pm

obcd wrote:One of the things they warn you about if you start manufacturing in china is that they likely will reverse engineer your product and sell the same thing under a different name. The hard engineering work is done, so they don't have any R&D costs that add to the price of the product.
At a risk of staying off topic this only applies if a)there is a significant R&D component in the costs and b)the manufacturer can see a better market for the clone product.

The market may only prepared to buy the branded version.

As you say it's the junk products using either substandard parts or cheaper alternatives where the reverse engineering is not up to spec.

Sometimes they are the only game in town because the original is no longer available.
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If you find a solution please post it in the wiki the forum dies too quick

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