a-spence7
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Powered hub requirements

Tue Jul 10, 2012 10:57 am

Hi,

I'm looking to get a powered hub and was wondering if anyone had a similar setup and could recommend one.

Ideally I would like it to:
  • Power the PI (I understand that I can plug the USB into the powered hub and straight into the Y-USB power port??)
    Power a Wifi adapter (Edimax, EW-7811Un)
    Power a USB HDD (120GB 2.5", does actually run off 1 USB to Y-USB on my PC)
    Power a Wireless keyboard
Any ideas?

Thanks

a-spence7
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Re: Powered hub requirements

Fri Jul 13, 2012 9:21 am

Does anyone have any ideas? I don't want to end up buying something that doesn't work as I only need it for the RPi.

Hillpet
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Re: Powered hub requirements

Fri Jul 13, 2012 12:49 pm

I am using a Trust powered 7p hub (model 14524, 2 A):

feed the RPi from one of the powered ports
feed a 320 GB WD USB HDD from 2 ports (using a Y cable)
hook up a wired KB (cheap simple Trust)
hook up a wireless mouse

I still need to try out a wifi ethernet connection.

Works like a charm so far, hope it helps.

antiloquax
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Re: Powered hub requirements

Fri Jul 13, 2012 2:45 pm

I bought a Trust powered hub, but had problems.
This little kingston oneworks well though. I power the hub and then power the Pi from the hub. Works fine for a wifi-dongle and usb memory sticks. That's all I've tried so far (except kb / mouse ...)
mark

spongeburn
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Re: Powered hub requirements

Sun Apr 21, 2013 4:24 pm

Hillpet wrote:I am using a Trust powered 7p hub (model 14524, 2 A):

feed the RPi from one of the powered ports
feed a 320 GB WD USB HDD from 2 ports (using a Y cable)
hook up a wired KB (cheap simple Trust)
hook up a wireless mouse

I still need to try out a wifi ethernet connection.

Works like a charm so far, hope it helps.
Hi. I tried to use the Trust 14524 as well but my Pi is not recognising anything at all which is plugged in there. Did yours work out of the box or did you do any software/config adjustment? Thanks in advance for your feedback.

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MartP
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Re: Powered hub requirements

Fri May 03, 2013 4:18 pm

I don't like to "back-feed" my Pi(s) from a powered hub so I modded one of these
Image like this
Image
Image
to prevent back-feed of power to the host (the Pi)
The PSU supplied with this unit is another matter. I believe it advertises as a 2amp supply; mine states 1amp on the label, but I wouldn't bank on that :shock: Get a decent 3 - 4 amp 5v dc supply to power it, then it should be good to run peripherals to spec (500mA) on every port :) Although full loading of all ports may be pushing your luck :o

Martin

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rpdom
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Re: Powered hub requirements

Fri May 03, 2013 4:42 pm

MartP wrote:I don't like to "back-feed" my Pi(s) from a powered hub so I modded one of these
I got one of those hubs too. I also cut that track. However my hub seems very unreliable, even on my PC. Also, the PSU that came with it states (as you said) 1000mA, but can't even manage 5V on a model A with no peripherals attached. It dropped to 3.5V with a 30mA load!

I gave up on it in the end.

sdjf
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Re: Powered hub requirements

Fri May 03, 2013 4:54 pm

antiloquax wrote: This little kingston oneworks well though. I power the hub and then power the Pi from the hub. Works fine for a wifi-dongle and usb memory sticks. That's all I've tried so far (except kb / mouse ...)
mark
When I follow that link, it takes me to an Acco/Kensington Hub. What Hub is working for you, how about the model number rather than just a link?
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MartP
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Re: Powered hub requirements

Fri May 03, 2013 5:04 pm

rpdom wrote:
MartP wrote:I don't like to "back-feed" my Pi(s) from a powered hub so I modded one of these
I got one of those hubs too. I also cut that track. However my hub seems very unreliable, even on my PC. Also, the PSU that came with it states (as you said) 1000mA, but can't even manage 5V on a model A with no peripherals attached. It dropped to 3.5V with a 30mA load!

I gave up on it in the end.
Yes, I know what you mean, although the ones I have (I have two) seem reasonable - maybe it depends on the power supply used.
Martin

irishcanuck
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Re: Powered hub requirements

Fri May 03, 2013 6:01 pm

This powered usb-hub works fine: http://www.amazon.co.uk/Plugable-Speed- ... B2-HUB-AG7 . The rpi peripherals page (http://elinux.org/RPi_VerifiedPeripherals) says of same: "Plugable Port High Speed USB Hub USB2-HUB-AG7 USB 2.0 7-Port 5V - 3A ...Verified ...Better than usual power supply. There are US and UK power supply versions and it can be ordered in US and (for the UK version) many countries in Europe. There is a video showing this hub powering both the Raspberry Pi several peripherals at once. No back-voltage on upstream connection. Widely used with success on the Pi." Towards the end of the video it's mentioned "Plugable provides support for the linux kernal and drivers".
I can only assume back-voltage means back-feed from the Pi returning to the hub through the usb out, and this presumably this is undesirable...
Oh, but don't get this one, my Rasberry Pi didn't recognise it: http://www.amazon.co.uk/Imustbuy-Port-P ... ub+powered .
I use the following as a 5v 3A power supply: http://www.maplin.co.uk/3a-digital-car- ... tor-115314 . I've one to supply a regulated 12v to my eeepc and a second one as a real-time voltage meter to show the status of my (wind-turbine powered) battery.
Last edited by irishcanuck on Sat May 04, 2013 11:29 am, edited 5 times in total.

pjc123
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Re: Powered hub requirements

Fri May 03, 2013 11:26 pm

I am also using the Plugable USB2-HUB-AG7, 3 Amp, 7 port hub due to the positive wiki listing, good reviews various places, the fact that it has a specific port that will not backfeed the pi, and the demo on the plugable site showing it being used specifically with a raspberry pi. I only use it to power a wired keyboard, wired mouse, high gain wifi and the pi itself, but as you can see in the demo, it works with a lot of different devices.

Here is the hub:

http://plugable.com/products/USB2-HUB-AG7

Here is the demo:

http://plugable.com/2012/10/25/raspberr ... le-devices
My Raspberry Pi Project Page:
https://www.flaminghellmet.com/launch/

pjc123
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Re: Powered hub requirements

Sat May 04, 2013 11:16 am

irishcanuck wrote: No back-voltage on upstream connection. Widely used with success on the Pi.
What is back voltage anyway? Is it voltage from the Pi returning to the hub or something?
Back voltage or back feeding means that a hub is powering the pi from one of the hubs ports through one of the vertically stacked Type A ports of the pi, not through the pi's Micro-B power USB port. If this is done, the main polyfuse of the pi is being completely bypassed, so you either need to add some kind of external protection (fuse, circuit breaker, etc.) or you need to rely on any protection that the hub has, if it is even available at all and/or is the proper value. The USB2-HUB-AG7 has a special Mini-B port labeled "USB IN" that is used to connect to one of the vertically stacked Type A ports of the pi, and this connection will not back feed voltage into the pi. The pi is then powered properly by connecting one of the 7 Type A ports of the hub to the Micro-B power port of the pi.
My Raspberry Pi Project Page:
https://www.flaminghellmet.com/launch/

irishcanuck
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Re: Powered hub requirements

Sat May 04, 2013 11:53 am

I see. No back-feed means the pi gets it's supply as per normal with no other current slipping back to the pi from the usb devices connected to the pi. However back-feeding must be fairly common on many pi's connected to hubs without back-voltage protection on 'upstream connections' . What's the worst that can happen- a wonky usb device burns out a component or so?

re: the Plugable USB2-HUB-AG7-UK. It functions as a self-powered hub (ie. without the 3A 5v power supply connected) when there is adequate power available to the aforementioned 'USB IN' port (ie. from my netbook)
Last edited by irishcanuck on Sat May 04, 2013 12:11 pm, edited 2 times in total.

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rpdom
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Re: Powered hub requirements

Sat May 04, 2013 12:08 pm

irishcanuck wrote:What's the worst that can happen- a wonky usb device burns out a component or so?
With no protection from the fuse and protection diode, a USB hub with a bad PSU could fry the whole Pi. :(

irishcanuck
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Re: Powered hub requirements

Sat May 04, 2013 12:22 pm

That sounds nasty :(.

A raspberry pi then is at risk from a back-feeding power-loop; some hubs' 'power supply units' have been designed without protective built-in fuses and diodes (unlike the USB2-HUB-AG7), and therefore are unsuitable to users powering the main device (like the raspberrypi) via the hub *as well as* the requisite usb peripherals.
Last edited by irishcanuck on Sat May 04, 2013 2:42 pm, edited 2 times in total.

pjc123
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Re: Powered hub requirements

Sat May 04, 2013 12:35 pm

irishcanuck wrote:That sounds nasty :(.

So there's a potential risk from hubs with a bad 'power supply unit'.
No, every piece of electronic equipment works perfectly at all times, and there is never a danger of spilling coffee on it, connecting it wrong, a power surge, a lightning strike, a short in a cable between a device and the raspberry pi, etc. The polyfuse on the raspberry pi, such a silly thing. :roll:

As a side note, you are all replying to a post nearly a year old.
My Raspberry Pi Project Page:
https://www.flaminghellmet.com/launch/

irishcanuck
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Re: Powered hub requirements

Sat May 04, 2013 1:01 pm

Ha, ha,

sounds like the polyfuse is at the wrong end of the circuit-board!

Saw the post featured on the front page of the site yesterday. As I had just received my hub the day before I decided to sign up to the forum and undertake that daunting first thread
Last edited by irishcanuck on Sat May 04, 2013 1:03 pm, edited 1 time in total.

pjc123
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Re: Powered hub requirements

Sat May 04, 2013 1:02 pm

You really need to stop editing your post after someone replies:

You originally stated:
irishcanuck wrote:That sounds nasty :(.

So there's a potential risk from hubs with a bad 'power supply unit'.
And now it has been magically deleted.
My Raspberry Pi Project Page:
https://www.flaminghellmet.com/launch/

irishcanuck
Posts: 13
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Re: Powered hub requirements

Sat May 04, 2013 1:09 pm

Not magically deleted, edited. It's not saying the same thing? I told you, I'm new to this!
Last edited by irishcanuck on Sat May 04, 2013 1:21 pm, edited 1 time in total.

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rpdom
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Re: Powered hub requirements

Sat May 04, 2013 1:18 pm

irishcanuck wrote:Ha, ha,

sounds like the polyfuse is at the wrong end of the circuit-board!
Well, in the original releases of the Pi, there were polyfuses on the USB +5V outputs too. (F1 and F2) These were removed in later versions as they restricted the output to USB devices and prevented many from working.

irishcanuck
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Re: Powered hub requirements

Sat May 04, 2013 1:45 pm

That explains it, rpdom. All good aside from
spilling coffee on it, connecting it wrong, a power surge, a lightning strike, a short in a cable between a device and the raspberry pi, etc
:)

irishcanuck
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Re: Powered hub requirements

Sat May 04, 2013 5:29 pm

pjc123 wrote: The USB2-HUB-AG7 has a special Mini-B port labeled "USB IN" that is used to connect to one of the vertically stacked Type A ports of the pi, and this connection will not back feed voltage into the pi. The pi is then powered properly by connecting one of the 7 Type A ports of the hub to the Micro-B power port of the pi.
Judging from this, my above (edited as mentioned) comment regarding a 'back-feeding power-loop' is probably incorrect, making no difference whether the pi was powered from an unprotected hub or from a separate, isolated power supply.

sdjf
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Re: Powered hub requirements

Sun May 05, 2013 8:06 pm

I am totally confused by this discussion of backfeeding. How do I know that a hub will not send power back to the Pi via the host cable? I do not really need 7 ports and 3 Amps.

So much I have read says that hubs can power the pi, can can power without backfeeding, but that does not tell me if it also will not backfeed up the host cable.

I am powering my Pi with a motorola cellphone charger in the Power port, so do not need a hub to power it.

I just need a small hub that I can be sure will power speakers and a modem plus some memory devices. My 1 Amp Hub cannot handle both the speakers and the modem being plugged in at the same time, they seem to draw power even when not in use and make it impossible to read external memory devices without error.
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