Powering with a Hub


7 posts
by hairydalek » Fri Jun 22, 2012 12:36 pm
My question is about USB. Right now, to power up (and down) the Pi, I need to pull the USB plug from the Pi and re-insert it. This has a finite life, and I’d rather not have to do this all the time. It feels fragile, and I’d rather have another way of cycling the power.

I am also pondering building a box for it, and this would need access to the ports, as well as providing power to the system. The best option I can think of is using a USB hub to power the Pi, and ALSO to provide a way to extend the USB capabilities of the Pi.

So, my question is: is it safe to do this? Basically, the USB hub would be connected to the mains. The data in cable would be connected to the Pi. One of the “out” ports would be connected to the Pi’s power in socket. See this diagram:
ImageClick for large view - Uploaded with Skitch

Is this kind of loop-back OK to do? I’d rather have one power lead (USB hub) than two (hub+Pi).

I’d then be able to use something like this:
http://www.amazon.co.uk/LUPO-Port-USB-2 ... 01&sr=1-93
to route USB ports and power to where I’d need it.
All the best,
Paul.
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by AndrewS » Fri Jun 22, 2012 12:50 pm
Yup, that's exactly what many people do already :)
The only caveat being that (according to the specs) USB ports can only supply 500mA, and the RPi needs up to 700mA, so you may need to get a "Y adaptor" to connect two of the USB hub's ports to the RPi's power input. Or you might have a "low quality" Hub which doesn't have any output-power-limiting, in which case you're sorted ;)
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by Iedjee » Fri Jun 22, 2012 3:19 pm
See my post:
http://www.raspberrypi.org/phpBB3/viewtopic.php?p=73120#p73120

I got the Emiment EM1126 hub for around 15 euros (Netherlands).

As soon as i get my ModMyPi-case i will stick both cases together and post a picture of it.

Greetz, EJ
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by SN » Fri Jun 22, 2012 3:25 pm
This is what I use, just over £6 - I have two and they do the job nicely, exactly as in your diagram
http://www.ebay.co.uk/itm/280522733324
Image
Oh and you can very easily strip them down to bare pcb to match you pi if you wish... :lol:
Steve N – binatone mk4->intellivision->zx81->spectrum->cbm64->cpc6128->520stfm->pc->raspi ?
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by mikerr » Sat Jun 23, 2012 12:53 pm
I use this one which has a handy power switch already on it:

Image
http://www.ebuyer.com/259356-xenta-black-4-port-usb-2-0-hub-with-on-off-switch-n-uh105

The power switches off all the usb ports - handy for resetting.
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by mark gawler » Sun Jun 24, 2012 12:02 pm
mikerr wrote:I use this one which has a handy power switch already on it:

Image
http://www.ebuyer.com/259356-xenta-black-4-port-usb-2-0-hub-with-on-off-switch-n-uh105

The power switches off all the usb ports - handy for resetting.

This is an unpowered USB Hub, people a talking about powering the Pi from the Hub.
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by reggie » Mon Jun 25, 2012 3:27 am
those 7 port hubs are a bit junky, missing caps, no seperation between vUsb and 5v in, roulette as to whether you're going to get a good or bad power supply.
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