Power Pi via a USB port?

Can a Raspberry Pi be powered via one of its USB data ports? Does it depend
on whether the Pi is the lower powered Model A or a Model B? No other USB
devices would be plugged directly in to the Pi but the onboard Ethernet
would be used.
I have ordered a powered USB hub with the intention of using it to connect
the Pi to a number of other devices. It hasn't arrived yet but I wondered if
it would at least be safe enough to try to power the Pi via one of its USB
ports. Anyone tried this?
James
Reply to
James Harris
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I don't thick you can power the Pi through the USB data connectors, but you can use an additional cable from the hub to power it. Problem is that probably the hub gives 500 mA max, and the PI needs more to work reliably.
Bye Jack
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Yoda of Borg am I! Assimilated shall you be! Futile resistance is, hmm?
Reply to
Jack
Yes, you can. Cheap USB hubs back-feed power to the source port (which they shouldn't), but it works.
However this does bypass the main fuse F3 (or F1 on recent boards), so you lose some protection.
You can also supply 5 volts to the GPIO connector on pins 2 or 4 and 6.
Reply to
Dom
Yes - On a Rev 1.1 or 2 Pi, not a Rev 1. (Either Model A or B, although note that the A doesn't have on-board Ethernet)
Yes. If the powered hub is "proper" and it doesn't back-feed power via the uplink cable/connection then you just need a normal USB to µUSB cable and power the Pi via the µUSB connector as normal.
Gordon
Reply to
Gordon Henderson
The Model B I use with RaspBMC is powered that way from a small powered hub:
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The flying lead is plugged into one of the Pi's USB data ports, the other Pi USB port has a wireless keyboard receiver in it. Power from a wall wart plugs into the hub via a small concentric power plug and for media storage there is USB powered HDD plugged into the hub. The Pi couldn't power the HDD directly.
The hub has a white LED that is literally blinding, a bit of black sticky tape cures that. It fits nicely on top of a Cyantech Berryblack case just above the ethernet port, held in place with a couple of tabs of self adhesive velcro.
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Cheers 
Dave.
Reply to
Dave Liquorice
yes, (but not the first revision, it yours has mounting holes it will work)
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umop apisdn
Reply to
Jasen Betts
I have powered mine from a USB hub and it has been working successfully for a couple of months as a weewx weather station server. It was not until I received my second Pi yesterday and wondered what the micro USB port was for that I realised that maybe I shouldn't be doing it!
Is it a bad practice?
Reply to
Gordon Levi
Type B II (with mounting holes) was built to do it that way.
Type B I didn't work properly because of the USB current limiting fuses. Solder a wire from USB+5V to +5V voltage check pin to overcome this.
But: it circumvents the current limiting line-in fuse. Stable powe is a must.
I've been doing it that way for ages.
--
Chris Elvidge 
England
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Reply to
Chris Elvidge

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