Power Pi via a USB port?

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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



Re: Power Pi via a USB port?

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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
--  
Yoda of Borg am I! Assimilated shall you be! Futile resistance is, hmm?

Re: Power Pi via a USB port?
On 25/04/14 18:18, James Harris wrote:
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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.


Re: Power Pi via a USB port?
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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)

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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

Re: Power Pi via a USB port?
On Fri, 25 Apr 2014 18:18:08 +0100, James Harris wrote:

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The Model B I use with RaspBMC is powered that way from a small
powered hub:

http://m.cpc.co.uk/en-GB/product.aspx?c92%&p=9&pid=CS23309

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.

--  
Cheers
Dave.




Re: Power Pi via a USB port?
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yes, (but not the first revision, it yours has mounting holes it will work)

--  
umop apisdn


Re: Power Pi via a USB port?

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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?

Re: Power Pi via a USB port?
On 06/05/2014 14:18, Gordon Levi wrote:
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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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