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narsaw
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Power from rev2 USB Port

Fri Dec 07, 2012 10:26 pm

I've got a rev2.0 RasPi and was wondering what voltage and current does the RasPi output via it's two USB ports?

Note: I am not asking about powering the RasPi via USB, I want to know how much power (V and A) does the RasPi outout via it's 2 USB ports.

Basically I want to use a "bus powered" USB 1TB drive via the RasPi. The 1TB drive does not have a port for power just a single USB cable.

Image

poing
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Re: Power from rev2 USB Port

Fri Dec 07, 2012 10:33 pm

About 150 mA for both ports I think. You'll definitely need a powered USB hub to use that drive.

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narsaw
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Re: Power from rev2 USB Port

Fri Dec 07, 2012 10:36 pm

Just checked, this drive requires 500mA of power to operate.

Can someone confirm the 150mA for the Rev 2.0, Model B?

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Dweeber
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Re: Power from rev2 USB Port

Fri Dec 07, 2012 10:48 pm

Poing has it right. You will need to use a Powered USB Hub.
Dweeber A.K.A. Kevin...
My RPI Info Pages including Current Setup - http://rpi.tnet.com

poing
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Re: Power from rev2 USB Port

Fri Dec 07, 2012 11:01 pm

narsaw wrote:Can someone confirm the 150mA for the Rev 2.0, Model B?
What you can do with a V2 board is put power on one of the two USB-A ports and put your drive in the other. That way the power to the drive doesn't go 'through' the Pi. A V2 Pi can be powered from the USB-A ports. The downside is that you need to rig up your own cable or find a USB-A to USB-A cable to put between the power supply and one of the Pies' USB-A ports.

Dilligaf
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Re: Power from rev2 USB Port

Fri Dec 07, 2012 11:33 pm

Actually the power output to the usb ports on a V2 board is only limited by the input fuse and the power supply so with a good enough power supply the drive will probably work. If you power the PI from the gpio bypassing the input fuse you could probably power multiple drives from the usb ports it was discussed in another thread and if I remember correctly the traces on the circuit board should handle about 2 amps

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narsaw
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Re: Power from rev2 USB Port

Fri Dec 07, 2012 11:37 pm

Dilligaf wrote:Actually the power output to the usb ports on a V2 board is only limited by the input fuse and the power supply so with a good enough power supply the drive will probably work. If you power the PI from the gpio bypassing the input fuse you could probably power multiple drives from the usb ports it was discussed in another thread and if I remember correctly the traces on the circuit board should handle about 2 amps
Now this sounds interesting. If we could somehow by-pass this fuse it would be great.

Has anyone done this, please post links.

I am guessing this would void warranty but that's ok too.

itimpi
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Re: Power from rev2 USB Port

Fri Dec 07, 2012 11:39 pm

A much easier (and safer) solution is to get a powered hub (2A+) and use it to power both the Pi and the HD.

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