bodgefinder
Posts: 2
Joined: Wed Oct 09, 2013 12:11 pm

Using a Powered USB Hub

Wed Oct 09, 2013 12:52 pm

I have the R-PI model B and a Powered USB Hub. If I connect the USB Hub to one of the R-PI's USB ports, and power the USB Hub up before the R-PI, won't the USB Hub's internal power rail then "back power" the R-PI via the +5V supply signal back up the USB cable into the R-PI and so effectively powering up the R-PI but bypassing the poly-fuse. :?:

texy
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Forum Moderator
Posts: 5160
Joined: Sat Mar 03, 2012 10:59 am
Location: Berkshire, England

Re: Using a Powered USB Hub

Wed Oct 09, 2013 1:27 pm

Hi and welcome to the forum,
yes - so choose a hub that doesn't connect +5v to the host port, or cut the connection yourself (if it concerns you).

Texy
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):
https://www.raspberrypi.org/forums/viewtopic.php?f=93&t=147682#p971555

lenkf
Posts: 19
Joined: Wed Jul 10, 2013 10:02 pm
Location: S.California

Re: Using a Powered USB Hub

Wed Oct 09, 2013 10:01 pm

NO. Well, at least mine doesn't. I have a common DLink DUB-H7 7 port, 3 amp powered hub. When I disconnect power from the micro usb power connector to the rpi, the rpi's LEDs turn off! If the rpi is powered down, and the usb hub is powered down and the rpi plugged into the hub, if I turn on the hub, the rpi does not get power. I have to apply power to the rpi's separate power supply before the rpi does anything :)

Maybe the previous poster has a different kind of powered master/slave usb hub than i am using.

Fred

bodgefinder
Posts: 2
Joined: Wed Oct 09, 2013 12:11 pm

Re: Using a Powered USB Hub

Fri Oct 11, 2013 9:06 am

The one I have is a Dynamode 7-Port Powered USB Hub, and it is the one supplied with the R-Pi kit from CPC (Farnell) but I am seeing a few posts on other forums warning users that this Hub does give problems, so I will start off by using the 2 ports on the R-Pi for KBD and Mouse only and go from there.

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