Crappy hub. Danger?


5 posts
by Gayspy » Wed Jul 04, 2012 11:14 am
Hi guys.

I have a USB hub that presumably can be powered by the host or with an external power source. When I connect the hub to an external power source with R-Pi connected as the host, the R-Pi powers on(no power cable attached to the pi). The hub is powering the pi through the R-Pis USB host port.

The hub is super simple. There are barely any components on the board. Just an LED.

Is this a bad thing? Will this damage my pi? If not, should I leave the micro-USB power cord disconnected(i was planning on powering the pi from that same hub). My pi hasn't blown up yet so it can't be super bad.

Hub is this here.

Sorry, available only in ridiculous languages.

Thanks
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by RaTTuS » Wed Jul 04, 2012 12:05 pm
http://www.catb.org/esr/faqs/smart-questions.html <- ask smart Questions
"That's not right, the badgers have moved the goalposts."
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by Gayspy » Wed Jul 04, 2012 12:23 pm
Thanks.

So cut the red wire from the usb cord that goes from R-Pis host port to the hub to stop Raspberry Pi from powering the hub at all.
Raspberry Pi cannot be powered reversely through USB host port due to the polyfuse.
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by RaTTuS » Fri Jul 06, 2012 2:19 pm
see viewtopic.php?f=46&t=5623&p=117252#p117252
you cannot * successfully* power the RPi from a back powered USB port
if you are powering the RPi from the same hub as you are using as a HUB but it should not matter and you should be able to get away with snipping the red wire on that rpi-> hub connector [or leave it be]
if you bypass the polyfuse like
viewtopic.php?f=63&t=8591&hilit=bypass#p102485
then you may be able to power it via the usb socket .... YMMV

edit
[got the links right now]
http://www.catb.org/esr/faqs/smart-questions.html <- ask smart Questions
"That's not right, the badgers have moved the goalposts."
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by Dilligaf » Sat Jul 07, 2012 3:39 am
If you plug the micro usb cable into one of the hubs outputs to the Pi power input and simply pull the plug on the hub to shut down then you should have no problems. Not necessary to cut anything.
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