anthill
Posts: 5
Joined: Sun Mar 11, 2012 2:22 pm

Re: RasbPi powered by the USB port on a TV

Sat Mar 24, 2012 7:10 pm

Hello, well I guess this is fairly self explanatory.

Will the USB ports found on a lot of HD TV's power the Pi?

There must be a fair amount of current pulled through them as they power external HD's plugged into them when using the media player features!

Any idea's?

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5317
Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: RasbPi powered by the USB port on a TV

Sat Mar 24, 2012 7:42 pm

Works for me.

HansH
Posts: 212
Joined: Mon Sep 05, 2011 7:49 am

Re: RasbPi powered by the USB port on a TV

Sat Mar 24, 2012 10:46 pm

Yep, saves you an adapter.

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Jessie
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Location: C/S CO USA

Re: RasbPi powered by the USB port on a TV

Sun Mar 25, 2012 5:28 pm

In a majority of cases this should be no issue.  The 500mA minimum that is avalible from the TV USB ports should boot it just fine.  I say should because 500mA is the min and that is enough to power the R-Pi and a couple accesories.  Try to spin up a small hard drive plus the R-Pi on that port and unless the TV maker made a good amount of power avalible on that port you will run into issue.  But, a KB/Mouse, wifi, SD card, and USB stick plus the Pi should not be an issue.

anthill
Posts: 5
Joined: Sun Mar 11, 2012 2:22 pm

Re: RasbPi powered by the USB port on a TV

Mon Apr 09, 2012 7:57 pm

Thanks for the replies, I can't wait to get my hands on the Pi and start playing!

rustyk123
Posts: 4
Joined: Tue Apr 10, 2012 7:13 pm

Re: RasbPi powered by the USB port on a TV

Tue Apr 10, 2012 8:39 pm

Check your TV first before assuming, some provide power only on startup, some only in Firmware upgrade mode, and some all the time.  Just plug a mobile external hard drive (2.5", with no external power supply) in and listen for it to spin up, and keep spinning for a minute or so.  If the ports power is low, it would either click, spin then go off, or do nothing.  If it provides no power it will not do anything.

If yours provides low or no power, just go on eBay or some other website and buy a cheap usb power adapter, the very cheap iPhone adapters (like $3 should work perfectly, they don't work on iPhone, but perfect for anything else).  You may also be able to use something like the older Motorola adapters the use mini USB connectors, that way the cord is included and built-in.

n31l
Posts: 21
Joined: Fri Apr 06, 2012 8:27 pm

Re: RasbPi powered by the USB port on a TV

Tue Apr 10, 2012 9:36 pm

If the port is USB compliant then it would not work. But so many USB ports aren’t so it would. A USB port should not provide more than 100mA unless the connected device negotiates for the full 500mA. We have pulled over 1.5A out of a few laptops that just connect the 5V to their internal power rail.

So far non-compliant is the norm in the laptops we’ve looked at.

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Jessie
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Location: C/S CO USA

Re: RasbPi powered by the USB port on a TV

Thu Apr 12, 2012 4:41 am

n31l said:


If the port is USB compliant then it would not work. But so many USB ports aren’t so it would. A USB port should not provide more than 100mA unless the connected device negotiates for the full 500mA. We have pulled over 1.5A out of a few laptops that just connect the 5V to their internal power rail.

So far non-compliant is the norm in the laptops we’ve looked at.



1.5A is becomming common.  Many products tout this as a feature that allows faster charging of portible devices.  On my PC the 1.5A ports are color'ed red.  They are still regulated ports and are working as intended.

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