polymath
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Evolution of pi

Sun Jun 10, 2012 6:31 pm

I can see many possible applications for the Raspberry Pi in monitoring and control. Any ideas about what would be involved in making the Pi POE (power the Pi over the network). It would be too cool from my perspective.

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mxcum167
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Re: Evolution of pi

Sun Jun 10, 2012 7:09 pm

You need a POE splitter.

http://www.google.co.uk/products/catalo ... KkBEPMCMAA

Assuming you have a POE switch.

If not you will also need a POE Injector.

http://www.google.co.uk/products/catalo ... KoBEPICMAA
Martin www.chez-cummings.com

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Jim Manley
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Re: Evolution of pi

Sun Jun 10, 2012 10:12 pm

The Pi Ethernet connector is not configured for POE, nor is it supported in the firmware or kernel, AIUI.
The best things in life aren't things ... but, a Pi comes pretty darned close! :D
"Education is not the filling of a pail, but the lighting of a fire." -- W.B. Yeats
In theory, theory & practice are the same - in practice, they aren't!!!

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mxcum167
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Re: Evolution of pi

Mon Jun 11, 2012 3:10 pm

Jim Manley wrote:The Pi Ethernet connector is not configured for POE, nor is it supported in the firmware or kernel, AIUI.
Correct, but a POE splitter would allow you to power the Pi from a POE switch, as it takes the power presented by POE and delivers it separately.
Martin www.chez-cummings.com

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Jim Manley
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Re: Evolution of pi

Mon Jun 11, 2012 4:18 pm

mxcum167 wrote:
Jim Manley wrote:The Pi Ethernet connector is not configured for POE, nor is it supported in the firmware or kernel, AIUI.
Correct, but a POE splitter would allow you to power the Pi from a POE switch, as it takes the power presented by POE and delivers it separately.
If the power is split out via a pigtail with a micro-USB male plug that's connected to the Pi's power socket, that should work, but, only if there is enough current capacity (at least a solid 1+ amps at no less than 4.9 volts, and that's with a minimal keyboard and mouse if a powered USB hub isn't used). The board could not be powered via the Ethernet connector on the Pi, as power would not be passed through on the printed-circuit board from what the Foundation folks have said. The Pi could not be connected the way something like a network-powered phone normally would be, which is what I wanted to emphasize.

I suppose there might be educational situations where POE would be available, but, this isn't going to be typical, and very unlikely in any residential environment - it would be nice, though. It's not that big a deal, however, as with the low power requirements of the Pi, it's just a matter of time before some kind of environment-derived power sources are developed from pedaling, thermal differential conversion (e.g., bimetallic transfer), ambient (non-solar) light or infrared conversion, garbage compost heat/gas, puppy power, etc. (no puppies, children, etc., were harmed in the writing of this comment ;) ).
The best things in life aren't things ... but, a Pi comes pretty darned close! :D
"Education is not the filling of a pail, but the lighting of a fire." -- W.B. Yeats
In theory, theory & practice are the same - in practice, they aren't!!!

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AndrewS
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Re: Evolution of pi

Mon Jun 11, 2012 5:03 pm

I can see that POE (via a POE splitter) would also be useful in "remote sensor" type applications - only one cable to run instead of two. Or even as IP cameras - ethernet cables can be much longer than USB cables.
https://en.wikipedia.org/wiki/Power_over_Ethernet 12W is more than enough for a Pi and any peripherals, even allowing for any losses in the DC-DC conversion.

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