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Is it possible to modify the Pi, so that it can receive it's power via Power over Ethernet (PoE)?

I would like to be able to power my unit via the ethernet cable, so that I don't have to worry about running power cords around the place.

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Possible duplicate: Powering without using the micro USB –  Flexo Jun 26 '12 at 11:58
    
but you still need to run network cords? –  Thorbjørn Ravn Andersen Aug 12 '12 at 22:42
    
@ThorbjørnRavnAndersen that's OK they're well insulated and can handle the outdoors a lot better than a flimsy DC cable. –  darryn.ten Aug 13 '12 at 7:06
    
HI Recently used one of these. It solves the problem and works well. –  user6983 Apr 17 '13 at 16:32
    
www.youtube.com/watch?v=jmfkwmsMUs8 –  user6983 Apr 17 '13 at 16:32

5 Answers 5

up vote 20 down vote accepted

As previously discussed RPi does not support PoE. And yes you could use a PoE module to hookup power to GPIO. But if you're not up for hardware hacking you could just get a Ethernet/USB power splitter off the shelf.

For up-to-date product list Google is your friend. Searches to use include:

Sample products include:

  1. http://www.cjemicros.co.uk/micros/individual/newprodpages/prodinfo.php?prodcode=TPL-POE+ADAPT
  2. http://www.dabs.com/products/cisco-5-volt-power-over-ethernet-spl-771C.html?utm_source=google&utm_medium=product+search&utm_content=Q200
  3. http://www.noveltechnologies.co.uk/pgProduct.cfm?Product=16787_156_1343834-52769-560443-Intellinet_Network_Solutions_560443_PoE_Splitter_5_V_DC_7_5_V_DC_9_V_DC_12_V_DC_Output_Black

N.B: All except the first will need 2.1mm to USB adapter as well.

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I know that we don't usually post links to products, but they are kinda hard to find. And may be worth around keeping until RPi accessories become common place. It's worth noting that the first one even lists RPi compatibility!! :) –  Maria Zverina Jun 26 '12 at 13:44
    
    
As the post says, most PoE adapters will require a 2.1mm-to-USB cable or adapter. These can be expensive and/or hard to obtain. As an alternative it's also possible to use a combination of cables (e.g. 2.1mm-to-USB-A plus USB-A to micro-USB) that may be cheaper/easier to come by - more details here. –  psmears Aug 12 '12 at 17:20

Yes, it would be possible. You would need to modify the board with a PoE module:

PoE Module

Which you could hook up to the main power lines, or to the power line on the GPIO, which can be examined in this question.

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@Itehnological How is that relevant? As explained, that's at 48V. –  Alex Chamberlain Aug 12 '12 at 19:20

If you want a Raspberry Pi PoE solution that conforms to IEEE 802.3af Standard (PoE), then try the Xtronix Raspberry Pi interface. It is not cheap, but it allows the Pi to be powered via the ethernet cable from a standard PoE hub/switch. The IEEE 802.3af PoE standard defines how devices can be powered over the CAT 5 Ethernet cable.One of the issues the standard addresses is that of safety. A hub/switch that meets the standard allows Poe and non-Poe devices to be mixed safely in the network.

You can buy these via eBay.

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thanks for the link! is there any way to get a case for this vehicle ;) ? –  Alex Tape Feb 5 at 9:01

There is an PoE-Modul for the Arduino named "Ag9120-S":

With this, you have to modify the Wiring at the Network-Connector

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I will answer with the assumption that you want to have a solution that interfaces directly with the Raspberry Pi's ethernet connector.

First of all, the RPI uses a magjack, not merely an RJ-45 connector. The best I can tell from the B board, they use an EDAC A63-113-300P131 magjack.

The manufacturer's schematic is below, followed by the connector symbol from RPI-B schematic, and the pinout. They agree, although the manufacturer and RPI folks number the pins differently.

EDAC magjack schematic magjack schematic from RPI-BEDAC magjack pinout, top-view

A compliant PoE solution needs access both to the primary winding center taps, and to RJ45 pins 4, 5, 7 and 8. Those are (of course!) not available outside the magjack in use.

One hacky solution is to desolder the magjack, remove the 75 Ohm resistors, and bring out the center taps and the pins 4,5,7 and 8. There's at least one person who did just that, and wired it to the PEM1205 PoE module.

A less hacky solution would be to find a PoE magjack with the same mechanical outline and pinout, and solder it in place of the original magjack. PoE magjacks can have built-in rectifiers, requiring only 2 pins to pass the power to the PoE supply - thus requiring only 8 pins total (6 for data, 2 for power). Such 8 pin magjacks do in fact exist.

Unfortunately, all the magjacks that DigiKey currently stocks - those by Bel Fuse, TRP, Wurth and Pulse, have wrong pinouts. Some would mechanically fit, perhaps with a pin or two cut, but the pinout is all wrong.

The only solutions I can think of, that would still retain the small form-factor of RPI, and its 3D bounding box, would be to unsolder the original magjack and:

  1. Add a small interposer board between a different magjack and the RPI. The board would sit directly between the magjack and the RPI, moving the magjack about 0.07 inches higher. It would expose the 5 pins needed for PoE operation (shield, center taps, 4+5, 7+8), or the 3 pins if a rectifier magjack is used. Cons:

    • The RPI's case needs to be modified to accommodate the elevated magjack.

    • The connector's pins have to be trimmed before being soldered into the interposer board, since the board must sit flush with the RPI board.

    • If the PoE board is to be soldered directly into the interposer, the interposer will hang outside of the RPI's outline.

  2. Add an adapter board with tall pins that go behind the new magjack, with the magjack soldered upside down and moved out. Pros:

    • The cases don't need to be modded - the magjack will fit through existing case hole.

    • The adapter board can accommodate the PoE board itself.

    Cons:

    • The magjack will stick out by ~0.2 inches. The extra space behind it is needed for the pins that go between the RPI's magjack signal pads and the adapter board.

    • The 0.5 inch long interposer pins are inserted into the ethernet data pairs. This presents an impedance mismatch and may not make the solution 802.3 spec compliant.

The PoE boards are available in multiple output voltages. You can use a 5V board and feed its output directly into P1 connector's pins 2 and 4. If you push more than 5V into those pins, you'll destroy the PI, so be careful if you wish to implement one of the suggestions.

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