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.
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:
N.B: All except the first will need 2.1mm to USB adapter as well.
Yes, it would be possible. You would need to modify the board with a
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.
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.
There is an PoE-Modul for the Arduino named "Ag9120-S":
With this, you have to modify the Wiring at the Network-Connector
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.
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:
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.