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Is it possible to power the device without using the micro USB? For example, is it possible to use PoE (Power over Ethernet)?

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I guess you could solder wires onto the board :) – Martin Thompson Jun 13 '12 at 20:10

4 Answers

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Yes it is possible.

But not with PoE. The board can be powered using the GPIO. Here is a pin diagram showing the pins for power at the top.

enter image description here

Maximum permitted current draw from the 3v3 pin is 50mA.

Maximum permitted current draw from the 5v pin is the USB input current (usually 1A) minus any current draw from the rest of the board.

Model A: 1000mA - 500mA -> max power draw: 500mA

Model B: 1000mA - 700mA -> max power draw: 300mA

You can read more on elinux.

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Would connecting 5v and GND to the GPIO be enough or is the 3.3v needed too. Wouldn't adding/extending the 5v and GND on the RPi power USB port and connecting a 5v wall-wart or the 5v line from a computer power supply. – Hellonearthis Aug 14 '12 at 14:01
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The Ethernet port does not support PoE. Therefore, you cannot use PoE without external hardware; it would be necessary to convert the 48V down to 5V. It should limit the current to 1A.

Untested (Possibly) Useful Hardware

See also: What do I need to know when choosing a dedicated power supply?

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Maybe include an example of what kind of external hardware someone would need? – Bryan Dunsmore♦ Jun 13 '12 at 19:44
Slightly better? – Alex Chamberlain Jun 13 '12 at 19:54
Wonderful. Upvote for you! =D – Bryan Dunsmore♦ Jun 13 '12 at 19:55
   
Presumably this method would still provide the power through the micro-USB port though, so I guess the answer to the question is "No, except for soldering wires onto the board"? – Highly Irregular Jun 19 '12 at 1:11
I suppose I have answered "Can I power the Raspberry Pi using PoE?". – Alex Chamberlain Jun 19 '12 at 6:03
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up vote 2 down vote

It doesn't support IEEE 802.3af standard PoE. But PoE is the CONCEPT of running the voltage over the unused (or overvolting the USED) DC wires on the Cat5 cable. (Blue and brown/blue+white and brown+white). And the Raspberry Pi CAN be modified to do this...

I imagine it can be wired over Cat5/Cat6. But need to make sure after the DC is taken to power the Pi that you're not overvolting the RJ45.

(3.3v actually I think for Raspberry) - and for PoE, you can use blue wires or brown depending on your design. (IEEE 802.3af is DC+ on pins 4,5 and DC- on 7,8). If you didn't know you can connect a Cat5 cable, strip it. Cut the blue and brown wires, and it will still work. You can use this princple to wire the DC over those wires, and take it off before it enters the 8p8c modular plug, or before it hits the pcb after the plug.

I'd build my own injector too btw.

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If you want a Raspberry Pi PoE solution that conforms to IEEE 802.3af Standard (PoE), then try the Xtronix Raspberry Pi interface - xtronix.co.uk/raspberry-pi-poe.htm. 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. Hope this is of help - Regards Jim

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