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Sep172014

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Wednesday, September 17, 2014 at 9:00PM

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Raspberry Pi - Power up using POE (Power Over Ethernet)

Robert Savage

Overview

(click image to enlarge) While this is certainly far from the first article on how-to power your Raspberry Pi via POE (Power-Over-Ethernet), I thought I would go ahead and document my setup and the equipment I ordered to pull this off successfully.

First, lets be clear -- I am using a real POE switch -- so I wanted a real POE solution for the Raspberry Pi, not one of those splitter cable solutions that simply supply a fixed power voltage over the unused pairs in a CAT5/6 ethernet cable. There is nothing wrong with that type of solution ... its pretty cost effective, but its not real POE per the IEEE 802.3af (POE) or IEEE 802.3at (POE+) specifications.

So to pull this off, we need a POE splitter that can provide the required 5 VDC voltage and an adapter micro USB cable to plug into the Raspberry Pi's power port. (And a short ethernet cable which you may already have laying around the house.)

Shopping List

The following items are included in this article:

Raspberry Pi POE to Micro USB 1m Heavy Duty DC Power Cable (LONG) ($7.80 USB + S&H)
~ or ~
Raspberry Pi POE to Micro USB 8" (20cm) Heavy Duty DC Power Cable (SHORT) ($6.80 USB + S&H)
1 ft CAT5/6 Ethernet Patch Cable (Varies)

TRENDnet Gigabit Power over Ethernet (PoE) Splitter, TPE-114GS ($24.99 USD)
~ or ~
TP-LINK TL-POE10R Gigabit PoE Splitter Adapter (~ $13.74 USD)

POE Splitter

You need a POE splitter than can output 5 VDC. I chose the TRENDnet Gigabit Power over Ethernet (PoE) splitter as it has a nice little selector switch where you can select between 5, 7.5, 9, and 12 VDC. You don't really need the Gigabit capability for the Raspberry Pi since it only supports 10/100 Mbps and TRENDnet does make a 10/100 POE splitter model that costs a little less. I purchased the Gigabit model thinking about other future projects I have in mind and wanted the additional speed.

I also (later) purchased the TP-LINK TL-POE10R Gigabit PoE Splitter Adapter adapter which was less expensive and as a bonus included a short CAT-5 ethernet cable. On the down-side it doesn't have the discrete LEDs specifically identifying which output voltage is selected, but that is a minor trade-off for the reduced cost.

Micro USB Adapter Cable

Since the POE splitter uses a barrel connector and the Raspberry Pi is powered using a micro USB connector, you will need an adapter cable to connect the POE splitter to your Raspberry Pi. At first I was going to make my own cable from spare cables lying around the house, but then I found this pre-made adapter cable on Amazon that fits perfectly. (Why reinvent the wheel .. Right?)

It's available in a short and long lengths:

Raspberry Pi POE to Micro USB 1m Heavy Duty DC Power Cable (LONG) ($7.80 USB + S&H)
~ or ~
Raspberry Pi POE to Micro USB 8" (20cm) Heavy Duty DC Power Cable (SHORT) ($6.80 USB + S&H)

Note: If you would like to purchase multiple quantities of this adapter cable you can order direct from Sean Kelley at Innovative Electronic Solutions and save on combined shipping.
http://www.innovativeelectronicsolutions.com/

Installation Steps

First, before attaching anything to the Raspberry Pi, make sure that the voltage selector on the POE splitter is set to 5 VDC. (You don't want to accidentally fry your Raspberry Pi!)
Connect your POE powered Ethernet cable from your network switch (or from your POE injector if you are using an injector) to the Data Power In port. Two green LEDs should be illuminated, the POWER LED and the 5V LED.
Connect the Micro USB adapter cable into the Power Out port and into the micro USB port on your Raspberry Pi.
Connect the short Ethernet patch cable between the Data Out port on the splitter and into the Ethernet jack on your Raspberry Pi.

Select 5 VDC