Power Over Ethernet Splitter Improves Negotiating Skills

Implementing PoE is made interesting by the fact that not every Ethernet device wants power; if you start dumping power onto any device that’s connected, you’re going to break things. The IEEE 802.3af standard states that the device which can source power should detect the presence of the device receiving power, before negotiating the power level. Only once this process is complete can the power sourcing device give its full supply. Of course, this requires the burden of smarts, meaning that there are many cheap devices available which simply send power regardless of what’s plugged in (passive PoE).

[Jason Gin] has taken an old, cheap passive PoE splitter and upgraded it to be 802.3af compatible (an active device). The splitter was designed to be paired with a passive injector and therefore did not work with Jason’s active 802.3at infrastructure.

The brain of the upgrade is a TI TPS2378 Powered Device controller, which does the power negotiation. It sits on one of two new boards, with a rudimentary heatsink provided by some solar cell tab wire. The second board comprises the power interface, and consists of dual Schottky bridges as well a 58-volt TVS diode to deal with any voltage spikes due to cable inductance. The Ethernet transformer shown in the diagram above was salvaged from a dead Macbook and, after some enamel scraping and fiddly soldering, it was fit for purpose. For a deeper dive on Ethernet transformers and their hacked capabilities, [Jenny List] wrote a piece specifically focusing on Raspberry Pi hardware.

[Jason]’s modifications were able to fit in the original box, and the device successfully integrated with his 802.3at setup. We love [Jason]’s work and have previously written about his eMMC adventures, repairing windows tablets and explaining the intricacies of SD card interfacing.

Wiring The ESP-32 To Ethernet

Since its introduction years ago, the ESP-8266 has taken over the world. It’s the chip inside thousands of different projects, and the basis for dozens of different IoT thingamadoos. The follow-up to the 8266, the ESP-32, is even more capable. It has a ton of peripherals inside, including an Ethernet MAC. What’s that? Yes, it’s possible to put Ethernet on an ESP-32, and give an IoT board PoE. That’s what [Patrick] is doing for his Hackaday Prize project, and it’s an awesome idea.

This build began as you would expect, with an ESP-32 module attached to one side of a board with some breakouts for the GPIOs and a USB to Serial chip. The tricky part here is the PoE part of the Ethernet, which requires MagJack Ethernet connectors, a flyback transformer, and a PoE-PD controller. These were expensive parts, and the design of such a board requires some thinking — you need isolation across the transformer, and proper ground planes for this mess.

There’s something slightly brilliant about using an ESP-32 in a wired configuration. Far too often, we see these modules used as wireless nodes in a sensor net. The battery consumption is significant, and all those makers are adding USB power input to their fancy WiFi sensor nets. If you’re running wires for power anyway, why not add Ethernet and do away with all that mucking around with WiFi setup. It’s a great project, and one of the better entries in this year’s Hackaday Prize.

Hacklet 94 – Pi Zero Contest Entries

Hackaday and Adafruit have joined forces to present the Raspberry Pi Zero Contest. A great contest is nothing without entries though. This is where the Hackaday.io community is proving once again that they’re the best in the world. The contest is less than a week old, yet as of this Thursday evening, we’re already up to 33 entrants! You should submit your own project ideas now for a chance at one of the many prizes. This week on The Hacklet, we’re going to take a look at a few of these early entrants!

controllerWe start with [usedbytes] and Zero Entertainment System [usedbytes] has crammed an entire emulator into a classic Nintendo Entertainment System control pad thanks to the Raspberry Pi Zero. Zero Entertainment System also has something the original NES couldn’t dream of having: An HDMI output. The emulator uses the popular RetroPie front end. We’re happy to say that [usedbytes] knew that hacking up a real Nintendo controller would be sacrilegious, so they grabbed a low-cost USB clone from the far East. A bit of creative parts-stuffing and point-to-point wiring later, ZES was ready to meet the world!

wsprNext up is [Jenny List] with The Australia Project. [Jenny] is a hacker from Europe. She’s hoping to use a Pi Zero to talk to Australia. “Talk” may be pushing it a bit though. The Australia Project will use the Weak Signal Propagation Reporter (WSPR) network to transmit RF straight out of the Pi’s GPIO ports. All that is required is a good filter, an antenna, and a balun. The filter in this case is a 7-pole Chebyshev low-pass filter. The filter keeps the Pi’s harmonic filled square waves from messing up every band from DC to light. [Jenny] normally sells these filters as a kit, but she’s made a special version specifically for the Pi Zero.

tote0[Radomir Dopieralski] has brought his signature walking robots to the Pi Zero world with Tote Zero. Tote Zero is a quadruped walking robot built mainly from 9 gram servos. [Radomir’s] custom tote board interfaces the servos to the Pi Zero itself. The Pi Zero opens all sorts of doors for sensors, vision, and advanced processing. The Arduino board on the original Tote would have been hard pressed to pull that off. Tote is programmed in Python, which will make the code quick and easy to develop. Tote Zero just took its first steps a few days ago, so follow along as a new robot is born!


ethernetpoFinally we have [julien] with PoEPi: Pi Zero Power over Ethernet with PHY. The Raspberry Pi Zero is so tiny, that it’s easy to forget it needs a fair amount of power to run. [Julien] is giving us a way to connect our Pi to a network while ditching the USB power supply using Power Over Ethernet (PoE). PoE has been powering devices like IP cameras for years now. It’s become a standard way of transmitting power and data. For the Ethernet physical interface, [Julien] is using Microchip’s ENC28J60, which has a handy SPI interface. Linux already has drivers in place for the device, so it’s a slam dunk. The “power” part of this system comes with the help of an LTC4267 PoE interface chip, which has a built-in switching regulator.

If you want to see more entrants to Hackaday and Adafruit’s Pi Zero contest, check out the submissions list! If you don’t see your project on that list, you don’t even have to contact me, just submit it to the Pi Zero Contest! That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

DIY Solution Does PoE On The Cheap


Depending on the scope of your requirements, Power over Ethernet (PoE) components can get pretty pricey. [Fire] wrote in to share a 4-port PoE solution he put together for under 20 euros (Ignore any SSL errors – we’ve checked it out, it’s safe).

The most expensive part of the build was the 8-port patch panel he purchased for 11 euros. He popped it open, wiring the first four ports for power after drilling spots for an indicator LED and the PSU. He wound the power lines through ferrite beads to hoping to dampen any interference that might occur before reassembling the panel.

In the picture above, you might notice that the panel is being powered via the first Ethernet port rather than through the barrel jack, which [Fire] said was done for testing purposes. When deployed in his network, he plans on using a regulated power supply from a junked laptop to provide electricity.

If you need to provide PoE to devices on your network, this is a great way to go about it. Using a patch panel like [Fire] has gives you the flexibility to easily wire up as many powered ports as you need without much hassle.

POE Home Automation Control Panel


[Scott] wrote in to share a project he is currently working on, a home automation system that relies on Power over Ethernet. While he’s not completely finished, he’s made some great progress, and the work he has done so far definitely piqued our interest.

Part of [Scott’s] design relies on some reverse engineered Blackberry screens we showed you a while back. He has constructed a small control panel for his apartment, which incorporates one of the aforementioned Blackberry screens, along with 10 tactile switches and a PIR sensor. The panel is built to be mounted in a wall or as a standalone unit, allowing him to control various lights and appliances throughout his home.

[Scott] spent a lot of time working on the communications protocol and UI for his control panel. As it sits now, the panel takes advantage of a VNC-like protocol he designed, which allows him to interact with a Java application residing on his desktop computer.

Things are looking awesome so far, and [Scott] already has a handful of improvements planned for the near future. We can’t wait to check it out when it’s finished.

Powering A Switch Via PoE

[Kajer] was doing some work with IP phones that use Power over Ethernet. While trying to get this to work with a network switch he decided to use PoE to power the switch itself. The best thing about this is he managed to shoehorn all of the necessary bits into the stock case. Those bits include a bridge rectifier, transistor, resistor, and a 5v power supply. Along the way he discovered he can now power the switch off of USB if he wishes.

Glowing Patch Cables

[Sleepydog] just sent in this cool video of a patch cable he made with a built in EL wire. He’s using a Power over Ethernet router to control which ports have power. He states that this would allow easy identification of specific cables in the mess. While the proof of concept seems completely functional, and the idea is nice, we have to wonder if the cost to put in all the extra hardware would be worth it. Each cable would have to have its own inverter, not only driving up cost, but possibly adding interference. That does not mean we don’t want this desperately, we do. But we want it just because it looks cool. He needs to choreograph this to some music now and make his entire server room into a fancy display.