Omega PoE Dock



  • Hi All,

    I've put together a board design that (hopefully) powers an Omega over Power-over-Ethernet (IEEE 802.3af).
    This is the standard that powers many wireless access points and VoIP desk phones using 48 VDC over standard network cables, with up to 15 watts in the initial 802.3af version of the standard.

    My board is the smallest thing I could make has electrical isolation from the PoE supply, while supplying 12V@1A, 5V@2A, and 3.3V@2A. Of course, it also connects the Ethernet communications to the Omega, and has an expansion header, as well as 12V and 48V power headers. I specifically designed it for 12V to support powering external hardware, such as 12V LED lighting strips.

    The design files are up on Github, and I've just ordered parts for the whole thing. At this point, it's an untested design, so I'll have to wait several weeks to get one in my hands to see if it works.

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    If anyone is interested in something like this, let me know, and I'll keep you posted about how it goes. There's a non-zero possibility of a group buy if this design works.



  • @Scott-G Are you going to make any available for sale? Say Tindie?



  • Hi Scott,

    That is an awesome project. I use a lot of Ubiquity gear, and they have a non standard 24V PoE. Would the circuitry still work with 24V instead of 48V?

    Bas



  • I would be interested in this if it supported 24V PoE. Really interesting!
    Are the schematics available? I’ll take a further look at what you’ve provided when I get a chance.



  • Are you passing through the Ethernet PHY from the Onion itself, or is this actually a second Ethernet interface itself as well?



  • @Earl-Baugh I don't want to them not be for sale, but that doesn't mean that I necessarily want to be the one to sell them.

    My big driver is that they're darned expensive to get manufactured in small quantities (like $100 for 1, $85 for 2), but they're affordable if you make several hundred (~$30). I want to be able to buy several for my own use, and I want to hardware design to be open, so I'd be delighted if there were a group buy that made it cheaper for me.

    The catch is that, well, I already have a job. I don't really want a second job. Manufacturing these and selling them sounds like a second job. An ideal situation for me would be if some company wanted to take care of all of the annoying business details, run a group buy, and I got the boards I wanted cheaper (Here's looking at you, Onion Corporation!).

    If someone knows of an assembly house that makes things like this easy, speak up. I'm getting my first ones assembled by Macrofab, but if there's enough interest, I will probably check out a place like CircuitHub or Seeed Studio.

    Anyone have any other recommendations?

    That said, this will all have to wait for my first four to arrive, so I can find out if I've totally botched the design or not.



  • @Freddy-Franco @Bas-Rijniersce

    Ah yes, Ubiquity! There's a company who's too cool to follow standards! Don't get me wrong, I'm sure they have their reasons, and some of their gear will operate on 24V non-standard PoE and/or 48V standard PoE.

    I'm pretty sure it can be made to work for 24V, although the design might need some tweaking to make everything happy. In the very least, the under-voltage lock-out is set to 35 V, so at least one resistor would have to be swapped out. There might be more complications where we have to do something special to tell the IC that it's not in 802.3af negotiation mode, but I'll test it here when I get my first boards.



  • @Freddy-Franco I usually try to run off a PDF schematic, but I forgot. Here they are now. There's a board top-layer PDF in there too, but it's a mess to look at. Sometimes there's no substitute for opening the board layout in KiCad.



  • @Mark-Martin No, just passing the existing Ethernet PHY through. Ethernet PHY's are best connected to dedicated MAC hardware in the host processor, and there's no such spare hardware exposed on the Omega for that. To have a second Ethernet jack would take an SPI-to-Ethernet MAC+PHY or a USB Ethernet adapter, and that would be a total mess (I'm talking about you, Raspberry Pi Zeros!)

    This does mean that the Ethernet expansion board won't work, but, well, I think that's fair. The four Ethernet pins on the expansion header have been replaced with four spare IOs instead.



  • I'm very interested in this. I have current generation Ubiquiti UniFi gear which is 802.3af/at compliant. If it works with that, I would possibly buy several of these.



  • Really cool! This was a feature i was asked a lot for my dock\new, but i've never implemented it. I'll be more than happy to link this project.
    Let us know how the project goes :)

    BTW i can't open the project in my kicad version. Are you on a nightly build?



  • @valerionew I'm running Kicad out of an Ubuntu repository, 201801141617+0ee38bc~61~ubuntu17.0. Sorry that it's caused headaches - if you really care, I can try to get it running in a real released version. I think there's some turmoil as they prep for the KiCad 5.0 release. I'm holding off on submitting schematic and footprint library changes until that's all done, for example.

    That said, I can also post PDF's of layers or a BOM if you'd like. I'm just worried that someone will point out some fatal design flaw after I've ordered boards. :)



  • This is great! I have a dream about making a dock with PoE and the GSM-modem but understanding KiCad is my biggest hurdle!

    But this card looks great, i so want one! :) Great work!



  • @Scott-G

    I might be interested. Depends on how testing goes



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