Best board/adapter solution for PoE setup

[tehfink]

Hi all,

Sorry if this sounds similar to other threads, but I couldn't find anything addressing this topic in particular.

Setup: MicroPython boards in (relatively) remote corners of an industrial building. High power active PoE has already been/can be run to the various locations, and WiFi is not always available/desired.
Assuming a PoE splitter at the ethernet endpoints, what are the pros & cons of the various solutions? I've thought of:

1. pyboard with Ethernet adapter (eg: WIZ820IO) for data, and USB from the PoE splitter for power: would seem to be the most stable and supported solution
2. USB over Ethernet adapters at the PoE injection & splitter points: feels "hackish", worried about stability
3. some other Micropython board with Ethernet support
   • I saw a list here, but some insight as to the best board/module combination for working with ethernet would be appreciated:
     https://github.com/micropython/micropyt ... ds-Summary
   • For example, the STM32-E407 is apparently supported, but without working ethernet:
     https://github.com/micropython/micropyt ... STM32-E407

Thanks in advance!

[Lysenko]

High power active PoE has already been/can be run to the various locations,

What sort of PoE? Standards compliant (802.3af/t) PoE runs at 48V, supplies ~15-20W and requires a chipset at the end point to negotiate the power budget but there is still quite a lot of "dumb" PoE around that simply involves running 12-24V over spare[1] cores in the CAT5 cable.

I don't follow exactly what you mean by: "USB over Ethernet adapters at the injection & splitter points". Assuming you mean USB level power (5V) then you won't get more than a few meters before voltage drop becomes unacceptable.

[1] They aren't spare with gigabit Ethernet of course.

[tehfink]

Thanks for the reply!

High power active PoE has already been/can be run to the various locations,

What sort of PoE? Standards compliant (802.3af/t) PoE runs at 48V, supplies ~15-20W and requires a chipset at the end point to negotiate the power budget…

I should have been more specific; "High power active PoE" in this case means 802.3bt, 72W coming down CAT6A from a Microsemi PD-9606G:
http://www.microsemi.com/products/poe-s ... 06g-acdc-m

I don't follow exactly what you mean by: "USB over Ethernet adapters at the injection & splitter points". Assuming you mean USB level power (5V) then you won't get more than a few meters before voltage drop becomes unacceptable.

Sorry, I meant using something like TRIPP's LITE's B203-101-PNP:
http://www.tripplite.com/USB-2.0-Cat5-C ... 03-101-PNP

I haven't tested this and have no idea if it will work, but for example:
controlling computer <--> USB to Ethernet adapter <--> midspan (ie: PoE injector) <--> ethernet run <--> PoE splitter <--> Ethernet to USB adapter <--> pyboard

[Lysenko]

Sorry, I meant using something like TRIPP's LITE's B203-101-PNP:
http://www.tripplite.com/USB-2.0-Cat5-C ... 03-101-PNP

Ok, so you'll need active power extraction at the node. 802.3bt is backwards compatible with af/at in theory, but it isn't actually a standard as yet (ratification is a couple of years away) so you'll probably be best sticking to splitters from the same vendor as your switches. I have seen some af/at splitter modules that are never going to work with power applied to all 4 pairs.

I haven't tested this and have no idea if it will work, but for example:
controlling computer <--> USB to Ethernet adapter <--> midspan (ie: PoE injector) <--> ethernet run <--> PoE splitter <--> Ethernet to USB adapter <--> pyboard

That's a USB data extender. Your model seems to be trying to create a mechanism for running a pyboard interactive console at a large distance from the host PC? That is usually a development practice, not something one would field deploy.

Given that you have cabled Ethernet data infrastructure and power, I'm not sure that a pyboard/MicroPython (which doesn't support Ethernet other than via an SPI add on) is the right tool for the job. It sounds more like a job for a BeagleBone, Olimex LIME2 or an Allwinner H3 board running Linux and regular python[1]. You can leverage your existing infrastructure more easily and access a python console over SSH if you want to. The pyboard advantages of small size and low power consumption won't achieve anything in your case since your PoE splitter is going to be 5 times the size of the board and 80W is enough to power a soldering iron.

If I was absolutely set on using a pyboard for some reason then I would pair it up with a Raspberry Pi (or a clone) and connect them over a UART or USB. That way you can still remote control the pyboard over SSH without involving USB extensions or SPI Ethernet modules.

[1] MicroPython has a Linux port if you really want to use MicroPython itself.