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PoE Pi
Jul 21, 2021 11:47:42 GMT -5
Post by AudioHTIT on Jul 21, 2021 11:47:42 GMT -5
The only Raspberry Pi I’ve used is the one Emotiva sent out as part of the Dirac kit. I now have need for a Network test device, one that not only tells me a network connection works, but that also tells me a that PoE+ works. It seems to me a PoE powered Raspberry Pi would meet this need, and being ‘smart’ could possibly add other line and PoE+ diagnostic capabilities. My concern would be that the Pi won’t take much power, and without the ability to draw more current may not give me an accurate idea whether say a PoE+ camera would work … but maybe I could put it in a “Halt and Catch Fire” condition that would tell me what I wanted to know just before for it died 🙂 Of course I might find other uses for this besides networking.
So I did a quick Google and found a Pi PoE+ HAT which looks like an add on?I haven’t looked much more but are there any Pi’s that are powered natively on PoE? Maybe as an alternative to USB-C? Any recommendations where I can get up and running quickly? (the smaller the better) I used Linux quite a bit when I was working but haven’t loaded anything recently except a VM I built a couple years ago for kicks. Any Distro recommendation for this project? I used mostly SuSE and a little Red Hat in the past, but hear Mint mentioned a lot (diagnostics my focus). Thanks for your thoughts.
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Post by LuisV on Jul 21, 2021 12:20:05 GMT -5
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KeithL
Administrator 
Posts: 9,938
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Post by KeithL on Jul 21, 2021 12:25:13 GMT -5
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DYohn
Emo VIPs 
Posts: 18,348
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PoE Pi
Jul 21, 2021 12:43:57 GMT -5
Post by DYohn on Jul 21, 2021 12:43:57 GMT -5
I have one that works via WIFI called an app on my iPhone.
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Post by AudioHTIT on Jul 21, 2021 13:57:40 GMT -5
Yes, It does look like a step up from the standard cable tester, I currently use one of these KOLSOL Network Cable Tester , which doesn’t tell me PoE. I might get this as a better general tool. My current PoE tester is a Unifi mini 5 port PoE switch, if it lights up I have PoE 🙂 But I’d still like to explore the PoE Pi idea for a couple more reasons. * The Pi solution doesn’t require me unpatch the connection and stand at the patch panel to work, or stand in the hot sun out in the middle of a field where the end of my connection is. I can put the Pi in place, close the box up and remotely see how the connection is doing from anyplace on my network, typically WiFi on my iPad (possibly on the couch with a drink 🍺) * If the Pi is small enough, I can leave it hooked up in the box I’m diagnosing. * As this is a marginal line, I can check that other protocols also are working (DHCP, SSH, etc). * It doesn’t look like either method would tell me that a particular PoE+ (802.3at) device will work, but I can understand that you’ll probably need a device to ‘demand’ the voltage and current required, with the Pi I can at least see (from the Unifi controller) how much the PoE wattage on the line. I welcome your suggestions as I know you know networking, here’s the project I’m working on: Any Telco Guys Here? |
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Post by AudioHTIT on Jul 21, 2021 14:03:43 GMT -5
I have on that works via WIFI called an app on my iPhone. Not sure if your just being humorous, I also have a phone app that tells me what my switch sees on each line. But without something at the end of the line ‘exercising’ it, the information is incomplete, do you have a suggestion for that?  |
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DYohn
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Post by DYohn on Jul 21, 2021 14:52:42 GMT -5
I have on that works via WIFI called an app on my iPhone. Not sure if your just being humorous, I also have a phone app that tells me what my switch sees on each line. But without something at the end of the line ‘exercising’ it, the information is incomplete, do you have a suggestion for that? View AttachmentThe truth is I have no idea what I'm talking about so I'm just being a smart-ass. I have Net Analyzer on my phone that tells me IP addresses on the currently connected network and that's really all.  |
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PoE Pi
Jul 21, 2021 15:51:48 GMT -5
Post by AudioHTIT on Jul 21, 2021 15:51:48 GMT -5
So I guess this Pi PoE+ HAT with 802.3at is new (a few months ago), the previous solutions had af. I guess the voltage difference between PoE+ & USB (normal Pi power) makes this less than trivial. One review I saw liked it, but said it was too big to fit a standard case. I was hoping to buy a board and case and go. www.raspberrypi.org/blog/announcing-the-raspberry-pi-poe-hat/ |
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Post by AudioHTIT on Jul 21, 2021 19:59:29 GMT -5
Not sure if your just being humorous, I also have a phone app that tells me what my switch sees on each line. But without something at the end of the line ‘exercising’ it, the information is incomplete, do you have a suggestion for that? View AttachmentThe truth is I have no idea what I'm talking about so I'm just being a smart-ass. I have Net Analyzer on my phone that tells me IP addresses on the currently connected network and that's really all. I use Net Analyzer as well, nice scanning tool, and handy utilities. I use its WOL function to wake up my Mac. |
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Post by MusicHead on Jul 21, 2021 21:25:09 GMT -5
So I guess this Pi PoE+ HAT with 802.3at is new (a few months ago), the previous solutions had af. I guess the voltage difference between PoE+ & USB (normal Pi power) makes this less than trivial. One review I saw liked it, but said it was too big to fit a standard case. I was hoping to buy a board and case and go. www.raspberrypi.org/blog/announcing-the-raspberry-pi-poe-hat/The PoE voltage coming in from the Ethernet cable is always the same, whether it is PoE or PoE+. It is 48V nominal, but it can be as high as 57V (to compensate for the drop on long cables). What changes between af and at is the maximum current. Regulating that input voltage down to 5V can be very inefficient if not done right. The specs and design of this new HAT are pretty cool, with the planar transformer and the active diode bridge to reduce losses. Even more impressive that they can price it at $20. |
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PoE Pi
Jul 21, 2021 21:45:38 GMT -5
Post by AudioHTIT on Jul 21, 2021 21:45:38 GMT -5
So I guess this Pi PoE+ HAT with 802.3at is new (a few months ago), the previous solutions had af. I guess the voltage difference between PoE+ & USB (normal Pi power) makes this less than trivial. One review I saw liked it, but said it was too big to fit a standard case. I was hoping to buy a board and case and go. www.raspberrypi.org/blog/announcing-the-raspberry-pi-poe-hat/The PoE voltage coming in from the Ethernet cable is always the same, whether it is PoE or PoE+. It is 48V nominal, but it can be as high as 57V (to compensate for the drop on long cables). What changes between af and at is the maximum current. Regulating that input voltage down to 5V can be very inefficient if not done right.The specs and design of this new HAT are pretty cool, with the planar transformer and the active diode bridge to reduce losses. Even more impressive that they can price it at $20. I was trying to say something like that, I think I meant “more than trivial”. I’d love if some hardware function you could access with a Linux utility could tell you what voltage made it to the end point, though the real test is what it can do under load. |
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PoE Pi
Jul 21, 2021 22:08:26 GMT -5
via mobile
Post by MusicHead on Jul 21, 2021 22:08:26 GMT -5
The PoE voltage coming in from the Ethernet cable is always the same, whether it is PoE or PoE+. It is 48V nominal, but it can be as high as 57V (to compensate for the drop on long cables). What changes between af and at is the maximum current. Regulating that input voltage down to 5V can be very inefficient if not done right.The specs and design of this new HAT are pretty cool, with the planar transformer and the active diode bridge to reduce losses. Even more impressive that they can price it at $20. I was trying to say something like that, I think I meant “more than trivial”. I’d love if some hardware function you could access with a Linux utility could tell you what voltage made it to the end point, though the real test is what it can do under load. Uhmmm... Something like this (scroll down the page for the diagnostic commands): docs.nvidia.com/networking-ethernet-software/cumulus-linux-40/System-Configuration/Power-over-Ethernet-PoE/Unfortunately it works only on certain hardware. I am not familiar with the Rasperry PI, but I suppose that the MCU on which is based has a bunch of A/D converter. With a simple voltage divider the voltage coming through the Ethernet cable could be picked and brought within the ADC input range, measured and then made available for reading with a few simple lines of code. However, the PoE voltage level does not really matter much. Even if it sags under load to the minimum (37V), there is still plenty of margin to regulate down to 5V, provided that the source (PSE in PoE lingo) can provide enough current to sustain the required power even at the low end of the PoE voltage range. |
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PoE Pi
Jul 22, 2021 8:29:01 GMT -5
Post by AudioHTIT on Jul 22, 2021 8:29:01 GMT -5
I was trying to say something like that, I think I meant “more than trivial”. I’d love if some hardware function you could access with a Linux utility could tell you what voltage made it to the end point, though the real test is what it can do under load. Uhmmm... Something like this (scroll down the page for the diagnostic commands): docs.nvidia.com/networking-ethernet-software/cumulus-linux-40/System-Configuration/Power-over-Ethernet-PoE/Unfortunately it works only on certain hardware. I am not familiar with the Rasperry PI, but I suppose that the MCU on which is based has a bunch of A/D converter. With a simple voltage divider the voltage coming through the Ethernet cable could be picked and brought within the ADC input range, measured and then made available for reading with a few simple lines of code. However, the PoE voltage level does not really matter much. Even if it sags under load to the minimum (37V), there is still plenty of margin to regulate down to 5V, provided that the source (PSE in PoE lingo) can provide enough current to sustain the required power even at the low end of the PoE voltage range. The voltage measurement wouldn’t be to assure the Pi would run, but rather as a diagnostic of the line for suitability with bigger loads. I’m currently looking at moving a 12V, 13W camera there and it’s not trivial. ‘There’ is a very long line. This whole PoE Pi thing is really just to see what info I can gather about the connection before I move the camera, I’m also building a solar charged battery to replace the PoE if it doesn’t work. The PTZ camera works on PoE or 12V, I can always use the solar pack elsewhere if it’s not needed, fun project. |
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PoE Pi
Jul 22, 2021 10:10:03 GMT -5
via mobile
Post by MusicHead on Jul 22, 2021 10:10:03 GMT -5
As you already know 13W is the maximum power that PoE af specifies, on the load side (or PD, for Powered Device). The PSE is supposed to provide a minimum of 15W upstream of the Ethernet cable, so that (considering the worst case of the drop on 100m of cable) you get 12-13W at the input of your load. Then you have to add the losses due to the conversion from 48V down to 12V.
If you have:
- A solid PoE power supply compliant to IEEE802.3af
- Good quality Ethernet cable
- A cable run less than 100m
the camera should have no issues in being supplied via PoE.
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PoE Pi
Jul 22, 2021 10:51:28 GMT -5
Post by AudioHTIT on Jul 22, 2021 10:51:28 GMT -5
As you already know 13W is the maximum power that PoE af specifies, on the load side (or PD, for Powered Device). The PSE is supposed to provide a minimum of 15W upstream of the Ethernet cable, so that (considering the worst case of the drop on 100m of cable) you get 12-13W at the input of your load. Then you have to add the losses due to the conversion from 48V down to 12V. If you have: - A solid PoE power supply compliant to IEEE802.3af - Good quality Ethernet cable - A cable run less than 100m the camera should have no issues in being supplied via PoE. I’m using 802.3at from a Unifi switch, the camera is currently working on a ‘legal’ run (less than 100m). This new connection is not legal and can be followed in this thread: Any Telco Guys Here |
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PoE Pi
Jul 28, 2021 15:00:03 GMT -5
Post by AudioHTIT on Jul 28, 2021 15:00:03 GMT -5
So still thinking I want a PoE+ Pi, even if it’s just for oddball projects, like this. Looking around it looks like I can’t buy this all put together, so it seems I need: * Raspberry Pi 4B * PoE+ Hat * A (larger than standard) case for Pi w/PoE+ HAT * Micro HDMI Adapter (mostly for setup) Raspberry Pi Org doesn’t seem to have a case that will work, but I’ve found a couple nice ones so that’s not an issue. The real stumbler at this point is that the PoE+ HAT is sold out / on back order (one site estimated October). So unless I want to settle for a Pi 3 with older PoE HAT, this project is on hold, though I might go for it and get familiar with the build. In the mean time I built a “ Po’ man’s PoE Pi “ (it’s so po' it doesn’t have PoE 🙁). I took my Dirac Pi and powered it with a large MonoPrice USB charger I use to give me wireless charging in the car. I put it out at the street and everything connected fine. Since I can’t really get into this box I just started hitting it with 5 pings per second, and the battery lasted about 12 hours, so at lease the cobbled network seems stable. Here it is in 'the lab' (rubber band not included 🙂)  |
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Post by AudioHTIT on Aug 4, 2021 17:39:39 GMT -5
If I mention something I could use, and don’t buy it right away, my wife buys it for me. 🙂 Decided to swap the card on the Dirac Pi and buy a PoE Hat and case when they’re available, but now I also have this.  |
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