OpenEnergyMonitor Community

Power over Ethernet?

Tags: #<Tag:0x00007f1bdcbc7920>

I’m a network guy by day, so I have PoE infrastructure for as much as possible. Having cracked open the unit, I see that the emonPi is based on a Pi 3B. Is there any reason I couldn’t drop in a 3B+ or even a 4 in there with a PoE hat that pulls power off the PoE header, and supplies the eMon board via the 5V rail? I would assume the 5V rail is tied to the USB input on the eMon board…

I am not sure the POE hat would fit and I am also not sure of the power requirements of the emonPi. There has been an issue in the past that was tracked to the use of poor quality USB cables. The Pi4 certainly needs quite a lot of power.

In general, the Pi in this setting has oodles of spare power as it is so no real need to upgrade it.

I am. :wink:
You’re right, it won’t fit.
Here’s a pic of the inside of an emonPi:

I have used this with a raspberry pi

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Oh, it would most definitely fit. it doesn’t extend past the top of the ethernet port.

While I like the PoE-Texas stuff, and have used many of them, that’s kind of an ugly solution and it is still at risk of accidental disconnection from the device.

Although it looks like it would fit, the power pins are covered and there’s no “feedthrough” pins
to power the front-end electronics. (the ATMEGA 328 and associated circuitry)

Nice piece of package engineering though!

Note, you are showing an RPi4. Also, as I said, you need to be careful about the power requirements of the additional electronics. There have been issues simply because of a poor quality cable (a good one is now supplied IIRC). How much power does the PoE, supply? In addition an RPi4 needs more power than an RPi3

802.3af PoE (which this hat supports) can supply up to 15W. I haven’t seen anything for Pi that supports 802.3at PoE+ (30W) or 802.3bt UPoE (60W) yet, (and there are future extensions planned for 95W!!!) but suffice it to say that even basic PoE can supply plenty of power. I believe the included USB supply is 10W?

This particular hat also supports the 3B+ which added those four PoE pins - It also has four pins off to the side that provide +3.3V, +5V, Power ground, and signal ground.