UCTRONICS PoE HAT for Raspberry Pi 4, Mini Power Over Ethernet Expansion Board for Raspberry Pi 4 B 3 B+, with Cooling Fan

£9.9
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UCTRONICS PoE HAT for Raspberry Pi 4, Mini Power Over Ethernet Expansion Board for Raspberry Pi 4 B 3 B+, with Cooling Fan

UCTRONICS PoE HAT for Raspberry Pi 4, Mini Power Over Ethernet Expansion Board for Raspberry Pi 4 B 3 B+, with Cooling Fan

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I should mention that the PoE HAT has a little fan built into it that is positioned directly above the Raspberry Pi 4's CPU. The PoE board has a switch with two settings P0 and EN. EN seems to force the fan to run at all times, and I think P) may allow it to be turned on and off via software, but I never explored that. So I bought a replacement Raspberry Pi 4. I was able to boot it with the same SD card, with no changes to it's contents. Ubuntu came up just fine. It seemed to work exactly as the previous one had.

Eben 8:21: So we’ve built, rather than buying a transformer from somebody else, we’ve actually built our own transformer on our own PCB, and we just put a ferrite around it.I can think of one explanation that satisfies all the observations. The original HAT’s hottest point is between the HAT and the Pi itself. This is observable in the EEVBlog video linked above. I tested with the HATs installed on the Pis, making it essentially impossible to get a reading on the underside. Setting that explanation aside, my measurements indicated that the original HAT got very hot at higher power outputs, while the PoE+ HAT stayed quite stable. Above 7 watts of power output, the new HAT ran cooler as per my measurements.

The power issues were solved for the Pi 3 B+, but after the Pi 4 came out, people started plugging in more power-hungry devices like USB 3 SSDs, and the Pi's internals could draw even more power. This exposed a flaw can hit some users: the PoE HAT just can't put through all the power a fully-loaded Pi 4 needs. There are definitely similar teething problems with this next-gen PoE+ HAT, and hopefully QA for the next board's launch is better. An up to date copy of Raspberry Pi OS (and the latest kernel) is required for this HAT to function correctly. We recommend a fresh install of Raspberry Pi OS. Or maybe 2.5W if voltage and/or current is peaking higher at times. The usual max for USB 2.0 is notionally 0.5A at 5V = 2.5W. At 5.08V just 0.493A would tip it past 2.5W which isn't far off what you measure. Ok, I think I remember seeing that bit now. I can be sure these RPI4s are dead then. Thanks for helping me find that.

Now how many pixels can we turn cyberpunk purple with the PoE+ HAT? Once I hit 250 pixels, the resistance of the strip became a major factor, and increasing the driven pixels wasn’t really increasing the load. The last pixels were a noticeably different color as a result. To continue the experiment, I switched over to testing at pure white, AKA the individual red, green, and blue LEDs turned to 100% brightness. In this configuration, I was able to drive 140 pixels. The PoE+ Hat reported a maximum current of 5.4 amps, while my PoE switch showed that port pulling 30.6 watts of power, at a respectable 87.9% efficiency. The hard limit I finally hit was 5.5 amps at the HAT, at which point the Pi power cycled.

Once the PoE HAT board is connected, you can power the Raspberry Pi through its RJ45 network connector For this product to be used, the network it is connected to needs to have power-sourcing equipment installed. Unfortunately none of the published schematics from B+ onwards show any of the USB interfacing so you will likely need assistance from someone with access to the 'secret data' to pursue this further. Before installing the PoE+ HAT, you must attach the supplied spacers in the four corners of the board At the end of 2018, we released the Raspberry Pi PoE HAT, which did just this. After some embarrassing teething troubles, it has become one of our best-selling accessories. We’ve seen it used in industrial applications like digital signage and factory automation, and by hobbyists who want to put their Raspberry Pi somewhere remote, sharing a single cable for both power and data. More powerYou can use it to power your Raspberry Pi via Ethernet cable if you have a PoE capable switch or router (or a PoE injector) installed on your network. The PoE+ HAT also has a built in fan to keep your Pi's processor super cool and running efficiently. I repeated the experiment with the original PoE HAT, and you can review my raw results if you’d like. There are a couple minor caveats, mostly related to temperature measurement. My IR Thermometer doesn’t provide the rich data that a full IR camera does. Additionally, I was limited to measuring just one side of the PoE boards. I believe that the hottest spots on the original PoE HAT are on the underside of the board, while on the new HAT, seem to be on the side facing away from the Pi — that’s a win in itself. All that to say, my temperature measurements of the original HAT are probably quite a bit too low. More Launch Problems? Dominic 5:55: So the first PoE HAT was only a 13W product, and that had a much more conventional transformer on there. Eben 8:47: So this thing is a — I think there’ve been a lot of debates as to whether it’s a compliant, er — is it a compliant HAT? Is there a requirement that a HAT has PCB in all of the places that a HAT can have PCB? But yeah, so this thing is L-shaped; now what does that let us do?

So, might not be a new issue, just a reoccurence of an old one. It may not be related to the PoE HAT, just that adding one is making the issue appear in these two cases.

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And this doesn't matter to me so much, but the new HAT doesn't fit in the official Pi 4 Case. It's just a bit too big. I never use the HAT in any enclosed case so for me it's not an issue. But it is a little annoying that the old HAT did fit, while the new one doesn't. Dominic 9:34: Yes, but we needed the area. If you have a look at it, it is quite a dense board. But because we’ve been able to simplify some of the electronics now and integrate things more, especially around the area of the transformer, we’ve got this L-shaped board. And that then allows us to put it in the new Pi 5 case as well. I had my RPi 4 (4GB) running for a close to a year on the older PoE hat. Since the PoE+ released, I got hold of one and plugged it in. Although it was getting power through PoE+, the fan didn't automatically work. So I set the /boot/config.txt to have this line "dtoverlay=rpi-poe". After reboot the fan was working, without doing any update/upgrade to the OS. However, the RPi temperature was higher by a good 15-20 degree Celsius compared to the older version PoE hat and had to blast the fan to max at all times to bring the temperature down. To reduce the fan's noise, I set different temperature zones as shown by Jeff Geerling in one of his posts ( https://www.jeffgeerling.com/blog/2021/ ... essive-fan). It works to minimize the noise but the RPi temperature is hovering around 65-70 degree C at all times now. Previously it was around 45-50 degree C.



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