TheRealMrChips
Posts: 5
Joined: Fri Jul 29, 2016 11:42 pm

Raspberry Pi 3 B+ PoE Hat Questions (April 2018)

Mon Apr 16, 2018 11:05 pm

All,

After looking all over I have been unable to resolve the following questions regarding the newly-announced official PoE (Power-over-Ethernet) HAT that is soon to be released:

1. Fan Control - The material released so far (see HERE) has mentioned that "Fan Control" is included in the capabilities of the hat. Great!
Question: Does anyone know what this means specifically? What GPIO pins would we use to control the fan? Are there any other means of control being included? Or does it handle this thermostatically for us?

2. GPIO Passthrough - The official photos of the hat seem to show unpopulated GPIO pin-holes on the board.
Question: Does anyone know what the final version will include regarding passthrough options on the headers?

3. Powering other devices - The official photos show "5V OUT" imprinted on the edge of the board.
Question: Is this going to be an extension of the same 5V rail that goes into the board itself, or an isolated output that can safely be used to power other devices? I'm assuming the former, but I wanted to ask to be sure.

If anyone at the foundation or in-the-know has any answers to these questions I'd love to find out! You guys are awesome and I can't wait to get my hands on some of these PoE hats to replace some bulky external adapters I'm using today. Thanks for creating wonderful things for us!

-MrChips

ShiftPlusOne
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5166
Joined: Fri Jul 29, 2011 5:36 pm
Location: The unfashionable end of the western spiral arm of the Galaxy

Re: Raspberry Pi 3 B+ PoE Hat Questions (April 2018)

Mon Apr 16, 2018 11:21 pm

1) The fan will be controlled using the standard mechanism provided by linux. It will be done through a mailbox call to the firmware, which will communicate to the board through I2C.

2) Not sure what you meean by passthrough options, but that unpopulated header is for programming and testing on the production line. If you need access to GPIO pins, you'd use an appropriate extended header.
https://thepihut.com/products/stacking- ... all-header

3) My read of that is that the 5V is just there to make it clear that the board puts out 5V to prevent people trying to get too creative with it. Not that there's an additional 5V rail. I don't have the schematic in front of me to confirm.

TheRealMrChips
Posts: 5
Joined: Fri Jul 29, 2016 11:42 pm

Re: Raspberry Pi 3 B+ PoE Hat Questions (April 2018)

Mon Apr 16, 2018 11:36 pm

Thank you so much for the fast reply!

I was not familiar with the standard I2C-based fan control process. I will do some more research to figure out the details on it.

Regarding the headers, I now realize my question could have been clearer. What I wanted to know is whether the production board will come "bare" like the photos shown, or with male pass through headers pre-soldered to it like so many other HATs do.

Regarding the 5V markings, it looks like you may be correct. I do not see any connections or solder-pads in the vicinity. Oh well, I can dream, right?

Thanks again for the info!

-MrChips

Rkreiner
Posts: 1
Joined: Tue Apr 17, 2018 7:32 pm

Re: Raspberry Pi 3 B+ PoE Hat Questions (April 2018)

Tue Apr 17, 2018 7:45 pm

In regards to question #3 does that mean you cannot power the official display in this way? I mean if the hat can provide 2.5 amp shouldn’t there be adequate power for this operations.

ShiftPlusOne
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5166
Joined: Fri Jul 29, 2011 5:36 pm
Location: The unfashionable end of the western spiral arm of the Galaxy

Re: Raspberry Pi 3 B+ PoE Hat Questions (April 2018)

Tue Apr 17, 2018 8:26 pm

TheRealMrChips wrote:
Mon Apr 16, 2018 11:36 pm
Thank you so much for the fast reply!

I was not familiar with the standard I2C-based fan control process. I will do some more research to figure out the details on it.

Regarding the headers, I now realize my question could have been clearer. What I wanted to know is whether the production board will come "bare" like the photos shown, or with male pass through headers pre-soldered to it like so many other HATs do.

Regarding the 5V markings, it looks like you may be correct. I do not see any connections or solder-pads in the vicinity. Oh well, I can dream, right?

Thanks again for the info!

-MrChips
It's not that the kernel has any i2c-specific fan control method. As far as the kernel is concerned i2c is just a bus you can connect anything to. The driver will handle the i2c communication and linux will expose a way to control the fan in a way that standard utilities understand. Afraid I don't have any specifics to give yet.

orion_jb2001
Posts: 3
Joined: Sun Apr 22, 2018 1:52 pm

Re: Raspberry Pi 3 B+ PoE Hat Questions (April 2018)

Thu Apr 26, 2018 10:37 pm

I currently am using a PI Supply POE hat on my PI3 B+, waiting for the Raspberry version to come out. Currently the PI Supply hat, cumbersome in its setup when compared with the upcoming Raspberry hat, does not connect to the POE injector (which is rated at gigabyte speeds)at gigabyte spreed then to my router.

Will the Raspberry hat, in its setup and POE use via the B+'s RJ45 port, obviously be then at gigabyte speed???

cpu123
Posts: 1
Joined: Sat Jun 30, 2018 12:01 pm

Re: Raspberry Pi 3 B+ PoE Hat Questions (April 2018)

Sat Jun 30, 2018 12:35 pm

Hi, I will use PoE pass-through switch GS105PE powered by IEEE 802.3at source. This switch can power up only one Class 0/3 PoE device or two class 1/2 devices.
Image

I will use one port for a Class 2 camera and the second port for the RPI3B+PoE HAT
As the Raspberry Pi PoE HAT is specified as Class 2 device everything looks good.

My doubts are: The IEEE 802.3af Class 2 specifies max. power 7W but the RPi PoE HAT specifies max out 5V/2.5A (15W). It looks like the the correct class is 3 instead of 2. So, will both devices connected to the switch work?

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