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Re: POE support on Rpi 3

Posted: Wed Mar 25, 2015 5:59 pm
by W. H. Heydt
rahlquist wrote:
bullen wrote:Also, to put a nail in the OP coffin, RPi 3 will certainly have USB type-C for power and ethernet?
Wouldn't count on that. That would require 1 of 2 things.

1. Manufacture RPi with usb 3.x and deal with the associated costs, does Broadcom make a Pi'esque chip with USB 3? Say the BCM 7445 for example, does support it on chip for example(I dont know if this could even be used to build a Pi compatible device)? Are there extra license costs with usb 3.x?

2. Figure out how to use a USB 3.x connector with a USB 2.0 controller.

For the next 4-10 years the micro usb connector will stay dirt cheap, something the Foundation might find to nice a deal to pass up. The problem is everyone wants to Pi to be perfect for their wants and its not about that, its about a cheap educational product. One of my friends was torqued because web browsing on Pi2 is still sluggish and I explained that to him again.
I don't think that follows.

If the power requirements (even optional additional power) go up, the current will exceed the rating for the microUSB connector. Since we're talking about a *power* connector, there is no logical connection to SoC support for USB 3.

The real fly in the ointment I see for using a USB-C connector is that the spec requires a chip in every cable, which is rather pointless in a power cable. Just wire it so that the power is correct no matter which way it is inserted and only wire the power pins.

Re: POE support on Rpi 3

Posted: Wed Mar 25, 2015 8:00 pm
by Bruny
this would be desirable:
USB hardware cannot be set to client mode

The UniFi®Switch features auto-sensing IEEE 802.3af/at and 24V passive PoE to power multiple devices on the network. (20V max)
mounting holes distance, of course, not same?

Re: POE support on Rpi 3

Posted: Wed Mar 25, 2015 9:30 pm
by bullen
What are the female plugs that fit the GPIO pins called?

I need to build a mesh of those!

Re: POE support on Rpi 3

Posted: Wed Mar 25, 2015 9:46 pm
by rpdom
bullen wrote:What are the female plugs that fit the GPIO pins called?

I need to build a mesh of those!
Either 20x2 way header sockets (for connecting to a PCB)
or 40 way IDC connectors (for use with cables)

Or you could use the individual Dupont connectors or just a few wires.

Re: POE support on Rpi 3

Posted: Sat Mar 28, 2015 11:45 pm
by bullen
Ok, I think I got the best solution:


Re: POE support on Rpi 3

Posted: Sun Mar 29, 2015 2:17 am
by Bruny
here also some progress for best solution on horizon!
Some even suggest to glue splitter cable to avoid misuse, but for now it is best to use surface mount box which would offer Ethernet, 2xUSB power and 24V.

Now is clear that in future there could be few USB Ethernet HATs(one completely passive powered 12V and one 24V with resistance detection).
Such module will need to refuse 48V if connected to "real" switch:
The objective of this circuit is to provide an accurate 5-V supply at the output of the DCDC converter and disconnect the supply voltage of the converter in case the supply exceeds the maximum recommended operating input voltage of the TPS62130.

In the current example the TPS62130 should be protected against overvoltage at its input. The protection should be capable of handling an input voltage up to a maximum of 40 V (VINmax). The nominal operating input voltage in this example is in the range from 12 V up to 16 V.

one of PoE Out profiles can be for each PoE Out enabled port individually:
  • auto - detection is done regarding resistance on the spare pairs to check if port has PoE capability. For port to be turned on measured value should be within range from 3kΩ to 26.5kΩ;
  • on - PoE Out is enabled on the port regardless of the resistance on the port. Use this with caution as that can damage connected equipment;

Code: Select all

[admin@MikroTik] > interface ethernet poe monitor [find]
              name: ether2 ether3 ether4 ether5
   poe-out-voltage: 23.2V  23.2V  23.2V  
   poe-out-current: 224mA  116mA  64mA   
     poe-out-power: 5.1W   2.6W   1.4W 
  • So far, less than 1% of our customers, as far as we know, have damaged their equipment.
  • VoIP technician plugged a consumer-grade 5-port PoE switch into a jack that was patched back to a $4000 48-port PoE switch. My previously over-provisioned network closet is now slightly under-provisioned.. and smells like burning

Re: POE support on Rpi 3

Posted: Sun Jan 22, 2017 11:55 pm
by sfleck

Re: POE support on Rpi 3

Posted: Mon Jan 23, 2017 7:50 pm
by mikerr
Thread is a bit old, now there are neater solutions: ... B0108TD78Y - £16.95

or ... s/8977141/ PoE HAT - £30