Ethernet without RJ45 jack?

[jcw]

Would it be possible to connect a Teensy 4 to an Ethernet switch without the intermediate RJ45 jack + magnetics? I'm considering connecting a couple of them (each to its own switch port of course), and I would think that for 10..30 cm of cabling + magnetics on the switch side, perhaps the extra "stuff" could be avoided?

Another way to ask is: could a Teensy 4 be wired up directly to a cable with an RJ45 plug on the end?

[MarkT]

It wouldn't be ethernet compliant of course, but I suspect for short cable runs you could get away with it, until someone plugs the cable into a PoE sender that is.

[jcw]

until someone plugs the cable into a PoE sender

True, but that (and DC unbalance) could perhaps be solved with 0.1 µF caps in series.
There have been experiments with this approach, e.g. http://www.youritronics.com/magnetic-less-ethernet/.
It would allow plugging a Teensy 4 into a spare Ethernet jack (plus power from USB).

[jcw]

Found a related thread at https://forum.pjrc.com/threads/60846...l=1#post246596

[jonr]

Some info here:

http://ww1.microchip.com/downloads/e...ransceiver.pdf