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I have a device which connects to its remote using rj45 port and 4 wire cable (a desk with adjustable height). I'm pretty sure it does not actually use an Ethernet protocol and uses sends some simple digital signals. I want to Raspberry Pi to be able to control the device, so I was wondering if it is possible to read and dump and then send signals using Ethernet port just like I can do with any other pins? Probably the actual question here is about a way to bypass Ethernet driver in Linux OS.

Leo
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  • Why not breakout the pins and monitor them on an oscilloscope to see what they are doing and then patch them into the GPIO digital pins and emulate? – Mark Setchell Oct 03 '18 at 21:05
  • mainly because I don't have one and it seems to be quite expensive, especially for one time use, but I have Raspberry Pi, oscilloscopes. Basically, I wonder if I can turn raspberry into an oscilloscope with minimal efforts of soldering, ordering some parts from China etc – Leo Oct 04 '18 at 01:26
  • Sorry for necromancing, but did you manage to solve this? I have a desk by effy and searching for exact same solution. – Leo Sep 06 '21 at 01:04

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This won't work. The Ethernet NIC on the RPi - just like any other NIC - can only receive Ethernet frames. Anything else needs to be connected over GPIO.

Edit: As NO-OP has reasonably pointed out, the signals may need to be made compatible with the GPIO pins - levels adjusted, maybe an opto-isolator here and there. Nothing expensive though usually. For controlling powered devices you likely need a driver or relais board - there are plenty around for the RPi.

Zac67
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    .. the signals may also not be compatible with the Pi's GPIO levels, just as they are almost certainly incompatble with the Ethernet electrical characteristics, let alone low-level IO, and may require conditioning, conversion, and/or level shifting even when connected to GPIO's. Don't connect anything until you have measured or looked up how that connection works. Many specs can be found online. Since the Pi's GPIO specs are very well documented, you only need to find the desk's. –  Oct 07 '18 at 15:17