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Is it possible to connect some MCUs together in a star topology, without using any hub or switch? EDIT: There will be a main MCU in the star topology and it will be receiving 2 different GPS datas (From 2 other MCU's). There will be POE coming to the main MCU also. This main MCU will be sending those GPS datas to another two MCU's. All the communication will be done with ethernet. This is the network roughly.

I was thinking using splitter for POE data coming to the Main MCU and using the data of it only. 10 Mbit communication speed will be enough, the events are not that time crucial. However, for designing the circuit what kind of components I will need for the main MCU PCB. I thought there must be a transceiver but then I saw that switches also do the job of the transceivers. There will be no internet connection in the network. So I thought maybe without switches or hubs that might be possible.

Edit 2: Looks like it is doable with only using an ethernet connector.

Raxian
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  • I would say no. See this: https://electronics.stackexchange.com/a/51764/257525 – Stackoverflowsuperbad Sep 28 '20 at 06:19
  • Please edit your question and greatly improve it. Show your own work and own findings in considerable detail with any schematic. The schematic tool here is easy to use. Explain here all of what you are trying to do and why, instead of firing it off in one line then expanding your question in discussion comments as you're doing below. It's a Q&A site rather than a discussion forum. The better the quality of question, the better the quality of the answers you will attract. Thanks. – TonyM Sep 28 '20 at 07:50
  • If you control the networking stack, you can abuse Ethernet hardware into ring topology. If all the devices behave, it will work. Sort of. But it will not be Ethernet anymore. – fraxinus Sep 28 '20 at 08:02
  • @TonyM Added in edit. – Raxian Sep 28 '20 at 08:11

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You will have to use a switch IC. You could opt to not use the magnetics and cables.
You'll be on your own though, its a strange application.

Jeroen3
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  • But it says :" Ethernet switch ICs are electrical components that provide control and switching capabilities to ethernet switches. They are usually attached to the circuit board of an ethernet switch and work together with the power supply and fans to ensure optimum switching. " So I will need a switch still I guess. – Raxian Sep 28 '20 at 06:36
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    @Raxian yes, but only the chip, it can be part of your board, without cables. – Jeroen3 Sep 28 '20 at 07:02
  • So will I need both IC switch and Ethernet switch or only the IC switch? With no transceivers and anything – Raxian Sep 28 '20 at 07:04
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    @Raxian you'd need a chip in the category of LAN9355. – Jeroen3 Sep 28 '20 at 07:04
  • Thanks, but I cannot use those if the MCU's are feets apart and in different PCB's. In order to use these IC's MCU's need to be on the same PCB. Am I correct? – Raxian Sep 28 '20 at 07:05
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    @Raxian, you're now expanding your question, adding details as you go instead of at the beginning. Please see comment above. – TonyM Sep 28 '20 at 07:51
  • @Raxian If you're going to wiring you'd need to go full ethernet cabling. You can always integrate the switch chip on one of your boards so you don't need a separate device. – Jeroen3 Sep 28 '20 at 08:12