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3 port Gigabit Ethernet Fiber converter

ahmet.deniz , 01-31-2019, 11:36 PM
Hello Robert, I have a question for you. I need to design gigabit
ethernet fiber converter with 2 RJ45 ports and 1 fiber port. These
RJ45 ports will share time when they are communicating throug single
fiber cable. My fiber will be 1310TX/1550RX and vice versa at the
other end. I want it to be able to communicate up to 60km. So i choose
one of Marvell ethernet chips: 88E1543. My question is should i
connect sfp fiber module to its SGMII? Actually what i desire is using 1x9 1.25Gbps
BiDi transceiver but i don't know where to connect on the ic chip
(Serdes or SGMII or somewhere else). Can you help me with it? Lastly, what if i just
connect SFP fiber transceiver to SGMII and connect 2 RJ45 ports and
other ports left floating, do they start automatically communicate
with each other? Or do i need make extra things.
robertferanec , 02-03-2019, 10:16 AM
I have never done anything like this - so can not help
Paul van Avesaath , 02-05-2019, 12:12 AM
the distance of 60km has nothing to do with the controller you use. its all down to the SFP you buy .. so dont worry about that..
also how do you plan to use 2 RJ45 on 1 fiber? switch between the two?

about the floating ports you should check the datasheet for that.. but is marvell the best choice? it's pretty hard to get NDA and stuff into place to communicate with them.. (that is my experience so far)
there are also dedicated (and cheap) ready to buy items that do this..
robertferanec , 02-05-2019, 12:21 AM
there are also dedicated (and cheap) ready to buy items that do this..
Great idea! Quick search for 60km optics (not the best performance, but this was just very first result I clicked on .. there are probably more): https://www.amazon.com/Jeirdus-Ether.../dp/B07F2LM4K6

I guess, there are probably reasons why @ahmet.deniz would like to design it ... but I like @Paul van Avesaath idea ... only go with custom design if it is really required (e.g. if that it is going to be your product, long time availability is important, etc). If you are just looking for short time solution, existing products are the best way to take.
anovickis , 02-21-2019, 07:16 PM
Keep in mind 1G SFP is really 1000BASE-X not SGMII they are almost exactly the same but different :-)

Usually BiDi's are for 40G/100G+ rates not for 1G

But it looks like you have 2 x RJ45 and 1 x SFP
they don't connect without putting a switch (in the network sense) in between

I'm assuming you just want a basic switch so I would look at marvell salsa2 product (there's also things from realtek, broadcom, or microsemi etc )

you will need to NDA up on that

Of course I'm assuming you are ethernet and not some custom protocol

Salsa2 can be programmed from EEPROM on power on so you don't necessarily need a SoC to set it up

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