[SOLVED] GMII to MII

[Wipper]

Hi everyone,

I have an ultrascale kyntex with an SPF port and I want to implement TCP/IP communication (a Microblaze is implemented in the Kyntex).
Xilinx offers IPs to do this but we don't have the proper license to use them.

So my idea is first to convert the SFP signal to GMII with the IP "ethernet 1G/2.5G BASE-X PCS/PMA" and after connect this IP to the "AXI ethernetLite" to facilitate programming.
The problem is that "AXI ethernetLite" uses the MII interface and "ethernet1G/2.5G..." uses the GMII interface.
So my question is, is it possible to convert GMII to MII and vice versa? I think so, but how can I do this? Is it enough to "serialize" the 8bits of GMII in 4bits towards MII and vice versa?

Thanks in advance,

Willy

ps : I'm a new engineer freshly graduate so excuse me if my question is stupid, I'm still learning.

 

[dpaul]

First question, what do you like your Ethernet speed to be?

If it is 1000Mbps or less, it would be an overkill to use the SerDes lanes and then using the SPF for communication.
If your desired speed is 2.5G or more you need to use the SPF.

Then again if you use the AXI ethernetLite the supported speeds are 10/100 Mbps and if you want to use the TEMAC core (you need to pay for the full IP license) you get to choose between 10/100/1000 Mbps speed.

So I would say, first decide at what rate your Ethernet will work. That will tell which what additional components are needed.

Answering your actual question, you can either use IP cores or write you own logic to convert between GMII -- MII -- RMII -- RGMII --- whatever, this decision can come later only when you have decided on the MAC operating speed.

 

[Wipper]

Thank you @dpaul for your reply.

First question, what do you like your Ethernet speed to be?

100 Mbps is enough

If it is 1000Mbps or less, it would be an overkill to use the SerDes lanes and then using the SPF for communication.

Certainly, but the connection is optical so the PHY connector is an SFP.
But if I understand a SerDes is enough to convert GMII in MII ?

 

[dpaul]

100 Mbps is enough

Then you can use the Ethernet Lite IP core.

But if I understand a SerDes is enough to convert GMII in MII ?

No.
The purpose of SerDes is to convert a parallel stream of data to serial stream. Read the IP core spec from Xilinx.

If you can find a free to use IP cores then less work for you, else I guess you have to write your own converter IP mode for GMII <--> MII. See this -

https://support.xilinx.com/s/question/0D52E00006hpj0aSAA/gmii-to-mii-mii-to-gmii-conversion?language=en_US

 

[dpaul]

Please mark the thread as Solved if your Q is answered!