STM32F427 ETH MAC to MAC connection

marek2399 · ‎2016-11-07

Posted on November 07, 2016 at 17:46

Hello all,

i would like to ask you about possibility of connection ETH of STM32F427 directly to the another MAC device. In our application i would like to connect it directly to the MAC of CYCLONE V HPS. What do you think about it?

Many thanks for advices.

#eth #mac #stm32f27

Tesla DeLorean · ‎2016-11-07

Posted on November 07, 2016 at 18:18

For direct connectivity you would likely need a cross-over cable. You should be able to send Ethernet 802.3 packets between the boards.

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marek2399 · ‎2016-11-08

Posted on November 08, 2016 at 11:04

Hi,

you probubly did not understand me correctly. I dont want to use PHY IC. I want connect directly MII from the STM to the MII on the Cyclone V. And the distance will be minimum. Both will be on the same PCB few mm far.

waclawek.jan · ‎2016-11-08

Posted on November 08, 2016 at 11:55

You can't. MII is not symmetrical. The counterpart to STM32 would need to support what is called Reverse-MII (not to be confused with RMII).

JW

marek2399 · ‎2016-11-08

Posted on November 08, 2016 at 12:05

Hi Jan,

symmetrical you mean that TX and RX ports are not

interchangeable? Tx cannot be connected to Rx and vice versa?

Well if not how can i connect it? Does exist some kind of IC? Translator or something?.

Many thanks

waclawek.jan · ‎2016-11-08

Posted on November 08, 2016 at 14:01

Well, I'm not an expert and the devil will be hidden in the details which I'm not going to investigate at the moment, but ETH switch chips tend to have Reverse-MII as an option exactly for PHY-less connection, and I guess this is not without a reason.

JW