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Talking to the PHY with MDIO/MDC

andyy

Hey, I have a problem with the Phys of the AES-FMC-NETW1-G module. The Phys are not responding to enquirys at the MDIO/MDC interface.

 

The boards are: AES-ZU-PCIECC-G - AES-ZU3EG-1-SOM-I-G - AES-FMC-NETW1-G.

 

Attached you can see that the Phy 1 is not responding:

image

 

Actually I do not know exactly how I can go one. Normally the Phy should speak to me at address 0x01. Some ideas/hints/help for me? Do I need to enable the MDIO/MDC interface at the board?

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  • Are there several PHYs on one MDIO interface ?

    If there are they will have to be told their addresses which is often done by pin strapping.

    Are you actually addressing the correct PHY (you'll need to pick your way through the bits on the scope trace.)

    Has the board ever worked ?

    Where did you get the scope trace (ie is it at the pins of the module or PHY chip)

     

    MK

  • in reply to michaelkellett

    Hello Michael, thanks for the response. To your questions:

     

    Are there several PHYs on one MDIO interface?

    -> There are two phys at the FMC-NETW1 which are connected seperatly.

     

    If there are they will have to be told their addresses which is often done by pin strapping.

    -> From the datasheet of the phys I know that they can use the addresses from 0...7 only. So I did a loop throught all addresses. Same result... No data at MDIO.

     

    Are you actually addressing the correct PHY (you'll need to pick your way through the bits on the scope trace.)

    -> Yes I'll do. Don't know if I can record the signal with an logic analyzer. Maybe this would be the best case. At the board I come in trouble because the soldering pins are very small... Possible that I solder some additional lines for getting the signals with a clamp.

     

    Has the board ever worked ?

    -> I was using it with a realtime ethernet fieldbus ip core and yes the communication is up and running. But I had never used the management interface. I have here two completly separated board combination (FMC-NET / SOM / Ultrazed). Both have the same result. So I'm asking me if I have to activate the management interface. The ip core was working with some other phys from a different manufacturer too. But I guess if the problem is in the FPGA I do not get those signals at the phy.

     

    Where did you get the scope trace (ie is it at the pins of the module or PHY chip)

    -> I was measurering MDIO after the pullup resistor and the clock directy at the pin of the phy case. The triggering was setup to clock.

  • in reply to andyy

    I'm pretty much at the limit of general suggestions.

     

    I have had problems getting phys to come up due to reset not being cleared and pins being incorrectly strapped but you would expect a ready made board to be OK.

     

    I think you'll need to hope that one of the Avnet guys is looking.

     

    MK

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