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IMX6X and KSZ9031RNX possible or not?

Question asked by vpcb vpcb on Jul 19, 2016
Latest reply on Jul 19, 2016 by igorpadykov

Hello, I'm working on schematic where trying to connect IMX6SX and KSZ9031RNX with RGMII support.

For reference SABRESDB SX  deisgn is used.

There are some questions that I can't resolve by myself.

1. Loopback clock 125MHz

    In the SABRESD reference design Ethernet RGMII made on two AR8031 IC's with input reference clock 25MHz  from  ENET2_REF_CLK_25M signal (ENET2_RX_CLK (ALT1 option))

   But loopback clock 125MHz made optional and no information about that neither in IMX6SXHDG nor  in IMX6SXRM.

   Questions:  1. Does ENET1_TX_CLK (ENET1_REF_CLK1 (ALT1)) input support 125MHz as reference for RGMII   

                           ENET1 for IMX6SX?

                       2. Has this solution been tested by the  NXP or Freescale staff? I mean RGMII in IMX6SX

                       3. Is it good idea to use KSZ9031RNX with IMX6S? If not what IC's have been tested with IMX6SX as

                         RGMII  PHY?

                       4. Is it possible to use 3.3V as IO voltage on RGMII PHY or it must be 2.5V? I see that almost

                           nobody  except SABRESDB uses 3.3V, they use 2.5V for VDD IO of PHY?

                      5. To use both RGMIIs with IMX6SX I think the next should be done (SABRESDB SX schematic):

                           ENET_BT moved to any GPIO

                           ENET_INT moved to ENET_BT

                          ENET2_TX_CLK pin use as ENET2_REF_CLK2 (ALT1)

                          Is it right?


Thank you.