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Ethernet bring up with RMII

Question asked by Yulian Matev on Oct 6, 2016
Latest reply on Aug 9, 2018 by Mohamed Hedi BASLY


I am using X-MPC574XG-MB development board together with MPC5748G
and am trying to bring up the Ethernet module

I was able to send and receive data using the MII interface but when I try to do so via RMII I have no success.

Differences in my configuration between RMII and MII are as follows:

  1. On mother board: Jumper J7 is switched to position 2-3 so RMII Clock (50MHz) is enabled
  2. On mother board: Jumper J5 is switched to position 2-3 for RMII as initial configuration.
  3. Configuration for PHY device DP83848-EP: Register RBR (RMII and Bypass Register) is set to RMII_MODE = 1 (Reduced MII Mode)
    (It seems that point 2 already covers 3, found during debugging)
  4. Configuration of MPC5748G: Register Receive Control Register (ENET0_RCR) is configured as: RMII_MODE = 1 (MAC configured for RMII operation.) this goes together with
    MII_MODE = 1 (MII or RMII mode, as indicated by the RMII_MODE field)
    (MII_MODE = 1 is also set for the MII configuration)


Configuration of all RMII ports is kept the same as it was inside the MII configuration.

I am able to access data from PHY registers and they report that link status is OK,

but I am not able to see any data received or sent by the PHY device.

Do you have any ideas what else I have to configure?