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the schematic of DP83848IVV

chenping song
Prodigy 60 points

sir:

i have finished a schematic for the DP83848IVV, using RMII interface. and i want to know if it correct, and if the pin-39 must be connected to MCU?

  • 0
    TI__Mastermind 31600 points

    Connecting RX_DV (pin 39) to the MCU is not required.  The RX_DV signal is not part of the RMII specification, but it is provided to simplify recovery of receive data for those systems that can take advantage of that functionality.  The RMII application note (http://www.ti.com/litv/pdf/snla076) provides a little more detail on this if you are interested.

    Patrick

  • 0 in reply to Patrick OFarrell
    Prodigy 60 points

    hello Patrick:

    Thanks for your reply mail, but now  we have a problem, if we don't connect the pin_39 to the MCU, the communication of the Ethernet is wrong. and it is ok when we connect the pin_39 to the MCU. we don't know why? the MCU is STM32F217. i can send the schematics of the connection between the DP83848IVV and MCU.

     

  • 0 in reply to chenping song
    TI__Mastermind 31600 points

    The Phy portion of the schematic looks correct.  I do not see any issues there.

    I am not familiar with the functionality of the STM32F217 so I cannot comment on how it handles the RX_DV input in RMII mode.  Are you connecting the Phy RX_DV signal instead of the CRS_DV signal or are you connecting both of them to separate MCU pins?

    Could you elaborate on what you mean when you note that "the communication of the Ethernet is wrong"?  Does the Phy link?  Can it transmit to a partner?  Receive from a partner?  Some details on this could help in debugging the issue.

    Patrick