• State
  • Locked Locked
  • Replies 5 replies
  • Subscribers 33 subscribers
  • Views 1020 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DP83848I Evaluation Module registers cannot be read

Rush S
Prodigy 30 points
Other Parts Discussed in Thread: DP83848I, DP83848I-MAU-EK

Hi,

I am currently working on a project with a DP83848I Analog Evaluation Module PHY connected to a PIC32MZ2048ECG100 microprocessor (in the form of a Digilent chipKIT Wi-FIRE) as a MAC. However, accesses to the PHY registers using the software inside the PIC32 return 0x0000FFFF (or all ones) regardless of which register I attempt to read. The PHY is strapped at Address 1, connected in alternate configuration + MII mode. All the defaults are enabled on the PHY.

Furthermore, attempts to send a ping to the microprocessor lead to timeout. The LINK LED is active on the DP83848 module, but the ACT remains off. A loopback cable also does not light up the ACT LED. Is there a way to check the registers of the PHY itself externally, and also to see if it is communicating properly?

Thank you for your help.

Regards,

Rush

  • 0
    TI__Mastermind 31600 points
    Rush,

    Just to confirm, are you using the DP83848I-MAU-EK board (www.ti.com/.../dp83848i-mau-ek) Or is this a board of your design with the DP83848I and the PIC microprocessor co-located on the same board?

    Also, could you clarify what you mean when you note that the PHY is "connected in alternate configuration"?

    Patrick
  • 0 in reply to Patrick OFarrell
    Prodigy 30 points

    Hi Patrick,

    Yes, I am using the DP83848I-MAU-EK board connected to the microprocessor via wires connected to the interface J2.

    Alternate Configuration as in using the AExxx (AEMDIO, etc) pins of the MAC controller instead of the Exxx pins.

    Thank you!

    Rush

  • 0 in reply to Rush S
    TI__Mastermind 31600 points
    Rush,

    Could you describe the configuration of the DP83848 EVM and the connections between the boards? Which configuration jumpers are set on the DP83848 EVM? How is power provided to the board? How is ground shared between the boards? It would be helpful if you could also provide a picture of your test setup.

    Patrick
  • 0 in reply to Patrick OFarrell
    Prodigy 30 points

    Hello Patrick,

    • The configuration of the DP83848 pins through the external jumpers are as follows:
      • RMII_SEL: open (for MII)
      • LED_CFG: jumper installed (for mode 1)
      • MDIX_EN: open
      • PHYAD1: open (for address 0x1)

    • Power is provided to the DP83848 from the chipKIT Wi-FIRE microprocessor power (3.3 V) through the 3V3 pin of jumper J7.
    • Ground is shared between the same boards through an external ground pin from the Wi-FIRE.
    • Since the chipKIT Wi-FIRE does not allow for its own Ethernet connection, the MII pins are connected to the board from jumper J2 to each of the individual pins exposed in the microprocessor module as GPIO ports. If the specific pin of the PIC32 intended for MII is not readily available or is used in a different application such as an LED, it is exposed through soldering a wire to the pad directly connected to the pin in question. For now the Ethernet port is left unconnected as the start of initialization is being checked, but there is also a loopback cable available.
    • Also of note that has been discovered is the lack of activity in the AEMDC pin even when viewed through the scope. Is it possible that this may be a reason that the PHY is unable to communicate, or sends the information to the microprocessor at wrong timing?

    Thank you for your help!

    Rush

  • 0 in reply to Rush S
    TI__Mastermind 31600 points
    The AEMDC pin is the MDC serial management clock from the PIC microprocessor, correct? This clock is required for register access. If this clock is not provided by the microprocessor, you will not be able to read the PHY registers.

    Please note, when you begin testing data across the MII interface, you will need to increase the number of ground wires between the boards. I would recommend having a ground wire for every MII wire.

    Patrick