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Original question:

DP83848 Link Negotiation Fail

DP83848C: Auto-negotiation can't get enabled.

Xhaseem Muwakanya
Prodigy 120 points
Part Number: DP83848C

Hello everyone!

I am new to Ethernet design. We have designed a customised Ethernet Board basing on the STM32439i-eval board that uses DP83848CVV via MII.

The problem is when we run the code, it stops at auto-negotiation, and doesn't get it enabled (can't definitely be pinged). We know it's disabled by default.

Both LEDs are showing activity though. I doubt the problem is with the hardware,

Also what is the exact function of PIN 7? I know something is provided in datasheet but failed to understand it well.

Attached is the screenshot of schematics.

Thanks!

  • 0
    TI__Genius 11725 points

    Hello,

    Pin 7, the PWR_DOWN/INT pin, acts as the power down pin by default; if the pin is asserted low, the PHY is placed in power down mode. 

    When you say "when we run the code," what does this mean? You are running a script programming the registers of the PHY? Prior to running this script is link established?

    If you have register access, can you provide a read of the following registers:

    • 0x0
    • 0x1
    • 0x4
    • 0x5
    • 0x10
    • 0x11
    • 0x12
    • 0x16
    • 0x17
    • 0x18
    • 0x19

    Thank you,

    Nikhil