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DP83822H: Not able to establish 100 Mbps link.

Ajul P
Prodigy 10 points

Part Number: DP83822H

I have to configure DP83822H with my PIC32CX1025SG41128. Magnetic transformer used in design is HX1188NL. I have done the basic strap configurations for strap resistors and link is up for 10mbps full duplex. Autonegotitaion is happening for 10mbps & 100mbps from PHY side which is confirmed by reading registers values from Phy. But 100Mbps is not working. Even the 10mbps link is not stable with all laptops, but stable with D-link switch. I will share my schematics details for reference. 

Anyone have idea what is the problem here? Wether it is physical link issue or software issue?

NOTE: All resitor network values made DNP for MII Mode. 25MHz clk generated from MCU and given. Final out is given to a molex connector not RJ45.

 

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  • 0
    Prodigy 10 points

    PHY to PIC32CX1025SG41128 interface.

  • 0 in reply to Ajul P
    TI__Mastermind 36475 points

    Hi Ajul,

    A few questions:

    1. How is link status being determined? Is this read directly on PHY registers or derived from another signal?

    2. Are you writing any registers to the PHY?

    3. What is the molex connector you're using?

    4. Are you able to share the layout?

    5. I see terminations on the MDI lines, however I don't see the recommended decoupling. Can you confirm there is decoupling near these terminations?

    6. Does resetting the PHY via RESET_N affect the behavior?

    7. Is there any dependency on cable length?

    I'd recommend reading through our DP83822 troubleshooting guide for all the basic checks on the PHY. Additionally we have a DP83822 schematic checklist that shows how each pin should be implemented at the schematic level. 

    Best,

    Shane