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DP83848K: Link status error for Ethernet pysical link

hiroki-okazaki
Intellectual 370 points
Part Number: DP83848K

Tool/software:

Hello.

I deverop our product implemented DP83848K.

It check Link Status register for Ethernet pysical connection.

If ethernet cable is connected, Link Status register is read of "Valid link established" always.

However, if ethernet cable is not connected, Link Status register is read of "Link not established" many,

But somtime read of  "Valid link established". Why?

Our software checks Link Status register every 150usec.

If ethernet cable is not connected, Link Status is read by the following ration.

 "Valid link established"(Error status) : "Link not established" = 1 time : 50-300 times

 

The read register is below.

Register address: 0x00 [bit 2]

Register name: Link Status

or 

Register address: 0x10 [bit 0]

Register name: Link Status

Best regards,

Okazaki

  • +1
    TI__Genius 12111 points

    Hi Okazaki-san, 

    Could you do a read on the device ID (register 0x02/0x03) before you do each read on the link status to ensure that the read on the link status is correct? We are wondering if the frequent read is causing the bus to mismatch the bit reads on the link status.

    Best,
    J

  • 0 in reply to J
    Intellectual 370 points

    Hi J-san,

    Thank you very much for your reply.

    I confirmed rea value for device ID (register 0x02/0x03) .

    In case of success,

    PHY Identifier Register #1 = 0x2000

    PHY Identifier Register #2 = 0x5C90

    In case of failure,

    PHY Identifier Register #1 = 0xFFFF

    PHY Identifier Register #2 = 0x7FFF

    or

    PHY Identifier Register #1 = 0x2000

    PHY Identifier Register #2 = 0x7FFF

    or

    PHY Identifier Register #1 = 0xFFFF

    PHY Identifier Register #2 = 0x5C90

     

    Do you have how to modification for always success?

    Best regards,

    Okazaki

  • 0 in reply to hiroki-okazaki
    TI__Genius 12111 points

    Hi Okazaki-san, 

    It looks like not every MDIO read is a success. 
    Do you have a 1.5k to 2.2k pullup resistor on the MDIO line? MDIO bus requires this pullup for the bus to function normally. 

    Could you also verify that your reads are within the setup/hold time violations below?


    Best,
    J


  • 0 in reply to J
    Intellectual 370 points

    Hi J-san,

    My puroduct has 1.5k pullup resist on MDIO.

    Best regards,

    Okazaki

  • 0 in reply to hiroki-okazaki
    TI__Genius 12111 points

    Hi Okazaki-san,

    Is R51 populated? if so, could you try after depopulating this resistor?

    Best,

    J