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DP83867ERGZ 100BASE-TX link down

Farhan Simjee94
Prodigy 110 points
Other Parts Discussed in Thread: DP83867ERGZ-S-EVM, DP83867E

Hi,

I am having trouble establishing a 100BASE-TX link on the DP83867ERGZ PHY. The network side is connected using two pairs A and B for 100BASE-TX mode. The SGMII is connected to an embedded network switch. The SGMII link is up and traffic on the switch port causes the activity LED to blink. The MDIO bus is accessible and shows that the link is down.

I have set the speed select bits to 100Mbps and duplex to full duplex in the BMCR register. The 1000BASE-T half and full duplex advertisement is disabled in the CFG1 register. SGMII is enabled in the PHYCR register. SGMII auto-negotiation is disabled in the CFG2 register.

All strap settings are mode 1 except for RXCTRL and LED0 which are mode 2.

I have also tried experimenting with the DP83867ERGZ-S-EVM board and see that the ethernet link comes up with four pairs but not with two. I would assume that the PHY would automatically negotiate down to 100BASE-TX when two pairs are connected. If you have the MDIO writes to configure this board to 100BASE-TX I can give that a try.

Any help would be greatly appreciated.

Here's a read out of the MDIO registers:

0x0: 0x2100
0x1: 0x7949
0x2: 0x2000
0x3: 0xA231
0x4: 0x1E1
0x9: 0x0
0xA: 0x0
0x10: 0x5C48
0x11: 0x6B02
0x14: 0x2947
0x18: 0x6150
0x31: 0x10B0
0x37: 0x2
0x43: 0x7A0
0x6E: 0x880
0x6F: 0x5

Thanks,

Farhan

  • 0
    TI__Mastermind 18425 points
    Hello Farhan,

    In both your experiments, what was the link partner for DP83867? Was it another DP83867?

    Also for checking the link up are you using register read or LED? Just a side note, Registers 0x01 needs to be read multiple times for it to show the correct link status.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Prodigy 110 points

    Aniruddha,

    The link partner is a consumer grade 8-port gigabit switch. I am looking at the LEDs on both ends: the switch and DP83867 and also reading the BMSR link status bit. I am using two 3ft Ethernet cables- one with 4 pairs and another with 2 pairs. Both cables work correctly from the switch to a PC so I know switch and cables are okay.

    At the very least, why is the eval board not linking up at 100BASE-TX with 2 pairs?

    -Farhan

  • 0 in reply to Farhan Simjee94
    TI__Mastermind 18425 points
    Hi Farhan,

    Would it be possible for you to change RX_CTRL strap from mode 2 to mode 4 and test it again? Also, please test it with both the switch and another DP83867. I tried out your config in the lab with DP83867 link partner and a Spirent Smartbits link partner, it linked up no problem in both the cases with a 2 pair wire.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Prodigy 110 points

    Hi Aniruddha,

    I tried mode 4 on the RX_CTRL but still no link. 

    I also tried these settings to better match the EVM board but no success.

    Pin Mode Setting Resistors

    RX_CTRL 1 Autoneg En open
    GPIO0 1 open
    GPIO1 1 open
    RXD0 1 PHY_AD = 00 open
    RXD2 1 PHY_AD = 00 open
    LED0 2 SGMII En 11k pullup and 2.5k pulldown and LED source
    LED1 1 SpeedSel = 1 6k pullup and 2.5k pulldown and LED source
    LED2 1 open and LED source

    I did get the EVM board to link up with two pairs. It wasn't working on one switch and took a long time on another but did get a 100Mb link.

    It could be that there is a problem with the analog front end. Is there a way to send out a test signal or loopback mode on the network side? I'll also try connecting to another DP83867E.

    Thanks,

    Farhan

  • 0 in reply to Farhan Simjee94
    TI__Mastermind 18425 points
    Hi Farhan,

    Can you try with RX_CTRL in mode 3 or mode 4? Since mode 3 has Auto-neg ON and mode 4 has Auto-neg OFF, you will have to modify your register settings accordingly.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Prodigy 110 points

    Issue resolved. The center tap on the PHY side had 3.3V supply connected which distorted the signal. This PHY does not require power to the center tap.