DP83867IR: Not able to detect the device on MII bus

Hi Ashish,

I see a few possible causes:

1) Value of resistors R156, R161 (confirm RX_D6 strap mode 3/4 for RGMII disable)

2) Missing TX_CLK, RX_ER, TX_ER connections to MAC for MII mode. CRS/COL connections also missing for MII, but these should not be required for MAC to recognize device.

To resolve (1), please test with either mode 3/4 on RX_D6:

If possible, please also share PHY register dump to confirm the correct strap config is set.

Whether (2) is the root cause is unclear - which device is being used as MAC? We may need to check with MAC vendor to confirm if MII device can be recognized with the existing connections. I am mainly concerned with GTX_CLK used instead of TX_CLK for MII mode.

Thank you,

Evan

Hi Evan,

Thanks for the detailed reply .

We are using the device in  RGMII mode. By MII bus I meant MDIO/MDC.

DP83867IRPAPR is connected to XCZU9EG(schematic is attached)

Please help.

Regards,

Ashish

Hi Ashish,

Thank you for clarifying.

Which PHY address is XCZU9EG looking for on the MDIO/MDC bus?

From schematic, PHY looks to be strapped with PHY address 0. However, it's possible the MAC is driving these lines on startup and affecting the strapped PHY address.

Could the voltage across RBIAS resistor (R139) be measured? This should be roughly 1V to confirm the PHY is alive.

Best regards,

Evan

Hi Evan,

We are looking for address 0.

Voltage across R139 is 0.27 V. It seems PHY isn't alive despite CPR(Clock,Power,Reset) being properly applied.

How to bring PHY alive?

Regards,

Ashish

Hi Ashish,

Is it possible to share a scope capture of clock/power/reset signals when PHY is powered?

I'd like to verify power sequence.

Do you see this issue on multiple boards?

Thank you,

Evan