DP83848K: Unable to obtain network IP address

Hi Chen,

Is PHY link up in both cases (PC vs. router)?

Register 0x1[2] can be read to confirm link status.

In the case with DP83848 connected to computer, is communication working without error?

Thank you,

Evan

Hi Evan,

Sorry, I made a mistake. Currently, both the PC and router are unable to communicate and can only print MAC addresses, unable to obtain IP addresses. The value of the 0x10 register read is 0x7849, and the 0bit is 1. It seems that the connection is made, but the IP cannot be obtained. Could you please help analyze the reason? Thank you

Hi Chen,

For register 0x1 = 0x7849, bit [2] for link status indicates link down.

There are a few possible reasons for link down, please help confirm:

• MDI-side schematic connections (schematic can be shared privately at e-mayhew@ti.com)
• PHY is not alive
  • Probe X1 clock input to confirm valid clock (is the device in RMII master or slave mode?)
  • Probe voltage across RBIAS resistor. This should be ~1V if PHY is alive

Thank you,

Evan

Hi Chen,

Thank you for providing the inputs offline.

Regarding the schematic, the MDI-side termination circuit does not follow datasheet recommendation.

TD and RD pins require 50ohm pull-ups, as shown here:

I don't expect MDI-side signaling to be compliant for link with the current schematic design.

To confirm this, do you have a scope that can run compliance tests?

Thank you,

Evan

Hi Evan,

The customer added a pull-up resistor, but still cannot obtain the IP address. The following is the printed register information as shown in Figure 1. Please help check if there is a problem; The status change can be recognized when plugging and unplugging the network cable, as shown in Figure 2

Hi Chen,

What device is being used as the SoC?

The register log indicates link is up on the MDI side - is IP address failure occurring on both PC and router when connected?

Thank you,

Evan

Hi Evan,

The SoC is ESP32;

Yes, neither the PC nor the router can obtain the IP address.

Thank you

Hi Chen,

Thanks for confirming.

The device seems to be strapped into incorrect MAC mode. Connections indicate RMII mode is intended, but device is strapped into MII mode with no PU on RX_DV pin.

Please enable RMII mode, either through strapping RX_DV high, or by writing 0x17[5] = '1'.

Thank you,

Evan