DP83822IF: Check the schematic for customer

Hi Sulyn,

Please refer to DP83822 IEEE802.3 Compliance and Debug under Application Notes section for details on different loopback test.

Regards,

Hung Nguyen

Hi Hung Nguyen and team,

Thanks for, we are trying to follow this application note, but failed to do loopback. So still need your support to move ahead for this project.

Firstly, would you pls help double confirm below schematic to make sure these is no problem from the hardware.

Note, customer use RGMII and their design is compatible for both Copper port and Fiber port, below is the schematic and strap settings:

DP83822HF Copper port and Fiber port.pdf

2. For RGMII interface showed below, I already suggest customer to make sure the PCB trace length of TX_CLK and TX_D[3:0] are same, also make sure the PCB trace of RX_CLK and RX_D[3:0] are same, these are ok for customer. However, due to layout limitation, the length of TX pairs(Including CLK and data trace) and the length of RX pairs(Include CLK and data trace) are not same, will this be ok? Or they must be same length as well?

3. Now customer is trying to do MII loopback with copper port, but it is failed. Would you kindly suggest the detailed procedure showing how to do MII loopback?

4. When using Copper port and if we plan to do MII loopback, how to configure the pin 24(LED_1)?

5. I think MII loopback mode should not only work for MII interface, should also work with RMII and RGMII mode, is this correct? If so, any different for RGMII       interface when we want to do MII loopback.

Thanks a lot for your kindly support! Customer is pushing project schedule, need team's great support on this.

Best regards,

Sulyn

Hi Team,

Could you pls help on this customer issue which is still open and urgent?! We do need your support(Review the schematic to make sure no hardware issue) and more details(Either Hardware or software) for how to make loopback success with RGMII interface to help customer moving ahead, Thanks for your great help.

Best regards,

Sulyn

Pls kindly see my reply as below, thanks for the support.
This issue is still open and become urgent now.

Hi Sulyn,

- RGMII trace length matching is only needed within TX pins or RX pins. In other words, TX pins don't need to be length matched to RX pins.

- When you said loopback fails, what does it fail? Please also provide register configuration to enable loopback.

- Can you provide the value for the following registers: 0x467, 0x468 and 0x17

Regards,

Hung Nguyen