DP83TC812R-Q1: Does RGMII interface can be compatible with RMII interface with same hardware on DP83TG720R and DP83TG812R pin 2 pin application user case?

Jing Liang

Prodigy 160 points

Part Number: DP83TC812R-Q1

Tool/software:

Hello expert,

I compared RGMII and RMII interface, the only difference is blue colored,

1.does the blue colored signal is mandatory for RMII communication?

2.Can this be used for pin 2 pin design with DP83TG720R and DP83TG812R(I mean the 2 IC share same RGMII trace and MDI signal)? if in 1000BaseT1 install DP83TG720R with RGMII interface, and if use 100BaseT1 install DP83TG812R with RMII interface.

7 months ago

0 David Creger 7 months ago

TI__Mastermind 26752 points

Hi Jing,

You have written "RMII" in the description, but attached a picture of "MII" interface. Can you please clarify which interface you are referring to?

812 supports RGMII as well, can you please let me know why that is not an option?

Thanks,

David

0 Jing Liang 7 months ago in reply to David Creger

Prodigy 160 points

I can not edit the original text, current request is MII interface with RGMII interface, can the PFY support run MII protocal on RGMII hardware trace?. Since the IBIS and drive level is different between 720R and 812R, so it is hard to make PIn2PIN design on the trace and serial resistor on RGMII signal both of them(sharing same RGMII hardware trace).

+1 David Creger 7 months ago in reply to Jing Liang

TI__Mastermind 26752 points

Hi Jing,

This could theoretically be possible. Note that in RGMII mode, MAC is driving the TX_CLK, while in MII mode, PHY is driving the TX_CLK. It should be ensured that both sides are not driving the TX_CLK at the same time.

We recommend to perform IBIS model simulation to ensure the MII/RGMII specifications are met for both cases.

Thanks,

David

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DP83TC812R-Q1: Does RGMII interface can be compatible with RMII interface with same hardware on DP83TG720R and DP83TG812R pin 2 pin application user case?