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AM623: Feasibility Confirmation of AM623 + CC3351 Module Design and CPSW3G0 RGMII1 Mode Switching(PHY mode or MAC mode)

user6241824
Prodigy 135 points
Part Number: AM623
Other Parts Discussed in Thread: CC3351,

Tool/software:

Hi team,

We are currently designing a module based on the TI AM623 in combination with the CC3351, and we have a specific requirement regarding the CPSW3G0 RGMII1 interface. Before proceeding further, we would like to confirm the feasibility of the following implementation:

  • We need to connect the AM623 CPSW3G0 RGMII1 signals to an external device.
  • If the external device operates in MAC mode, we need to configure the AM623 via software to MAC mode.
  • If the external device operates in PHY mode, we need to configure the AM623 via software to PHY mode.

In summary, does the AM623 have registers that allow configuring the functionality of GMII pins, such as setting them to PHY mode or MAC mode?

Could you please confirm whether this configuration is achievable using the AM623? If so, are there any specific software or hardware considerations we should be aware of?

If this setup is not feasible, do you have any alternative solutions that can fulfill this requirement? We would appreciate your technical insights and recommendations.

Looking forward to your response.

Best regards,

Sheng

  • 0
    TI__Genius 17175 points

    Hello Sheng,

    user6241824 said:
    We need to connect the AM623 CPSW3G0 RGMII1 signals to an external device.

    Are you trying to attach the CC3351 to AM623 through the RGMII1 interface? 

    With the RGMII interfaces, we can support MAC-to-MAC (e.g. CPSW to an external Ethernet switch) connections or MAC-to-PHY connections. Both connected devices must support RGMII interfaces (i.e. SoC side has RGMII interfaces and the external device also has RGMII interfaces).

    The CC3351 does not appear to have an RGMII interface.

    -Daolin

  • 0 in reply to Daolin Qiu
    Prodigy 135 points

    Hi Daolin,

    • Are you trying to attach the CC3351 to AM623 through the RGMII1 interface? 

             [Sheng]We are designing the CC3351 and AM623 on the same board, connecting them via SDIO and UART.
                         The AM623's RGMII interface will be connected to an external device to enable bridge mode, data transmission, and other functionalities.

    • With the RGMII interfaces, we can support MAC-to-MAC (e.g. CPSW to an external Ethernet switch) connections or MAC-to-PHY connections. Both connected devices must support RGMII interfaces (i.e. SoC side has RGMII interfaces and the external device also has RGMII interfaces).

             [Sheng]So, does this mean that the AM623's RGMII interface cannot be configured as PHY mode and can only be used as MAC mode?

    Thanks,

    Sheng

  • 0 in reply to user6241824
    TI__Genius 17175 points

    Hi Sheng, 

    user6241824 said:
         [Sheng]So, does this mean that the AM623's RGMII interface cannot be configured as PHY mode and can only be used as MAC mode?

    Can you explain specifically what you mean by "PHY mode" and "MAC mode" in the context of the SoC side? I'm seeing that PHY mode from the external device side could mean the external device primarily functions as a PHY handling physical layer tasks and in MAC mode, the external device is responsible for taking on MAC layer functions, allowing it to directly interface with a CPU/SoC. Is this what you are asking about?

    -Daolin

  • 0 in reply to Daolin Qiu
    Prodigy 135 points

    Hi Daolin,

    Apologies for the confusion. After discussing internally, your response has already answered my question:

    "With the RGMII interfaces, we can support MAC-to-MAC (e.g., CPSW to an external Ethernet switch) connections or MAC-to-PHY connections. Both connected devices must support RGMII interfaces (i.e., SoC side has RGMII interfaces and the external device also has RGMII interfaces)."

    However, I have one more question: Is there any TRM document related to this part that you could provide for reference?

    Additionally, if the external device only supports RMII interfaces, does that mean MAC-to-MAC or MAC-to-PHY connections wouldn’t be possible?

    Thank you for your help!

    Best regards,

    Sheng

  • +1 in reply to user6241824
    TI__Genius 17175 points

    Hi Sheng, 

    user6241824 said:
    However, I have one more question: Is there any TRM document related to this part that you could provide for reference?

    For more information about our Ethernet interfaces support you can refer to the "12.3.1.2 CPSW0 Environment" section in the AM62x TRM. 

    user6241824 said:
    Additionally, if the external device only supports RMII interfaces, does that mean MAC-to-MAC or MAC-to-PHY connections wouldn’t be possible?

    The CPSW Ethernet on AM62x can support RGMII or RMII interface mode, you can find more details in the TRM. To my knowledge, there shouldn't be a restriction to MAC-to-MAC or MAC-to-PHY mode as long as both connected devices (SoC side and the external device) has the right signals needed for RMII mode. 

    -Daolin