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Ethernet Interface and IEEE1588, 802.3 AVB

Don Lydon
Prodigy 110 points
Other Parts Discussed in Thread: AM3874

Do I need to use a specific Ethernet Interface (RGMII, G/MII, RMII) on the AM3874 to support IEEE1588, 802.3?

  • 0
    TI__Guru**** 393215 points

    Moving this to the AM387X forum.

  • 0
    TI__Guru**** 170625 points

    Don,

    Please refer to the AM387x TRM, chapter 9 3PSW Ethernet Subsystem (EMAC)

    Regards,
    Pavel

  • 0 in reply to Pavel Botev
    Prodigy 110 points

    Pavel,

    I have never used the AM3874 and I have not done an Ethernet hardware design. Chapter 9 is 159 pages long. This answer is not very helpful. I will eventually read the chapter and understand it if this part is selected for the project. Right now I do not have a day to digest it completely. I thought this type of question was what this forum was for.

    Regards,

    Don

  • 0 in reply to Don Lydon
    TI__Expert 7225 points

    Hi Don,

    Do you need AVB Rx or Tx? Also what is the end application? PLease let us know..

    Best Regards

    Feroz

  • 0
    TI__Guru**** 170625 points

    Don,

    Don Lydon said:
    Do I need to use a specific Ethernet Interface (RGMII, G/MII, RMII) on the AM3874 to support IEEE1588, 802.3?

    This is the feedback from our AVB expert:

    Our MAC ports have hardware support for IEEE1588 (of which the AVB 802.1AS is a subset) and also hardware support for queue management (Rx/Tx) and traffic shaping(Tx-only). In my opinion, the first is probably required for an AVB system, the second is helpful, but not necessarily required. For the rest, it’s all software protocols. There isn’t any requirement to use any particular interface, though on DM814x/AM387x, there is some clocking restrictions when using RGMII because the CPTS clock will be from the same source as the RGMII clock. This means you can’t adjust the CPTS clock for syntonizing to the grand master without potentially causing the 125MHz RGMII clock to go out of spec.

    Regards,
    Pavel

  • 0 in reply to Pavel Botev
    Prodigy 110 points

    Thank you very much Pavel. Your summary was exactly what I needed to understand this complicated part.

    Don

  • 0 in reply to Don Lydon
    Genius 3476 points

    The DM814x CPTS only supports layer 2 time-stamping, so you cannot do 1588 in layer 3.

    AudioScience has successfully ported the open source linuxptp to the dm8147 and is using it for 802.1AS in our AVB products.

    steve