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AM572x IBIS Models queries

Shareef
Expert 1985 points
Other Parts Discussed in Thread: AM5728

Hi,

Please help me in choosing the right IBIS models for SI analysis of certain interfaces whose model selection is not clear from the AM5728 TRM.

1. For AM5728 PCIE_TX/1 has Selector_6 as model name. The actual submodel used should have the right deemphasis settings and voltage level along with speed.

a. I believe speed is HS and voltage is 1.2V
b. However it is not clear of what is the deemphasis setting of PCIE PHY?

- The PCIe PHY registers have deemphasis bit which is set to 1 and is read only. Not sure what is the settings corresponding to this register value.

2. Above holds true for USB 3.0 port of AM572x. Please share more information on the correct IBIS model to be used,

3. For Model Selector_5, the sub-models have Slew rate which can be easily found out from reading pad control registers of a pin. However what is not clear is the parameter IND,10 PERCENT% or 5%. How should one choose the same?

Thanks and would appreciate a quicker response from TI experts.


Regards,

Shareef

  • 0
    TI__Guru**** 393215 points
    Hi,

    I will forward this to the IBIS experts. Feedback will be posted here when available.
  • 0 in reply to Biser Gatchev-XID
    Expert 1985 points
    Hi Biser,

    Thanks for forwarding. Looking to get a sooner response from IBIS experts.

    Regards,
    Shareef
  • 0 in reply to Shareef
    TI__Guru*** 140015 points

    Shareef

    For USB3, please use model_190, 191, or 192. The difference between the model is half swing (HS) or full swing (FS), and no de-emphasis or 3.5dB de-emphasis.

    For PCIe, it is the same, it is better to sweep the different model since the model behavior is depending on the channel characteristic under simulation. You can set de-emphasis to 3.5dB or 6dB for PCIe interface.

    Let me take a look at questions #3 and get an answer for you as soon as possible.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Expert 1985 points
    Hi David,

    Thanks. I don't see a user has configurability in software to change the USB and PCIe PHY parameters. So please tell me what is the default settings of the following serial interfaces w.r.t Signal swing and De-emphasis mode.

    1. USB TX
    2. PCIE TX

    This is required to know because I would like the SI analysis models to match the actual hardware settings. Also in case there is configurability to the user through software then I would like to know the registers in TRM and what is their default settings for both USB 3.0 and PCIe 2.0. Thanks for your help again and look forward to your quick response.

    Regards,
    Shareef
  • 0 in reply to Shareef
    Expert 1985 points

    Hi David,

    Any update on this?

    Regards,

    Sharef

  • 0 in reply to Shareef
    TI__Guru*** 140015 points

    Sharef

    For the last question, 10% and 5% refer to I/O voltage tolerance.

    There are 8 models in selector 5, they differ by 3 parameters that have two options each (2^3 = 8)

    -          IO voltage (1.8V or 3.3V)

    -          Slew rate (fast or slow)

    -          Voltage tolerance of the IO supply

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Expert 1985 points
    David,

    Thanks for answering on question #3. Can you please provide update to my later questions based on USB and PHY TX?

    Regards,
    Shareef
  • 0 in reply to Shareef
    Expert 1985 points

    Hello David,

    Is there any update to share?

    Thanks,

    Shareef

  • 0 in reply to Shareef
    TI__Guru*** 140015 points

    Shareef

    What are you trying to accomplish here? Are you trying to use simulation to find the best setting for your system?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Expert 1985 points
    Hi David,

    Yes, we are trying to see if the simulation results with the default HW settings meets the specification or not.

    To be honest from the AM5728 TRM, I don't see a way to change the setting for Signal swing and De-emphasis modes of both USB & PCIE PHY. Hence, I am requesting you to share the default PHY settings so that I will come to know if the simulation results are fine.

    Thanks,
    Shareef
  • 0 in reply to Shareef
    TI__Guru*** 140015 points

    Shareef

    For PCIe, the controller directly controls the PHY de-emphasis level using the Compliance Pre-set/ De-emphasis bit field for EP and RC.

    For USB, the de-emphasis and swing control are not available from the controller level.

    The model provides swing and de-emphasis selection options, these are only debug options through the PHY.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Expert 1985 points
    David,

    Many thanks for sharing the details. May I know the default Settings for USB PHY TX with regards to below parameters

    1. De-emphasis – No or 3.5dB de-emphasis
    2. Swing - half swing (HS) or full swing (FS)

    Similarly can you tell me the description for values for bits 15:12 COMPL_PRST_DEEPH fiekd for PCIe TX PHY. The default values for these bits in TRM are 0x0. What does this mean?

    Thanks,
    Shareef
  • 0 in reply to Shareef
    Expert 1985 points

    Hi David,

    Do you have any update to share on my above post?

    Thanks,
    Shareef