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DS160PR421: Two root complex support

Giorgio Delmondo
Prodigy 10 points
Part Number: DS160PR421

Tool/software:

Dear Sir/Madam,

in my application I have two root complex and one peripheral.

Before PERST# one of the two root complex is selected to be active and should be connected to the peripheral.

The other CPU will not be active.

Does the DS160PR421/412 couple fits for this architecture? Below a picture to better explain the architecture.

Thanks and Regards,

Giorgio

  • 0
    TI__Expert 7300 points

    Hi Giorgio,

    A few thoughts and initial comments.

    Is the intended idea to switch between CPU#0 and CPU#1 by using the mux selection of the devices? For example, if you want to select CPU#0 you would enable the C1 capacitor input the the top redriver and the C4 capacitor output of the bottom redriver.

    If so, that is a valid application for the DS160PR421. I recommend that you review the programming guide for more information on implementation:  https://www.ti.com/lit/ug/snlu278/snlu278.pdf 

    One note also, is the Peripheral Output lane AC coupled? I wonder why the diagram does not include a capacitor on that lane.

    Best,

    Nick

  • 0 in reply to Nick Peabody
    Prodigy 10 points

    Hi Nick,

    thanks for the feedback. I have updated the diagram (below) to better show the configuration.

    The peripheral capacitor has been omitted as already present on the peripheral.

    Yes the idea is to switch between CPU#0 and CPU#1 using the SEL input of the DS160 components.

    We have this doubt because the datasheet an manual only refer to one Root Complex (one CPU) connected to two peripherals. 

    In our case we have the opposite situation, two root complex (one enabled for each board power cycle) and a single peripheral.

    Regards,

    Giorgio

  • +1 in reply to Giorgio Delmondo
    TI__Expert 7300 points

    Hi Giorgio,

    I do not see an issue with this configuration. Out of curiosity, how often is the board power cycling?

    Let me know if you have any more questions or concerns.

    Best,

    Nick

  • 0 in reply to Nick Peabody
    Prodigy 10 points

    Hi Nick,

    thanks for your answer.

    The board will be power cycled seldom, possibly 24h/24h operation.

    The configuration of the SEL input of the MUX is fixed once the board is installed on the system.

    This configuration basically allows us to have a single board/part number for two different use cases.

    Thanks and Regards,

    Giorgio