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TPS65988: TPS6588 with USB8041 and Type-C Data role switching

Martin Knobel
Prodigy 40 points
Part Number: TPS65988
Other Parts Discussed in Thread: TUSB8041, , TUSB8043A, TUSB8044A, TUSB8042A

I tried searching for similar use cases and I couldn't find much information, mostly likely because it's difficult to search more specifically with somewhat generic terminology.

I'm trying to design a USB Type-C hub that will be embedded in a keyboard case, It would be powered via PD from 1 of two externally facing Type-C connections, which i have planned to be controlled with the TPS6588. I was planning on having The keyboard connected via usb HS a Downstream port to of the 8041. I would like both external facing type c-receptacles to be DRPs and also Dual-Data roles.

It gets a little more complicated because I'm also planning on embedding a computer on module on the hub. I would like this to be connected also to the usb hub with a usb HS connection, while also muxing it's dsi signal to usb SS signals for the hub. So it would be a usb 2.0 and also DP source. Now the tricky part is wanting every one of the 3.1 signals being able to be to switch data roles, this would let an external host connect to the hub and control the keyboard, or an external source be only PD source allowing the embedded com to be the data host(which would in turn have the keyboard connected to it as well as outputting display signal). It's been hard finding information with USB Type-C data role switching in context of being a member of a usb HUB.

I hope this wasn't too confusing! I have a simple in progress block diagram to give a better visual

  • 0
    TI__Mastermind 27535 points

    Hi Martin,

    Thank you for the background, but is there a specific question that you have? 

    Also, for the terminology, DFP, UFP, and DRP are exclusively used to refer to the data role. Source/sink refers to the power direction

  • 0 in reply to Adam Mc Gaffin
    Prodigy 40 points

    Thanks Adam,

    Sorry about that, was caught up in the background info forgot to clearly state the problem.

    My main question is weather a usb type-c on a downstream port of the 8041 hub can switch roles from ufp to dfp or if the 8041 hub is strictly a one way data direction locking devices into the roles. I.E. a device on a downstream port of the 8041 will only ever be UFP/Client device even if it's a type-c port. I know type-c has the capability of Dual Role Data but not sure how that interacts in context of a hub like the 8041.

    My plan was to have the two external C-ports DRD and DRP, offering flexible changing of which device could be the Host device in terms of data.

    Thanks for the time,

    Martin

  • 0 in reply to Martin Knobel
    TI__Mastermind 27535 points

    Hi Martin,

    Since this seems to be a question about the TUSB8041, I am going to assign this thread to the team responsible for this device so that they can better answer your question.

    There is no problem with the PD controller acting as a DRP, and will initiate/accept data role swaps depending on the configuration you choose. 

  • 0 in reply to Adam Mc Gaffin
    Prodigy 40 points

    Thank you,

    You are right I guess It would be more about how the TUSB8041 would interact with the Type-C ecosystem (tps65988, 322, etc). This helps clarify the question a little more too.

    So if someone else is reading this on the 8041 team, how does the hub controller interact with the PD controllers when it comes to Data roles and DRP connected to the hub ic.

    Thanks!

    Martin

  • 0 in reply to Martin Knobel
    TI__Guru 60865 points

    Hi Martin,

    The TI USB hubs do not support data role swapping.  They are hard coded so that the upstream facing port is always upstream facing and the downstream facing ports are always downstream facing.  TI hubs are also completely power role independent since they don't handle any of the PD control.  

    For compliance to the most recent revisions of the USB 3.x specification, we recommend that customers use the TUSB8042A/43A/44A family of hubs, where the TUSB8042A is a standard 4 port hub, TUSB8043A is a 4 port hub with a HID interface for I2C and the TUSB8044A is a 4 port hub with HID interface and USB billboard support.

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 40 points

    Thank you!

    This is exactly what i needed to know.