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USB2.0 branching

Pekka Uotila
Prodigy 120 points
Other Parts Discussed in Thread: TUSB211

Dear TI Sirs,

I am designing USB testing interface. Part of the plan is to implement possibility to branch (not splitting) USB2.0 data lane between Host and Device. Target is only to be able to listen to the communication in data lane between Host and Device not to take part of communication. Plan is to connect branched lane FPGA’s High Speed Tranceiver input. TUSB211 chip will be used as USB2.0 redriver near USB3.0 connector. Distance from branching position to FPGA will be about 70mm, PCB material is high quality and used USB bit speeds are 1.5, 12 and 480MHz.

Could you please recommend solution this problem and suitable components for branching implementation?

Br Peter

  • 0
    TI__Mastermind 36085 points

    Hello Pekka,

        Unfortunately we don't have recommendations for your implementation. The USB analyzers usually split the channel to monitoring the signal so they can identify whether the information is upstream or downstream.

    Regards,

    Diego.

  • 0 in reply to Diego Cortes
    Prodigy 120 points
    Hi Diego

    I try to explain the idea more so that you can

    Idea is to sniff USB2.0 communication between USB2.0 Host and Device, send sniffed USB2.0 communication to Receiver of FPGA’s High Speed Tranceiver. FPGA only listen to USB2.0 lane and try to analyze communication so brancher/sniffer electronics should prevent any communication from FPGA side to USB2.0 lane.

    I am wondering how brancher/sniffer electronics should be done. There is much splitters (1 to 2 mux components) but only one of branches is active at at time, but not all. I have two ideas for implementations:

    1. Two USB2.0 redriver components (TUSB211?) in parallel
    2. USB2.0 redriver components and differential high speed line buffer in parallel

    and try to take care of differential impedance in both alternatives.

    How do you see these ideas, do you know any other solution for this e implementation and if above ideas will be possible to implement do you have any suitable redriver and differential high speed line buffer for this application?

    BR, Peter
  • 0 in reply to Pekka Uotila
    TI__Mastermind 36085 points

    Hello Pekka,

        The re-driver is not an option for your application, since its implementation must be with the inputs shorted to the outputs and the inclusion of the FPGA HS transceiver will drop the differential impedance below the accepted limits. I repeat, the best way yo monitor the USB activity is to split the channel as a standard USB analyzer does.

    Regards,

    Diego.