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TUSB522PEVM: Does this design support the interchangeability of HOST and device roles?

shibin xu
Prodigy 10 points
Part Number: TUSB522PEVM
Other Parts Discussed in Thread: TUSB522P

The typical reference schematic design features differential pairs on pins 8, 9, 11, and 12 interfacing with the HOST side's TX (transmit) and RX (receive) channels. Correspondingly, the differential pairs on pins 19, 20, 22, and 23 are linked to the device side's RX and TX channels.

Is it possible, with this design, to interchange the roles of the HOST and device ends?

1. Currently, with the reference design, the red section's USB 3.0 speed is normal, but after swapping the roles of the two ends, such as the blue section, the tested USB speed is only that of USB 2.0.

This test was conducted by directly swapping the roles of the two ends without any hardware modifications.

2. In the TUSB522PEVM User Guide, the test topology described only allows for a connection from P1 to P2, with no test results provided for role-swapped scenarios.

  • 0
    TI__Guru**** 177241 points

    Hi

    shibin xu said:
    The typical reference schematic design features differential pairs on pins 8, 9, 11, and 12 interfacing with the HOST side's TX (transmit) and RX (receive) channels. Correspondingly, the differential pairs on pins 19, 20, 22, and 23 are linked to the device side's RX and TX channels.

    Yes, but when you swapped the host and device, do you have 0.1uF capacitor on RX2P/N?

    Is it possible that you can share your schematic?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    Hi，David

    The circuit design is as follows:

    MCU is capable of switching between host and device modes. Currently, the MCU operates in Host mode and functions properly with an external device (USB flash drive) at USB 3.0 speeds. However, when the MCU operates in device mode and is connected to a PC (Host), the USB speed is only that of USB 2.0.

    Thanks,

    xu

  • 0 in reply to shibin xu
    TI__Guru**** 177241 points

    Xu

    The TUSB522P portion of the schematic looks correct. The FH34D-10S-0.5SH looks to be a flat ribbon connector, can you share the host portion of the schematic that shows the connection to this flat ribbon connector?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    Hi，David

    The circuit design is as follows:

    The motherboard is connected to this adapter board using an FPC cable, and the device is connected through a TYPE_A female socket.

    Thanks

    XU

  • 0 in reply to shibin xu
    TI__Guru**** 177241 points

    Xu

    I assume the connection is going straight the flat ribbon cable as shown below?

    If this is the case, then the connection is correct. Can you probe both sides of TUSB522P and see if you are able to see USB3 traffic?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    Hi,David

    1、During testing, a USB 3.0 high-speed flash drive was connected to the TYPE_A female port. The host computer performed read and write operations on this drive, with both read and write speeds reaching 200MB/s.

    2、When connected to a PC as the host with the TYPE_A female port, and the MCU acting as the device, it is virtually mounted as a USB drive on the PC. Read and write operations are then performed, with the speeds being around 38MB/s to 40MB/s.

  • 0 in reply to shibin xu
    TI__Guru**** 177241 points

    Hi,

    2、When connected to a PC as the host with the TYPE_A female port, and the MCU acting as the device, it is virtually mounted as a USB drive on the PC. Read and write operations are then performed, with the speeds being around 38MB/s to 40MB/s.

    A Type-A to Type-A cable is not allowed per the USB spec. Do you use a special cable that swapped TX and RX? 

    Can you please probe the TX and RX using a scope?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    I am using a USB 3.0 Type-A to Type-A cable, and upon measurement with a multimeter, it has been determined that TX and RX have been swapped.

  • 0 in reply to shibin xu
    TI__Guru**** 177241 points

    Hi,

    Can you please probe the TX and RX on both sides of TUSB522P using a scope? Are you seeing the LFPS signal at both sides?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    Hi,

    I'm sorry, but the oscilloscope on my side does not have an option for measuring USB signals, nor do we have differential probes, so it is not possible to make the measurement.

    Thanks

    Xu

  • 0 in reply to shibin xu
    TI__Guru**** 177241 points

    Xu

    Can you probe the termination on TX1/2 and RX1/2 on both sides of TUSB522P using a multimeter? 

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 10 points

    David

    Thank you for your patient explanation. I can measure the voltage signals of TX/RX using a multimeter.

    During this period, I have redesigned a test board, and the schematic and finished PCB are shown below.

    During the testing process, USB1 is connected to a PC, and USB2 is connected to a USB flash drive, which can normally recognize USB 3.0 devices with normal read and write speeds; when reversing the test, with USB1 connected to the USB flash drive and USB2 connected to the PC, only USB 2.0 is recognized, and the speed is only 50 MB/s.

    Thanks

    Xu

  • +1 in reply to shibin xu
    TI__Guru**** 177241 points

    Xu

    Looking at the schematic, it looks like you have pin 8, 9, 11, and 12 not connected correctly. Pin 8, 9 neee to connect to SSRX and 11 and 12 connect to SSTX.

    Thanks

    David