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TUSB2E22EVM-CAT: Host PC device driver is showing as Unknown USB device (Device Descriptor Request Failed)

Jaykumar Khatke
Prodigy 10 points
Part Number: TUSB2E22EVM-CAT
Other Parts Discussed in Thread: TUSB2E22

Hi, I am trying to enable the eusb2 repeater using TUSB2E22EVM-CAT module.(eUSB2 to USB2)
I am following the below steps:

Connecting Host to repeater--> enables VBUS(powering ON the EVM with VBUS only)

  1. Reset the repeter
  2. enable the device eusb PHY in HS mode & start sending some HS Test packets.
  3. The Host PC device manager shows the detection of device but gives error as Unknown USB device (Device Descriptor Request Failed)
  4. Tried with different EQ levels and both the channels, shows same behavior.
  5. I confirmed the input eusb2 packets from PHY to repeater on scope.
  6. Same baehaviour observed for FS speed also
  7. Attached is the block diagram of the setup. 
  8. image.png
  9. FYI eusb2 device is our QC eusb2 PHY,(no controller enabled), But phy sends eusb2 packets
  10. please let me know If I am missing any step. or let us know what the repeater expects to covert it to USB2 signals & can be detected  in Host PC as USB2 device.
  11. Also please feel free if you need more info on setup.
  • 0
    TI__Mastermind 43555 points

    Hi Jaykumar,

    For clarification, what configuration are you using this in? Is this a USB2 host connecting to an eUSB2 device, per your block diagram? Is the eUSB2 device sending the test packets, or the USB2 host?

    The eUSB2 device should be configuring the TUSB2E22 as a device via the eDP/DM. 

    Jaykumar Khatke said:
    enable the device eusb PHY in HS mode & start sending some HS Test packets.

    What do you mean by enabling device eUSB PHY? Do you mean powering the PHY? Is the PHY configuring the repeater before sending these test packets?

    Jaykumar Khatke said:
    The Host PC device manager shows the detection of device but gives error as Unknown USB device (Device Descriptor Request Failed)

    If test packets are coming from the repeater, then the Host PC should not even detect the device. The fact that it does detect it indicates that it is likely seeing terminations from the repeater board, but no actual signaling. Would it be possible to monitor the USB lanes while test packets are being sent to confirm whether test packets are making it through the repeater or not?

    If there is no signaling on the USB side, then its likely that the repeater is not configured to device/peripheral mode.

    Jaykumar Khatke said:
    FYI eusb2 device is our QC eusb2 PHY,(no controller enabled), But phy sends eusb2 packets

    What do you mean by "no controller enabled"? Is there no controller setting the mode of the TUSB2E22? Typically, the controller is in charge of configuring the mode of the repeater via the eDP/eDM lanes.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 10 points
    Ryan Kitto said:
    For clarification, what configuration are you using this in? Is this a USB2 host connecting to an eUSB2 device, per your block diagram? Is the eUSB2 device sending the test packets, or the USB2 host?

    Yes, USB2 Host(PC) is connected to eusb2 device through repeater. eUSB2 device is sending the HS test packet to repeater.

    Ryan Kitto said:
    The eUSB2 device should be configuring the TUSB2E22 as a device via the eDP/DM.

    Could you please provide more details on the following point: “The eUSB2 device should configure the TUSB2E22 as a device via the eDP/DM interface.” What are the specific steps required from device to achieve this configuration?


    Ryan Kitto said:
    What do you mean by enabling device eUSB PHY? Do you mean powering the PHY? Is the PHY configuring the repeater before sending these test packets?

    Yes, the PHY is powered ON & ready to send the packets. However, it is not configuring the repeater before transmitting these packets. Could you please clarify what configurations are required on the PHY side to enable this?

    Ryan Kitto said:

    If there is no signaling on the USB side, then its likely that the repeater is not configured to device/peripheral mode.

    We attempted to check the USB2 signals using a Keysight termination board, but no signal was observed on the oscilloscope.

    Ryan Kitto said:
    What do you mean by "no controller enabled"? Is there no controller setting the mode of the TUSB2E22? Typically, the controller is in charge of configuring the mode of the repeater via the eDP/eDM lanes.

    We are currently testing in PHY-alone mode, so the controller has not been enabled. Is it possible to configure the repeater without the controller, using only PHY signals?

  • 0 in reply to Jaykumar Khatke
    TI__Mastermind 43555 points

    Hi Jaykumar,

    Jaykumar Khatke said:
    We are currently testing in PHY-alone mode, so the controller has not been enabled. Is it possible to configure the repeater without the controller, using only PHY signals?

    The controller is required in order to configure the repeater, if there is no controller setting the repeater then the repeater will not enter device mode, and will not send the test packets through to the USB2 pins, hence why the scope is not seeing any data on the USB2 lanes.

    One way to confirm whether there is any communication between the eUSB2 PHY and the repeater before test packets are sent. If not are sent, then the repeater is likely not being sent.

    Section 5 of the eUSB2 spec outlines the process for repeater configuration and operation.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    TI__Mastermind 43555 points

    Hello,

    Closing thread due to inactivity. If you have any follow-up questions or concerns, feel free to reply.

    Thanks,

    Ryan