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TUSB2036 "Unknown Device" issue in Windows 7

Andrew Chien
Prodigy 40 points
Other Parts Discussed in Thread: TUSB2036, TPS2044

Hi there,

We are using the TUSB2036 to design a 2 port hub cape for the Beaglebone black. One USB port is to be used with a USB wifi dongle and the other a USB Zigbee dongle.

We are setting the configurable pins with the setting below:-

  • Per Port Ovrcurrent detection selected. (/GANGED pin high)
  • Self-powered hub (BUSPWR pin HIGH)
  • /PWRON1 and /PWRON2 pins are connected to /EN1 and /EN2 of TPS2044 part respectively.
  • Over current detection circuity 15k and 100nF RC filter as per EVM board with 15k pull up connected to 3.3V on /OVRCUR1, /OVRCUR2
  • /PWRON3 left unconnected.
  • /OVRCUR3 left unconnected.
  • DP3 and DM3 left unconnected.
  • /PWRSW tied to ground.
  • TUSB2036 configured as NPINT1 and NPINT0 both connected high (All ports have permanently attached devices.)
  • TUSB2036 configured as a two port hub (/NP3 pin HIGH).
  • EEPROM interface disabled.(/EXTMEM pin high)
  • 6 MHz crystal used. (MODE pin Ground)
  • SUSPEN pin left floating.

When we power up the board and connect the Upstream port to a Windows 7 laptop to troubleshoot the board, the laptop detects the USB hub as a Generic Hub and also Unknown device. See screenshot below.

For the three generic hubs listed, one of them is the TUSB2036. I know this because, I’ve checked the ID on device manager. The other two is the internal hubs on the laptop.

TI 2 port hub is shown in device manager as- Port 5, Hub 3 and the HW ID: USB\VID_0451&PID_2036&REV0101. The unknown device is shown as Port 1, Hub 5.

I can email a detailed schematic diagram for TI to verify. My questions:-

  1. As per the TI USB1.1/USB 2.0 Hub FAQ, the reset needs to be asserted for 100ns to 1ms after the VCC stabilizes(reaches 90% of full value). I looked at the TSUB2036EVM board. There a RC delay circuit there. I tried to use a RC delay of 15k resistor and 1uF capacitor in series for the reset line connected to 3.3V. This generates a delay of 36ms(by scope measurement). There is no change to the behavior of the hub when the upstream port is plugged into the PC.

What is the recommended timing values for the /RESET line?

 

2. Why is there a Generic Hub and Unknown device showing at the same time in the device manager?

3. As per the TI USB1.1/USB 2.0 Hub FAQs, the OVRCUR and PWRON pins are recommended to be tied high. On my design, I’ve selected /NP3 LOW thus only two port operation. So should /OVRCUR3 and /PWRON3 be connected high?

 

4.Should DP3 and DM3 be connected to ground if only 2 ports are used? FAQ says yes, and I’ve tried it but no difference in the behaviour.

5. Would NPINT1 and NPINT0 be set to low instead of high as we are using USB dongles?

Hope to hear from you soon.

Andrew

  • 0
    TI__Mastermind 18655 points

    Hello Andrew,

    Actually, as per USB 2.0 spec an USB device must respond before 100ms after 3.3V Vcc reaches its 90%. For that reason is used external RC circuit is used (15K pull-up resistor and 1 uF cap).

    Please, follow the datasheet suggestion: "Generally, a reset with a pulse width between 100 μs and 1 ms is recommended after 3.3-V VCC reaches its 90%.".

    Even if the TUSB2036 is configured to use 2 ports, all unused inputs or ports must be connected to a high or low bias to prevent them from floating.

    The DP and DM signals of the unused port should be tied to ground with 15K resistors like the pull-downs used on the active ports.

    The OVRCUR/ input of the unused port can be left tied to the other OVRCUR/ inputs if the hub is configured as GANGED. If the hub is not configured as GANGED, OVRCUR/ input of the unused port should have a pull-up resistor. A value of 1.5K is sufficient.

    The PWRON/ output can be left unconnected.

    Note: Connecting the unused ports to ground is the recommended solution; it will not negatively impact the device.

    NPINT1 and NPINT0 can be tied to ground.

    Please, send me your sechematics to joel.jimenez@ti.com

    Regards.