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TUSB8041: TUSB8041RGC

Ehud Licht
Prodigy 120 points

Part Number: TUSB8041

Hi

We have a board where the TUSB8041RGC is connected to a Y cable.

One side is only power and GND and the other is full USB 3.

The 1 and 4 pins of both connectors are physically shortened.

When connecting the power side only first and then the full USB part to the PC the hub is not being recognized, no matter what.

When connecting in reverse order e.g. full USB part first and power second there is no problem.

What can be the cause of this erratic behavior?

Rgds

Ehud Licht

  • 0
    TI__Intellectual 1350 points
    Hello Ehud,

    What are pins 1 and 4 connected to? Are they driving VBUS?

    A possible explanation to the failure is that when you plug in power first, the TUSB8041 tries to enumerate but does not see termination, and does not try again after the other USB cable is plugged in. This would explain why when USB is connected first, and then power is asserted it sees the termination and enumerates properly.

    Best,
    Gerasimos
  • 0 in reply to Gerasimos Madalvanos66
    Prodigy 120 points
    Hi Gerasimos
    Thank you for reply.
    Apparently this is the cause. I have manually reset the device after erratic situation and it helped.
    Now I need to monitor the device in order to see if it has entered the erratic mode.
    I thought to use pin #40- FULLPWRMGMTz/SMBA1/SS_UP 40 I/O, PD
    Data sheet defines this pin as ....Full power management enable/SMBus address bit 1/SuperSpeed USB Connection Status Upstream port.
    The value of the pin is sampled at the de-assertion of reset to set the power switch control
    ......After reset, this signal indicates the SuperSpeed USB connection status of the upstream port
    if enabled through the Additional Feature Configuration register. When enabled a value of 1
    indicates the upstream port is connected to a SuperSpeed USB capable port.
    How do I access the Additional Feature Configuration register?
    Rgds
    Ehud Licht
  • 0 in reply to Ehud Licht
    TI__Intellectual 1350 points
    Ehud,

    The Additional Feature Configuration Register is EEPROM configurable, or you can access it over I2C or SMBUS. The address of this register is 0xF0 and on page 27, section 8.5.22 of the datasheet you can find all the configuration options for it.

    Best,
    Gerasimos