• State
  • Replies 1 reply
  • Subscribers 33 subscribers
  • Views 55 views
  • Users 0 members are here
Support feedback
Options
Options
Related

Original question:

TUSB320LAI: USB-C compatibility issue with some laptops when interfacing with TUSB320

TUSB320HAI: TUSB320 USB C-to-C compatibility issues

Thuso Tshishonga
Prodigy 10 points
Part Number: TUSB320HAI
Other Parts Discussed in Thread: TUSB320

Tool/software:

I am facing USB C-to-C compatibility issues with some laptop brands. I am using the TUSB320HA device with the Port pin left open to select DRP mode by default. I am experiencing the following issues when attempting a USB C-to-C connection to a laptop:

- No connection made, the laptop does not detect the USB connection. TUSB320 register 0x09 also shows no attachment.

- For some laptop brands, the TUSB320 register 0x09 shows it attached as DFP SRC while the laptop has not detected the USB connection.

- For some laptops, the TUSB320 device successfully attaches

I have tried placing the TUSB320 device in UFP mode using I2C, but the behavior still remains the same. This connection issues are not observed when using a USB C to USB A connection. A power cycle also resolves the issue, the TUSB320 device attaches a USB C-to-C connection if the cable is connected before power is switched on. 

  • 0
    TI__Mastermind 38955 points

    Hello,

    Can you monitor the CC pins before and after the TUSB320HA connects to see what the status of the CC pins is? Since the TUSB320 is set as a DRP, the CC lines should be toggling high and low before a connection is made.

    Thuso Tshishonga said:
    - No connection made, the laptop does not detect the USB connection. TUSB320 register 0x09 also shows no attachment.

    This is just setting a baseline for what you are seeing before you connect the two devices, correct? Or are these connected at this time, but there is no indication on the laptop?

    Thuso Tshishonga said:
    - For some laptop brands, the TUSB320 register 0x09 shows it attached as DFP SRC while the laptop has not detected the USB connection.

    If both the laptop and the TUSB320 are set as a DRP, then it is very possible the TUSB320 can configure as a DFP. This will likely cause the laptop to not detect the TUSB320, while the TUSB320 may try to provide power to the type-C port as if connecting to a device. Unfortunately, if both ports are set as DRP, there is no way to guarantee how the TUSB320 will configure, though you can configure the TUSB320 to try to bias it when acting as a DRP in register 0x0A[2:1].

    Typically, forcing the TUSB320 to act as a UFP would fix this issue, so long as the laptop port can act as a DFP. Are you changing the TUSB320's register before a connection is made? Any changes made to the TUSB320 registers should be made while there is no connection. Can you monitor the CC pins after setting the TUSB320 to a UFP? These pins should go down to 0V.

    Thuso Tshishonga said:
    This connection issues are not observed when using a USB C to USB A connection.

    A Type-C to type-A forces the type-A side to act as a DFP, supplying voltage to the CC pins. This will cause whatever is on the type-C side, assumingly the TUSB320HA, to configure as a UFP, so the functionality there seems correct.

    Thuso Tshishonga said:
    A power cycle also resolves the issue, the TUSB320 device attaches a USB C-to-C connection if the cable is connected before power is switched on. 

    Is the TUSB320 configuring as a UFP in this scenario? If so, it is likely due to dead battery mode.

    Thanks,

    Ryan