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Original question:

TUSB8041: OTP Configuration

TUSB8041: OTP for upstream USB 2.0 polarity

jonathan chapple
Prodigy 25 points
Part Number: TUSB8041

I need to flip D- and D+ for upstream USB on tusb8041.

I do not have access to i2c.

I see that downstream port polarity is configurable via OTP, but I can not find upstream in the reference.

Also, how are OTPs configured?

Changing the downstream may also work for me, but is less ideal.

  • 0
    TI__Mastermind 32981 points

    Hello Jonathan,

    You can flip the upstream polarity using the TUSB80XX efuse programming tool. Please accept my friend request on E2E and I will send you the programmer over direct message. The user manual that comes with the TUSB80XX efuse programming tool, along with the programming tool's GUI should give you everything you need to change the polarity of the upstream port. OTP's are configured through USB.

    This being said, to program the TUSB8041 through otp, you need to find a way to physically swap D+ and D- so you can connect to the TUSB8041 over USB. I see you do not have access to I2C, but if you cannot physically swap D+ and D-, you either need to program the upstream polarity over I2C EEPROM or force the TUSB8041 into SMBUS mode and program it over SMBUS.

    Best,
    Gerasimos

  • 0 in reply to Gerasimos Madalvanos
    Prodigy 25 points

    Hi Gerasimos,

    I accepted your friend request.

    Currently with D+/D- flipped, the TUSB8041 successfully enumerates as a SS device, although downstream USB 2.0 devices do not. The SS pairs are connected normally on my board. I was hoping that this would mean OTP programming of the TUSB8041 would be possible.

    Failing that, I was considering making a custom cable with D+/D- flipped as it would be far easier than reworking PCBs.

    Perhaps this will become clear when running the efuse software, but is there a way to verify the connection to TUSB8041 before attempting to program OTPs?

    Thanks,

    Jonathan

  • 0 in reply to jonathan chapple
    TI__Mastermind 32981 points

    Jonathan,

    I have sent you the message with the OTP tool. You may have to make the custom cable for the OTP, but after that you should be able to use a regular cable. You are correct, you will be able to verify connection to the TUSB8041 when you are using the OTP tool, and it should be able to read back the values if it programmed properly.

    Best,
    Gerasimos