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Original question:

TUSB8041: "No attached TUSB840 device was found" error

TUSB8041: Forcing Programming Mode of TUSB8041 and Pin Signals

Sarah Weinberger
Expert 1915 points
Part Number: TUSB8041

Is 4.7K okay for the pull-up of SDA/SCL I2C/SMBUS signals?

Do we need to pull pin 39 (SMBUSz/SS_SUSPEND) down to program the EEPROM? Right now, we are not using pin 39. The default is PU. Do we need to do anything with register 0xF0 (Advanced Configuration Register), which enables this mode?

This question relates to my other two questions on how to program the EEPROM. I would like to use the USB interface and the Windows applet. In order to do that, I need to enable programming mode, hence this question.

Enabling Programming Mode

There are three conditions that will enable programming mode:
1) A blank EEPROM is present and functional
2) An EEPROM is present in which address 0x00 = 0xFF
3) Programming mode has been externally enabled.

Forcing document: Step 4: Open the programming tool. Pullups must be installed on SDA and SCL to program an EEPROM.

  • 0
    TI__Intellectual 1350 points

    Hello Sarah,

    From reading through your previous post, I believe you haven't connected an external EEPROM to your TUSB8041. There is no internal EEPROM in the TUSB8041, which is why the endpoint isn't set.

    You need to connect an external I2C EEPROM to the SDA, SCL and GND lines from the TUSB8041. The rest of the connections on the EEPROM should be in the datasheet of whatever EEPROM you choose to use. Once you connect this EEPROM to the TUSB8041, the programming endpoint should appear.

    For any suggestions on what sort of wiring or pull-up resistors will work on the TUSB8041, please see the evaluation module schematic, which I have linked for convenience.sllc460.zip

    Best,
    Gerasimos

  • 0 in reply to Gerasimos Madalvanos66
    Expert 1915 points

    Hi Gerasimos,

    Great reply, thank you, however you did not address pin 39, which our electrical engineer specifically requested. He was not sure about that line.

    Yes, you are correct. The original spin of the board forgot to add the EEPROM. The EE ordered an EEPROM, which will arrive on Monday and then get installed onto my board. I presume that means rework/respin on all future boards, oh well.

    Additionally, my other question were not answered in the other thread.

    • There are 2 product strings: USB 2.0 product string and USB 3.0 product string, but only one product string on the setting. Do both the USB 2 and 3 product strings now use the same product string or does something get appended to it?

  • 0 in reply to Sarah Weinberger
    TI__Guru 60870 points
    Hi Sarah,

    Pin 39 is only enabled (pulled down) if a SMBUS host is used. If you are installing an external EEPROM, SMBUSz should be left in its default state.

    The hub will report the same product string for both instances of the hub (USB 2.0 and USB 3.0).

    Regards,
    JMMN