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USB2ANY: USB2ANY with LMP92066 - How to disable Pullups on I2C??

Dan Meeks
Prodigy 10 points

Part Number: USB2ANY
Other Parts Discussed in Thread: LMP92066, , LMP92066EVM, MSP430F5529

Tool/software:

Trying to use the USB2ANY with LMP92066 bias controller. Seems to have a lot of bugs... but was working through that and realized that the I2C lines in the USB2ANY are pulled up too high. OUr target LMP9266 is on 1.8V I2C bus. The USB2ANY manual says that pullups can be disabled but offers no help on how to do that.

Related question - the USB2ANY seems to imply that the I2C levels must be 3.3V. Is that true? In that case, will I be able to program my LMP9266 on a 1.8V I2C bus without isolating the IC from the bus on the board?

To be clear, the LMP92066 is on a final target board. There are no masters on the bus (sort of, there is a multimode master so it should not be interfering).

Quick resolution is appreciated. We are on a time crunch.

Thanks in adavance.

  • 0
    TI__Genius 17440 points

    Hi Dan,

    What program are you using to interface with the USB2ANY? I don't believe there is any way to turn off the pullups in the LMP GUI. The USB2ANY GUI, though, does have an option for turning off pullups. I'm not sure if you'll be able to readback from the LMP with a 1.8V VIO, but you can write.

    Thanks,
    Erin

  • 0 in reply to Erin Bowrie
    Prodigy 10 points

    More info. The I2C lines never toggle. I bought a second unit and it's the same.

    I am trying to use it with your LMP92066EVM GUI.

    I disconnected my target board and provided pullups externally, scoped them, and nothing They both just stay high.

    I see some mistakes in the docs:
    1. transistors shown wrong (the ones that enable the pullup resistors, the body diodes are backwards).
    2. the header J4 pinout on the board is backwards for the cable. Pin 10 on board is pin 1 on cable. Very confusing looking at the docs.
    So why don't the I2C lines toggle? 

    And yes I have verified that I am on the right pins - I took the cover off and ohmed back to the MSP430.

    Also shame on you for having 3.3V pullups, it makes it very NOT universal. I am calling it the USB2???

    Thanks 

    Dan

  • 0 in reply to Dan Meeks
    TI__Mastermind 42253 points

    Hi Dan, 

    The USB2ANY is primarily meant to be a controller for TI evaluation modules, not a programmer for custom boards. Our eval board uses 3.3V logic, so we take advantage of the 3.3V pullups in the LMP92066EVM GUI. The MSP430F5529 in the USB2ANY uses a fixed 3.3V supply, so 1.8V logic is likely not supported, you won't be able to read as Erin mentioned. 

    Have you ever been able to use the USB2ANY with the LMP92066EVM GUI on your computer? Putting aside the pullup conversation, are you sure the GUI is installed correctly and the USB2ANY is connected to your computer? Do you see the "connected" status at the bottom of the GUI? 

    Best,

    Katlynne Jones