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TUSB546EVM: Basic setup and accessing the I2C registers of the TUSB546

Abhijit Ray
Prodigy 50 points
Part Number: TUSB546EVM
Other Parts Discussed in Thread: TPS65982, , TUSB546-DCI

Hi,

I wanted to access the I2C registers of the TUSB546 housed on the TUSB546 EVM.I should be able to talk to the TUSB546 I2C registers directly ( without the TPS65982 as master) via the SPI Programming Interface on the EVM.( which has the SDA and SCL lines coming out).For that to happen, the only requirements are:  the I2C_EN must be made high and proper connections must be made(via connection of zero ohm resistors) from the SPI programmer header to the TUSB546.

The above are correct assumptions, right?

Also the documentation and user guide available on ti.com ( http://www.ti.com/tool/tusb546evm ) for the usage of the EVM seems unable to tell how to get it up and running for the first time with the basic connections.  

Is there a basic user guide available which I can use for this purpose?

 

Thanks

Abhijit Ray

  • 0
    TI__Mastermind 23815 points
    Hi Abhijit,

    The TUSB546EVM has an I2C interface, refer to datasheet's section 8.5 for details about I2C programming.
    The SPI interface in the EVM goes from TPS65982(master) to W25Q80(slave), you could use the TPS65982 to control other SPI devices or to write to W25Q80 using a different master.

    Regards
  • 0
    TI__Mastermind 36085 points

    Hello Ray, your assumptions are correct, you only have to ensure that the TUSB546 I2C address is correct.

    Regards,

    Diego.

  • 0 in reply to Diego Cortes
    TI__Prodigy 50 points

    Thanks Diego,

      When I  connect the Aardvark to the SPI programming interface header on the TUSB546EVM, I observe that the I2C lines (SDA and SCL) are being pulled low( should be pulled high) and no I2C traffic is captured when I write something from the Aardvark GUI.

    I have confirmed that this is not due to a faulty Aardvark as I have tested the Aardvark separately and it is pulling the lines high as expected.

    Is there any other component on the EVM board that I may have missed which may be pulling the I2C lines low?

    Thanks and Regards

    Abhijit Ray

  • 0 in reply to Moises Garcia
    TI__Prodigy 50 points

    Thanks Moises.

    I am still seeing an issue when I try to talk to the TUSB546 directly via I2C using an Aardvark.

    The lines are being pulled low as I have explained in my reply to Diego.

    Regards

    Abhijit

  • 0 in reply to Abhijit Ray
    TI__Mastermind 23815 points
    Hi Abhijit,

    Could you measure the voltage in I2C lines after reset and without Aarvark?

    Regards
  • 0 in reply to Moises Garcia
    TI__Prodigy 50 points

    Hi Moises,

    This above circle is the SPI Programming Header that I had connected the Aardvark to, as it has the I2C lines as found in the EVM schematic below:

    From what I understand, using these I2C lines, we should be able to talk and access the registers of the TUSB546 directly housed on the EVM.

    In response to your query, I measured the voltage on the I2C lines (pins 1 and 3 in the figure above) without the Aardvark and on reset.

    It came to be around 10mV. It seems they are low.

     

    • Is there any other test point I can use for measuring these voltages?

     

    • For powering the board, connecting the EVM to my computer via the USB type B cable (J4 on the EVM) is enough to power it , right?

     

     Thanks and regards

    Abhijit

  • 0 in reply to Abhijit Ray
    TI__Mastermind 23815 points
    Hi Abhijit,

    I have reviewed the EVM, it seems TUSB546-DCI was intended to be controlled by TPS65982 by GPIO, however, the I2C lines are connected to the TPS65982 which may be setting a low level.
    Besides, in the EVM, SDA signal is wrong wired.

    To only control TUSB546-DCI you will need to remove connection from TUSB546-DCI to TPS65982 and connect the aardvark to the right I2C pins from TUSB546-DCI. This will require removing of some components and extra wiring. Finally there won;t be communication between TUSB546-DCI and TPS65982.

    We can have a call to discuss it.

    Regards
  • 0 in reply to Moises Garcia
    TI__Prodigy 50 points

    Hi Moises,

       Thanks for the help.

    You said that the SDA line is wrongly wired in the EVM.

    • By this,you mean that the SDA line from the TPS65982 to the TUSB546 is wrongly wired, isn't it?
    • If that is so, this means with the current EVM , there is no way to talk to the TUSB546 via I2C from TPS65982 , right ? Because if  I have understood correctly, when we set the I2C_EN to high in the EVM, we allow the conversation b/w the TUSB546 and TPS65982 to happen via I2C. Now if the wiring is faulty, this communication wouldn't happen, right?
    • Also, given the faulty wiring in the current EVM, do we have a new revision of the hardware in the market with the issue resolved?

    Thanks

    Abhijit

  • 0 in reply to Abhijit Ray
    TI__Mastermind 23815 points
    Hi Abhijit,

    SDA is connected to the wrong pin in TUSB546-DCI, this EVM and the firmware for TPS65982 was designed for GPIO control not for I2C.
    There is no way that TPS65982 can talk to TUSB546-DCI because the TUSB546-DCI's firmware is not intended to do it, this is why the wrong connection wasn't detected.
    There is no revision of hardware because the board and the firmware are intended for GPIO control.

    Regards