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TMDS181: TX_TERM_CTL function

Kawai
Guru 19785 points
Part Number: TMDS181

Hi Team,

Please allow me to ask you about the TX_TERM_CTL function.

When TMDS181 used in Pin mode and TX_TERM_CTL pin set to floating, TX termination resistor will be chosen automatically.

However, when used in I2C mode, I believe REG 0x0B [4:3] will have the priority than the pin setting that automatic TX termination resistor control can not be used.

Above is my understanding.

Regarding the data sheet page 46, I found below description.

Above is explaining the "I2C control" for HDMI2.0a and HDMI 1.4b.

[Question]
What does "TX_TERM_CTL = NC for Auto Select" here mean?

I believe user would always need to program REG 0x0B [4:3] when used in I2C mode.

Best Regards,

Kawai

  • 0
    TI__Guru 64326 points
    Kawai,

    To clarify, when TMDS181 is used in I2C mode the REG 0x0B must be written to control termination, there is no Auto mode in I2C mode. If in Pin Strap Mode you can read REG 0x0B for termination state determined by Auto Select and writes will be ignored.
  • 0 in reply to Malik Barton57
    Guru 19785 points
    Hi Malik-san,

    Thanks for the explanation. It seems my understanding was correct.

    The description in page 46, "TX_TERM_CTL = NC for Auto Select" is confusing.

    I think it is better to be deleted in the next data sheet update.

    Best Regards,
    Kawai