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TMDS181: TX Termination settings

Kawai
Guru 19775 points
Part Number: TMDS181

Hi Team,

Please allow me to clarify the settings and the operation of TX termination control using TMDS181.

Q1). Does the device automatically choose the TX termination resistor as shown in the TX_TERM_CTL pin settings, when setting the pins in the following condition ?

- Pin10: I2C_EN/PIN = High  (I2C Enable)
- Pin26: TX_TERM_CTL = NC (Floating is Automatic Select Mode)

Customer does not see the device operating in "automatic select mode" using the EVM.

Q2).  Customer set the TX_TERM_CTL register through EyeScan Tool, however, TX termination resistor did not change. Is there any override bit for this register setting to work prior to the pin setting ?

Please also advise us which asked in the following post.

https://e2e.ti.com/support/interface/digital_interface/f/130/t/588766

Since customer is in a hurry, it would be helpful if you could give us your comments by 4/17 (PST).

Thanks in advance.

Best Regards,

Kawai

  • 0
    TI__Mastermind 23815 points

    Hi Kawai-san,

    When I2C_EN=HIGH, the device operates in I2C mode, control pins are ignored.

    I I2C mode, there is no automatic Tx termination selection

    To change Tx termination by I2C, you have to select the desired termination in register 0x0B[4:3], the, assert APPLY_RXTX_CHANGE, register 0x0A[2]

    When I2C_EN=LOW, the device is in pin strap mode, I2C registers will reflect the status of control pins.

    Regards

  • 0 in reply to Moises Garcia
    Guru 19775 points
    Hi Moises-san,

    Thank you for the information.

    Best Regards,
    Kawai