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UCD90160A: GPI Pin Question

PY (Pengyu) Song
Expert 5860 points
Part Number: UCD90160A

Hi team,

Regarding GPI polarity, say when it is configured as "Active Low", according to datasheet, it is referring to "output voltage level"? What does it really mean and what UCD does internally? 

When configured as “Active Low”, is it ok to pull it down using a 1K resistor (for input = '0') and pull it up using 3.3V without any resistor (for input = '1')? 

Thanks. 

  • 0
    TI__Guru 58080 points
    Hi Pengyu

    Please refer section 6.5 Electrical Characteristics at the Data sheet for the Digital Input definitiaon.
    When the GPI is configured as ACTIVE Low, UCD will treat the GPI as ASSERTED if the input is logic low, other wise it is de-asserted.
    When the GPI is configured as ACTIVE HIGH, UCD will treat the GPI as ASSERTED if the input is logic high, other wise it is de-asserted.

    When the GPI is asserted, if the GPI is used for sequencing turn on dependencies, UCD will treat the dependencies is met.
    When the GPI is de-asserted, if the GPI is used for sequencing turn off dependenceis, UCD will treat the dependencies is met.
    Please refer section 4.2 of www.ti.com/.../slua815.pdf

    The GPI is mainly from external system, it is up to custome how to use the pull-up and pull-down, but we always recommend to have a reseistor

    What do you try to achieve here?

    Regards

    Yihe
  • 0 in reply to yihe
    TI__Expert 5860 points

    Dear Yihe,

    Your answer is clear but I'm still confused regarding below description, which seems not relevant to GPI polarity according to your explanation?  Thanks. 

  • 0 in reply to PY (Pengyu) Song
    TI__Guru 58080 points

    Hi Pengyu

    The description is for the GPO not for GPI. We will correct this in the new GUI.

    thanks

    Yihe