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ucd3138

michael
Prodigy 170 points
Other Parts Discussed in Thread: UCD3138

请问ucd3138有内部上拉或者下拉电阻吗？

  • 0
    TI__Expert 4970 points

    Zheng,

    We do not use passive pull-up or pull-down resistors. Instead, we use active totem pole transistors to pull up or down the pins. Does this answer your question?

    Regards,

    Brandon Vonk

  • 0 in reply to Brandon Vonk
    Prodigy 170 points

    Brandon,

    Thanks for your reply.

    Actually, I want to use a GPIO(ucd3138) as input, when it is opened, I hope its level is fixed(high or low is ok). So, is this function configurable?

  • 0 in reply to michael
    TI__Expert 4970 points

    Zheng,

    Yes. Take a look at the rightmost column of the table shown on pages 10, 11, and 14 of the UCD3138 datasheet. For the 64-pin version, almost half of the pins are configurable as GPIO input/output configurable. The same goes for the 40-pin package.

    I hope this answers your question. Please let me know if you have any others. Thanks!

    Regards,

    Brandon Vonk

  • 0 in reply to Brandon Vonk
    TI__Genius 17090 points

    The DPWM pins are reset to be outputs pulling low.  Pretty much all the other GPIO pins come up as high impedance inputs, which should be fine for your purposes.  If you are going to use them as outputs, you may want to put pull up or pull down resistors on them to hold them in the desired position until the firmware comes around and configures them. 

    Happy Debugging,

    Ian Bower

  • 0 in reply to Ian Bower
    Prodigy 170 points

    If I configure one GPIO as input, and leave it open, then I want to know the logic level is high or low when reading it?

    And, I see open drain or push-pull from document as below:

         

    Is there a internal functional diagram about the GPIO?

    Best Regards

  • 0 in reply to michael
    TI__Expert 4970 points

    The GPIOs are in a state of high impedance when configured as INPUTs. They will float if they are not pulled high or low.