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XIO2001: Unused GPIO pins

Oba
Genius 15750 points
Part Number: XIO2001

Hello,

I would like to confirm how to terminate GPIO0//CLKRUN, GPIO1 //PWR_OVRD, GPIO2, GPIO3//SDA, GPIO4 //SCL pins if these are unused.
Is it OK to leave unconnected for all these pins?

Regards,
Oba

  • 0
    TI__Mastermind 35130 points

    Hi Oba,

    GPIO0 and GPIO4 should be connected to ground with an external resistor if unused. I believe the others are fine to leave unconnected.

    Regards,

    I.K.

  • 0 in reply to Ikechukwu Anyiam
    TI__Genius 15750 points

    Hello I.K,

     

    Thanks for your reply.

     

    I read the datasheet a little bit more.

     

    Regarding GPIO0, it has internal pullup and it will be active if CLKRUN is disabled by CLKRUN_EN pin =0.

    Why is external pull-down required for GPIO0?

    Even if it is configured as CLKRUN, the datasheet says that external pull-up is required, not pull-down.

     

    Regarding GPIO4, I understand external pull-down is required to avoid to be configured serial-bus mode for GPIO3/4.

    But I have one additional question. The datasheet says that GPIO0,1,2 and 4 have internal pull-up if they are configured as GPIO.

    But GPIO3 seems not to have internal pull-up or down (Page 14 of the datasheet).

    Is it really correct?

    If it really doesn’t have internal pull-up/down, it means GPIO3 pin is required external pull-down or up.

     

    Regards,

    Oba

  • 0 in reply to Oba
    TI__Mastermind 35130 points

    Hi Oba,

    My mistake, it is CLKRUN_EN that requires an external pulldown if it is unused. Some of these pins have internal pulldowns that are not activated, so external pulldowns are required.This is the case for CLKRUN_EN, EXT_ARB_EN, and GPIO4. It should be okay to leave GPIO0 itself floating though.

    You can put a pulldown on GPIO3 but I don't think it really matters as the function of this pin depends on whether or not an pullup is detected on SCL.

    Regards,

    I.K.

  • 0 in reply to Ikechukwu Anyiam
    TI__Genius 15750 points

    Hi I.K.

    Regarding GPIO3, could you please confirm whether this pin doesn't really have internal pull-up or down like other GPIOs?
    I wonder why the datasheet says only this GPIO3 pin doesn't have internal pull-up like other GPIOs.
    If this pin is configured as GPIO3 and this pin doesn't have internal pull-up or down, external pull-up or down should be required because usually digital input can't be floating.

    Regards,
    Oba

  • 0 in reply to Oba
    TI__Mastermind 35130 points

    Hi Oba,

    I looked at this in the lab on our EVM and it looks like GPIO3 has an internal pull-up. 

    Regards,

    I.K.