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Beagle Bone board using the AM3358 processor

Douglas Macauley
Prodigy 70 points
Other Parts Discussed in Thread: AM3358

Does the AM3358 have a way to configure an open-drain GPIO?

  • 0
    Prodigy 70 points

    If not, where is the information about the I/O cell options for each GPIO part? For example, I/O structure such as push-pull, etc?

  • 0 in reply to Douglas Macauley
    TI__Guru* 90025 points

    Doug,

    you can have a GPIO function as a pseudo open drain by setting up the GPIO DATAOUT register bit = 0, then use the OE register to drive a zero (set OUTPUTEN=0) or turn it into an input (set OUTPUTEN=1).  In the pinmux register for the IO, ensure the RX enable bit is enabled, and no pulls are enabled (just rely on the board pullup).  

    Regards,

    James

  • 0 in reply to JJD
    Prodigy 70 points

    Hi James,

    Thank you. If I understand correctly, you are saying to control the output enable by turning it off to act as an open drain pin when not using it?

    Douglas

  • +1 in reply to Douglas Macauley
    TI__Guru* 90025 points

    Yes, turning off the output enable will disable its output driver and turn it into an input only pin.  This will allow an external source (pull up or other open drain output) to control the signal.  Of course, care must be taken to ensure there is no contention on the signal if there is something other than the pull up controlling it.

    Regards,

    James