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TM4C123GH6PM: Startup Conditions of GPIOs

Jared Becker
Genius 11945 points

Part Number: TM4C123GH6PM

Hi Team,

Can you please help me understand what the startup conditions of the GPIO pins are for the TM4C123? Are they tristated, floating, or are they tied high or low on startup? 

Thank you in advance for your help.

Best,

Jared

  • 0
    TI__Guru**** 191886 points
    Hi Jared,
    Most GPIO pins are configured as GPIOs and tri-stated by default. However, there are a few pins which may be programmed to a non-GPIO function.
  • 0
    Guru 117855 points

    When in such (fair) doubt - does not "RTFM" rise to, "top of the list?"

    Section 10 of the MCU Manual further details - there are individual registers which control/enable pull-up or pull-down - my quick read of "GPIOPUR" noted these as "0" at reset thus not pulled up ..   The corresponding "GPIOPDR" lists values as "0" post Reset again pull-down R's are NOT enabled.   It thus appears that "unprogrammed GPIOs" float (never good - but for brief periods) and await software to configure...

    As Charles notes - there are multiple GPIO pins which fall under, "Special Considerations" and may be "Re-Purposed" from GPIO to Alternate Functions.