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AMacd.1
Senior
March 15, 2022
Question

On the STM8L101F1U, some IO port register bits do not have actual pins on the package. How should these register bits be initialized? Should I set them to input pullup, output or just input floating? Note: Part does NOT have COMP_REF.

  • March 15, 2022
  • 3 replies
  • 919 views

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    3 replies

    S.Ma
    Principal
    March 16, 2022

    As long as the io is not floating, the main difference might be small consumption change between say open drain low and push pull high, in low power mode.

    AMacd.1
    AMacd.1Author
    Senior
    March 16, 2022

    How do I know whether IO that don't appear at external pins, such as PA4-7, PC5-7, and PD1-7 are floating or not?

    AMacd.1
    AMacd.1Author
    Senior
    March 16, 2022

    Maybe this is just a case of TL;DR on my part; Going back to the user guide, I find this: "Warning: On some packages, some ports must be considered as active even if they do not exist on the package. To avoid spurious effects, configure them as pullup-inputs without interrupt at startup , and keep them in this state when changing the port configuration. Refer to the datasheet for additional information."

    I guess I can assume that this warning applies to the part in question (STM8L101F1U) but the existence of a similar warning in the data sheet that applies only to the COMP_REF part STM8L101F1U6A) has thrown me off a bit. Why would the data sheet apply this warning only to the COMP_REF parts?