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In the datasheet of this MCU, on page 37, it says:

Note: To guarantee the XOSC32K behavior in crystal mode, PC00 must be static.

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I use pin 1 (PA00) as a clock oscillator input.

My questions:

  1. What is the meaning of static? What does "PC00 must be static" mean?

  2. Is it OK with respect to the above NOTE point?

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  1. I assume they mean that PC00 should never switch between high and low, as this might couple noise into the adjacent clock pins. It should be static at always high or always low.

  2. If you use a clock oscillator instead of crystal, I don't think this should be an issue as the sensitive part is hidden within the oscillator.

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  • \$\begingroup\$ Thank you for the answer. I've connected the PC00 pin to a voltage divider with 3V. Hope its OK \$\endgroup\$
    – user220456
    Commented Oct 11, 2022 at 8:14
  • \$\begingroup\$ PC00 is one of the clock pins. It seems weird that setting the crystal register doesnt disable the pin, In looked for errata and couldnt find any relating to this \$\endgroup\$
    – Anas Malas
    Commented Oct 11, 2022 at 8:14
  • \$\begingroup\$ @Newbie if you want to use XOSC32K, that's a bad idea. If you dont want to use it, it doesnt matter what you do with PC00 \$\endgroup\$
    – Anas Malas
    Commented Oct 11, 2022 at 8:15
  • \$\begingroup\$ @AnasMalas, I've connected PA00. Clock oscillator output is connected to PA00 input. PC00 is connected a voltage divided. Is it OK? Why you say its a bad idea? \$\endgroup\$
    – user220456
    Commented Oct 11, 2022 at 8:19
  • \$\begingroup\$ You don't say if PC00 is an input or output and what you do with it. \$\endgroup\$
    – Justme
    Commented Oct 11, 2022 at 8:25

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