• So you're connecting 12v to an input pin via a 10k resistor? I'd expect that to maybe cause issues, yes.

    Basically 10v drop at 10k is 1mA going in to the chip, but the chip itself draws way less than that when idle. While it's caught by the chips diodes, it means that it is powering the 3.3v supply via an IO pin. I reckon if you look at the 3.3v pins you'll find that the voltage is well above 3v

    I would add a permanent resistor to pull down, so that the voltage always stays in the 3.3v range - otherwise it might cause damage to the chip.

  • Not quite.
    The 12V pulls the pin high, but the (external) diode shortens that to 3,3V.
    I just measured the voltage to be about 3.8V on the pin.
    Do you think this is still an issue?

    For pulldown (in case of power loss) I used the internal resistor via pinMode()

    As with the flickering this may have been cause by wrongly wired MOSFETs or a shortage between 3,3V and 5V PIN.
    Prototyping got a bit messy lately... ;-)


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