I posted on the GitHub site but I realize it should have probably gone here:
I have a prototype that I built with a standard Arduino and I’m trying to adapt it to Controllino. The devices I am interfacing with signal LOW, so unifying the supply ground for my Arduino and the device allows me to use INPUT_PULLUP on the input pins to use Arduino’s internal pullup resistors. Then I simply read the LOW signal directly. If what I see is correct the Controllino has an internal PULLDOWN resistor, that prevents the use of INPUT_PULLUP which is unfortunate because that would then require an additional external relay to basically change the LOW signals into HIGH signals. Am I missing something or is there another way to gather LOW signals directly?
Yes the screw terminal Inputs are all forced to ground by the voltage divider.
If you need a screw terminal input to be pulled up … you can us an external pullup resistor … 10k for example.
If you need a 5V pin … I would recommend to use one of the not used communication pins like I2C, RX/TX 2, /SS, … or also the digital outputs D0, D1, Dx (of course the screw output will then switch accordingly, but if you don’t use it, it does not matter) … these pins are not tied to GND and you can use the internal Pullup.