Problem with Handling 7 Encoders with interrupts on Arduino Every

Hey Together,

I started a Project where I need to read in 7 Digital Encoders, each with 2 Channels (Differential).
I found the Arduino Nano Every and was quite thrilled that all Digital Pins are capable of Interrupts. [attachInterrupt() - Arduino-Referenz]

I built up a the prototype using LM393n Comparators for the differential Signal and Pull-Up's to Vcc to get "0V" or roundabout "5V" from each channel(Arduino input threshold supposedly is 3.5V so we should be golden on this front). I tested every Channel with my picoscope and it seems to work like a charm. Basic sketch of each channel in appendix

From a Sofware point of view this principle works also well on the native "Digital-Only Pins" (D2-D12). Here I get my interrupts while moving my encoders, and the system is quite when not.
It does not work on "Analog and Digital Pins" (D14-D17). Here interrupt is constantly triggered. Even when I pull the Pin down to GND. If I disable the Pin 19 the same problem occurs on pin 20. I think I simply don't grasp how to use the Pins properly. But I also can't find a good fix.
I tried to use the "MegaCoreX-Lib" and use those Analog inputs as comparators themselves. But no luck there. It just trows out more issues. (Also it's quite unpretty to look at codewise)

I Put my code last coz It's probably just caused by my wrong understanding of the pins. I put a snippit here. Code is the same for all Pins.

pinMode(19, INPUT);
attachInterrupt(digitalPinToInterrupt(19), interruptFunction, Change);

//Other Stuff

void interruptFunction(){

so I hope this Post contains anything thats needed. I am happy to provide more Info if needed.

thanks for your time and help!



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Digital encoders have two outputs that are not differential but 90º out of phase, so the outputs perform a grey code count as the shaft is turned -- 00 01 11 10 00 ... in one direction and 00 10 11 01 00 in the other. So you don't want to use a comparator but bring both both outputs to digital pins. Then you can have each one cause an interrupt on change. In fact they can both share a single interrupt service routine since only one changes value at a time:

volatile int position;
void interruptFunction(void) {
  // phase A or phase B has changed, but we don't know which!
  static bool lastPhaseA, lastPhaseB;
  bool a = digitalRead(phaseAPin);
  bool b = digitalRead(phaseBPin);
  if (lastPhaseA != a) {
    position += (a == b) ? -1 : 1;
    lastPhaseA = a;
  if (lastPhaseB != b) {
    position += (a == b) ? 1 : -1;
    lastPhaseB = b;

Isn’t Change supposed to be CHANGE? It’s an enum and C/C++ is case sensitive

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