Encoder + Bounce2 Library

Question

I am working towards debouncing my keyes rotary encoder using the Bounce2 library found here ( https://github.com/thomasfredericks/Bounce2 ).

I believe the problem lies in my code as there isn't much in terms of a circuit. The encoder is connected to my arduino as follows

• 5V : connected to 5v out on arduino
• GND : connected to GND
• SW : connected to pin A1
• DT : connected to pin 3
• CLK : connected to pin 2

I am trying to call an ISR from a CLK input. When the ISR is called it should increment or decrement a value based on the direction the encoder was turned. This encoder is tied to an ISR because it will be used for user input and I would like it to remain responsive throughout the sketch.

Previously, I was using millis() to debounce the encoder, but I was still having trouble receiving more than one input from the encoder. I was hoping that this libary would resolve this issue.

The current output of the code I have included never increments/decrements the starting value no matter which direction the encoder is turned. In short, it always outputs 0.

If someone could explain what I am doing wrong that would be wonderful! Then maybe, but just maybe, I can stop beating my head against my desk. :p

Thanks, Kevin

#include <Bounce2.h>

#define sw A1
#define LED_PIN 9
#define clk 2
#define dt 3

int ledState = LOW;
int onOff = LOW;

volatile int virtualPosition = 0;
int lastCount = 0;


// Initiate bounce objects
Bounce debouncerSW = Bounce();
Bounce debouncerROT = Bounce();

void setup() {
  Serial.begin(115200);

  pinMode(sw, INPUT_PULLUP);
  pinMode(clk, INPUT);
  pinMode(dt, INPUT);
  pinMode(LED_PIN, OUTPUT);

  // set up button instace
  debouncerSW.attach(sw);
  debouncerSW.interval(100);

  // set up rotary encoder instance
  debouncerROT.attach(clk);
  debouncerROT.interval(10);

  // setup the LED
  digitalWrite(LED_PIN, ledState);

  // attach ISR
  attachInterrupt(digitalPinToInterrupt(clk), isr, LOW);

  Serial.println("Start"); // just to let me know sketch has finished setup
}

void loop() {

  debouncerSW.update();

  if ( debouncerSW.fell() ) {
    ledState = !ledState;
    onOff = !onOff;
    digitalWrite(LED_PIN, ledState);

    //read-outs
    Serial.print("onOff = ");
    Serial.println(onOff);
  }
  virtualPosition = lastCount;

  //read-outs
  Serial.print ("lastCount = ");
  Serial.println (lastCount);

  delay(1000); // for readability / simulates delay time for rest of main sketch
} // end main loop

void isr ()  {

  // Update the Bounce instance :
  debouncerROT.update();

  if (debouncerROT.fell()) {
    if (digitalRead(dt) == LOW)
    {
      virtualPosition -- ; // Could be -5 or -10
    }
    else {
      virtualPosition ++ ; // Could be +5 or +10
    }

    // Restrict value from 0 to 100
    virtualPosition = min(100, max(0, virtualPosition));
  }
} // end ISR