//https://forum.arduino.cc/t/optical-encoder-skips-pulses-at-high-speeds/1275203/1
#define encoderPinA 2
#define encoderPinB 3
volatile long encoderCount = 0;
//-------------------------------------------------------------
void setup() {
  Serial.begin(115200);
  pinMode(encoderPinA, INPUT_PULLUP);
  pinMode(encoderPinB, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(encoderPinA), handleEncoder, RISING);
  // attachInterrupt(digitalPinToInterrupt(encoderPinB),handleEncoder2, RISING);
}
//-------------------------------------------------------------
void loop() {
  if ((encoderCount % 1000) == 0 )  {
    Serial.println(encoderCount);
  }
}
//-------------------------------------------------------------
void handleEncoder() {
  if (digitalRead(encoderPinA) > digitalRead(encoderPinB)) {
    encoderCount++;
  }
  else {
    encoderCount--;
  }
}