framework-arduinoteensy-cxx20/libraries/QuadEncoder/examples/SimpleEncoder/SimpleEncoder.ino

/* Teensy 4 H/S Encoder Library - TwoKnobs Example
 * http://www.pjrc.com/teensy/td_libs_Encoder.html
 *
 * This example code is in the public domain.
 */

#include "QuadEncoder.h"

// Change these pin numbers to the pins connected to your encoder.
// Allowable encoder pins:
// 0, 1, 2, 3, 4, 5, 7, 30, 31 and 33
// Encoder on channel 1 of 4 available
// Phase A (pin0), PhaseB(pin1), 
QuadEncoder knobLeft(1, 0, 1);
// Encoder on channel 2 of 4 available
//Phase A (pin2), PhaseB(pin3), Pullups Req(0)
QuadEncoder knobRight(2, 2, 3);
//   avoid using pins with LEDs attached

void setup() {
  Serial.begin(9600);
  Serial.println("TwoKnobs Encoder Test:");
  /* Initialize Encoder/knobLeft. */
  knobLeft.setInitConfig();
  knobLeft.init();
  /* Initialize Encoder/knobRight. */
  knobRight.setInitConfig();
  knobRight.init();
}

long positionLeft  = -999;
long positionRight = -999;

void loop() {
  long newLeft, newRight;
  newLeft = knobLeft.read();
  newRight = knobRight.read();
  if (newLeft != positionLeft || newRight != positionRight) {
    Serial.print("Left = ");
    Serial.print(newLeft);
    Serial.print(", Right = ");
    Serial.print(newRight);
    Serial.println();
    positionLeft = newLeft;
    positionRight = newRight;
  }
  // if a character is sent from the serial monitor,
  // reset both back to zero.
  if (Serial.available()) {
    Serial.read();
    Serial.println("Reset both knobs to zero");
    knobLeft.write(0);
    knobRight.write(0);
  }
}