• At the 90 degree rotation mark I have a readout of 180 degrees.
• At the 180 degree rotation mark I have a readout of 0 because the code has it reset to zero after 359 degrees.
• At the 270 degree rotation mark I have a readout of 180 degrees.
• At the 0 degree mark it is zero again and that's what I would expect from the index. If I restart the Arduino Mega at the 270 degree mark, the index resets itself to zero like it should. Being new to this, before I had the index working it was working correctly minus the index function, now it seems to be double counting. Any ideas? // Wiring connections for my encoder: // Brown : VCC = 5V // Blue + Shield : 0V = GND // Black : ENCODER0PINA, Pin 20 // White : ENCODER0PINB, Pin 17 // Orange : ENCODER0PINI, Pin 19

#define ENCODER0PINA 20 // this pin needs to support interrupts #define ENCODER0PINB 17 // no interrupt required #define ENCODER0PINI 19 // this pin needs to support interrupts

// variables modified by interrupt handler must be declared as volatile volatile long encoder0Position = 0; volatile long interruptsReceived = 0; volatile byte INTFLAG1 = 0;

// track last position so we know whether it's worth printing new output long previousPosition = 0;

void setup() {

// inputs pinMode(ENCODER0PINA, INPUT); digitalWrite(ENCODER0PINA, HIGH); // turn on pullup resistor pinMode(ENCODER0PINB, INPUT); digitalWrite(ENCODER0PINB, HIGH); // turn on pullup resistor pinMode(ENCODER0PINI, INPUT); digitalWrite(ENCODER0PINI, HIGH); // turn on pullup resistor

// interrupts attachInterrupt(3, onInterrupt, CHANGE); // encoder track A on interrupt 3 - pin 20 attachInterrupt(4, onReset, CHANGE); // encoder Index track on interrupt 4 - pin 19

// enable diagnostic output Serial.begin (115200); Serial.println("Ready."); }

void loop() { // only display position info if has changed if (encoder0Position != previousPosition ) { Serial.println(encoder0Position, DEC);

previousPosition = encoder0Position;

} }

// interrupt function needs to do as little as possible

void onReset() { // read Index input int i = digitalRead(ENCODER0PINI); if (i == 1) { encoder0Position = INTFLAG1; } }

void onInterrupt() { // read both directional inputs int a = digitalRead(ENCODER0PINA); int b = digitalRead(ENCODER0PINB);

if (a == b) { // b is leading a (counter-clockwise) encoder0Position--; if (encoder0Position < 0) { encoder0Position = (encoder0Position + 360); } } else { // a is leading b (clockwise) encoder0Position++; if (encoder0Position >= 360) { encoder0Position = (encoder0Position - 360); } } }

• At the 90 degree rotation mark I have a readout of 180 degrees.

• At the 180 degree rotation mark I have a readout of 0 because the code has it reset to zero after 359 degrees.

• At the 270 degree rotation mark I have a readout of 180 degrees.

• At the 0 degree mark it is zero again and that's what I would expect from the index. If I restart the Arduino Mega at the 270 degree mark, the index resets itself to zero like it should. Being new to this, before I had the index working it was working correctly minus the index function, now it seems to be double counting. Any ideas?

  // Wiring connections for my encoder: // Brown : VCC = 5V // Blue + Shield : 0V = GND // Black : ENCODER0PINA, Pin 20 // White : ENCODER0PINB, Pin 17 // Orange : ENCODER0PINI, Pin 19

  #define ENCODER0PINA 20 // this pin needs to support interrupts #define ENCODER0PINB 17 // no interrupt required #define ENCODER0PINI 19 // this pin needs to support interrupts

  // variables modified by interrupt handler must be declared as volatile volatile long encoder0Position = 0; volatile long interruptsReceived = 0; volatile byte INTFLAG1 = 0;

  // track last position so we know whether it's worth printing new output long previousPosition = 0;

  void setup() {

  // inputs
  pinMode(ENCODER0PINA, INPUT);
  digitalWrite(ENCODER0PINA, HIGH);  // turn on pullup resistor
  pinMode(ENCODER0PINB, INPUT);
  digitalWrite(ENCODER0PINB, HIGH);  // turn on pullup resistor
  pinMode(ENCODER0PINI, INPUT);
  digitalWrite(ENCODER0PINI, HIGH);  // turn on pullup resistor
  
  // interrupts
  attachInterrupt(3, onInterrupt, CHANGE);  // encoder track A on interrupt 3 - pin 20
  attachInterrupt(4, onReset, CHANGE);  // encoder Index track on interrupt 4 - pin 19
  
  // enable diagnostic output
  Serial.begin (115200);
  Serial.println("Ready.");
  

  }

  void loop() { // only display position info if has changed if (encoder0Position != previousPosition ) { Serial.println(encoder0Position, DEC);

    previousPosition = encoder0Position;
  }
  

  }

  // interrupt function needs to do as little as possible

  void onReset() { // read Index input int i = digitalRead(ENCODER0PINI); if (i == 1) { encoder0Position = INTFLAG1; } }

  void onInterrupt() { // read both directional inputs int a = digitalRead(ENCODER0PINA); int b = digitalRead(ENCODER0PINB);

  if (a == b)
  {
    // b is leading a (counter-clockwise)
    encoder0Position--;
    if (encoder0Position < 0)
    {
      encoder0Position = (encoder0Position + 360);
    }
  }
  else
  {
    // a is leading b (clockwise)
    encoder0Position++;
    if (encoder0Position >= 360)
    {
      encoder0Position = (encoder0Position - 360);
    }
  }
  

  }