//calculatesthe angle based on a rotary encoder for teaching purposes
//includes rotary encoder and interrupts HTL Anichstraße

// encoder pins
#define ENCODER_CLK 2 //pin usabele for interrupts
#define ENCODER_DT  4 
#define ENCODER_SW 3 //pin usabele for interrupts
// max enconder steps for one rotation based on the wiki of wokwi
#define ROTARY_MAX 20
//variable to save the actual count / position of the encoder
//the actual position of the decoder at startup is definded as 0 deg.
int counter = 0;
//variable to save the old counter value
int prevCounter = counter;


void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, I'm the encoder king!");

  // Initialize encoder pins
  pinMode(ENCODER_CLK, INPUT); 
  pinMode(ENCODER_DT, INPUT);
  pinMode(ENCODER_SW, INPUT_PULLUP);
  //attach interupt for the detection of encoder changes
  attachInterrupt(digitalPinToInterrupt(ENCODER_CLK), readEncoder, FALLING);
  //attach interupt for reset the 0 deg. postion
  attachInterrupt(digitalPinToInterrupt(ENCODER_SW), resetCounter, FALLING);
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

// method to read the encoder (called by interrupt)
void readEncoder() {
  int dtValue = digitalRead(ENCODER_DT);
  if (dtValue == HIGH) {
    counter++; // Clockwise
  }
  if (dtValue == LOW) { //Counterclockwise
    if (counter != 0){
      counter--; //decreases the counter
    }else {
      // avoid to get negative angles if the last counter value
      // was zero (0 deg.)
      counter = ROTARY_MAX -1; 
    }
    
  }
  
  //resets the counter to zero if an 360 deg rotation occured
  if (counter == ROTARY_MAX){
    counter = 0;
  }
  Serial.println("Actual counter: "+ String(counter));
}

// resets the counter (called by interrupt)
//if the decoder is pressed this sets the angle to 0 deg. at the actual position
void resetCounter() {
  //Deactivate the interrupts to prevent the reset of the counter 
  //from being interrupted by turning the encoder.
  noInterrupts();
  counter = 0;
  Serial.println("Reset to 0 deg.");
  interrupts();
}


void loop() {
  delay(10); //only for wokwi simulation
  //calculate the angle of the encoder based on the actual counter
  int angle = abs((360/ROTARY_MAX)*counter);
  //print the angle only when changed
  if (prevCounter != counter) {
    Serial.println("Actual angle: "+ String(angle));
  }
  prevCounter = counter;


}