// Definition of the constants
#define SW_ENCODER 13
#define DT_ENCODER 12
#define CLK_ENCODER 11

// Definition of global variables
int counter_encoder = 0;

void analyse_encoder ()
{
  // Definition of static variables
  static bool clkState;
  static bool clkLastState = true;  
  // Reads the state of the clk input
  clkState = digitalRead(CLK_ENCODER);
  // Check if the previous and the current state of the clk input are different
  if (clkState == false and clkLastState == true)
  {     
    // Check if the dt input state is different to the clk input state (encoder is rotating clockwise)
    if (digitalRead(DT_ENCODER) != clkState) 
    { 
      counter_encoder ++;
    } 
    else 
    {
      counter_encoder --;
    }
  } 
  // Updates the previous state of the clk input with the current state
  clkLastState = clkState;
}


// Setup of the programme: Is executed once during the start of the microcontroller
void setup() 
{
  // Initialising serial communication
  Serial.begin(9600);
  // Defining the encoder pins as pullup inputs
  pinMode(SW_ENCODER, INPUT_PULLUP);
  pinMode(DT_ENCODER, INPUT_PULLUP);
  pinMode(CLK_ENCODER, INPUT_PULLUP);

}

void loop() 
{
  analyse_encoder();
  Serial.print(counter_encoder);
}