#define FRONT_RISENOT
#define DEBUG //NOT

#define LED 7
#define INT0_PIN 2
#define MAX_FRONTS_AMO 100
#define MAX_MCS_FROM_LAST_FRONT 50000 // 50 милисекунд с последнего фронта
#define ON_OFF_KEY_CODE 1692


volatile boolean ON_OFF = false;
volatile unsigned long mcs_from_last_front = 0;
volatile unsigned long mcs[MAX_FRONTS_AMO] = {0};
volatile unsigned fronts_amo = 0;


void int0_routine()
{
  if(fronts_amo >= MAX_FRONTS_AMO) 
    return;  
  mcs_from_last_front = micros();  
  mcs[fronts_amo] = mcs_from_last_front;
  fronts_amo++;
}


void setup() 
{
  #ifdef DEBUG
  Serial.begin(9600);
  #endif
  pinMode(LED, OUTPUT);
  pinMode(INT0_PIN, INPUT_PULLUP);
  digitalWrite(LED, ON_OFF);
  #ifdef FRONT_RISE
  attachInterrupt(0, int0_routine, RISING);
  #else
  attachInterrupt(0, int0_routine, CHANGE);
  #endif
}


void loop() 
{
  if (fronts_amo < 2) 
    return;
  
  if (micros() > (mcs_from_last_front + MAX_MCS_FROM_LAST_FRONT))
  {
    uint16_t hash = 0;
    for(int i = 0; i < fronts_amo - 1; i++)
    {
      uint16_t time_tween_fronts = mcs[i+1] - mcs[i];
      
      #ifdef DEBUG
      Serial.println(time_tween_fronts, DEC);
      #endif

      time_tween_fronts /= 700;
      hash += (1 << i) * time_tween_fronts;
    }
    
    #ifdef DEBUG
    Serial.print("---- changes: ");
    Serial.print(fronts_amo, DEC);
    Serial.print("---- hash: ");
    Serial.println(hash, DEC);
    #endif
    
    if (hash == ON_OFF_KEY_CODE)
      digitalWrite(LED, ON_OFF = !ON_OFF);

    fronts_amo = 0;
  }
}