/*Whistling sound switch; author: ELECTRONOOBS 
 * Subscribe: http://www.youtube.com/c/ELECTRONOOBS
 * 
 * Activate any Arduino loop just by whistling. The circuit is very easy.
 * Check the entire tutorial here: http://www.electronoobs.com/eng_arduino_tut19.php * 
 * 
 * Input pin is D8
 * Relay output is D13
 * PWM buzzer output is D3
*/

//We create a variable for the time width value of the input signal
unsigned long last_pulse_time_counter, present_time;
//We create 1 variables to store the previous value of the input signal (if LOW or HIGH)
byte last_PIN_state;
//To store the final width value we create this variables (this will be half of the period)
   

//Variables
float Period = 0;
float Frequency_micro = 0;
float Frequency = 0;
int Pulse_amount = 0;
int pulse_is_measured = 0;
int sum_count = 0;                    //Increaase the count amount by one in each loop only if the range is correct
float freq_sum = 0; 
float freq_mean = 0;



void setup() {
  /*
   * Port registers allow for lower-level and faster manipulation of the i/o pins of the microcontroller on an Arduino board. 
   * The chips used on the Arduino board (the ATmega8 and ATmega168) have three ports:
     -B (digital pin 8 to 13)
     -C (analog input pins)
     -D (digital pins 0 to 7)   
  //All Arduino (Atmega) digital pins are inputs when you begin...
  */     
  PCICR |= (1 << PCIE0);    //enable PCMSK0 scan                                                 
  PCMSK0 |= (1 << PCINT0);  //Set pin "D8" trigger an interrupt on "any" state change.                                          

  
  
  //Start the serial in order to see the result on the monitor
  //Remember to select the same baud rate on the serial monitor
  Serial.begin(250000);  

}

void loop() {
  /* Ok, so in the loop the only thing that we do in this example is to print
   * the received values on the Serial monitor. The PWM values are read in the ISR below.
   */ 

   if(pulse_is_measured)                          //Only when a full pulse is measured we enter the loop
   {
     pulse_is_measured = 0;                       //We reset "the pulse is detected" for the next loop
     Frequency_micro = 1/Period;                  //Invert the period and get the frequency (in Hertz by us)
     Frequency = Frequency_micro*1000000;         //Multiply by one million and get frequency (in Hertz by seconds)

      sum_count = sum_count+1;                    //Increaase the count amount by one in each loop only if the range is correct
      freq_sum = freq_sum + Frequency;            //calculating a mean
      freq_mean = freq_sum/sum_count;

      if(sum_count >= 200)                        //I want 200 detected pulses with the same frequency range in a raw to 
      {                                           //be detected before I give the mean. 
        Serial.print("Freq: ");                   //Print the values
        Serial.println(freq_mean);        
        sum_count=0;                              //Reset the values
        freq_mean = 0;
        freq_sum = 0;
        
      }
   }//end of if pulse is measured
}//end of loop




//This is the pulse width interruption routine
//----------------------------------------------

ISR(PCINT0_vect){
//First we take the present_time value in micro seconds using the micros() function
  
  present_time = micros();
  ///////////////////////////////////////Signal input
  if(PINB & B00000001){                                     //We make an AND with the pin state register, We verify if pin 8 is HIGH???
    if(last_PIN_state == 0){                                //If the last state was 0, then we have a state change...
      last_PIN_state = 1;                                   //Store the current state into the last state for the next loop
      Period = present_time - last_pulse_time_counter; //We make the time difference. Channel 1 is current_time - timer_1.
      last_pulse_time_counter = present_time;               //Set pulse_time_counter to current value.
      pulse_is_measured = 1;                                //We indicate that one full width was measured
    }
  }
  else if(last_PIN_state == 1){                             //If pin 8 is LOW and the last state was HIGH then we have a state change      
    last_PIN_state = 0;                                     //Store the current state into the last state for the next loop                                    
  }



  
 
}