#include <LiquidCrystal.h>
//Assigning pins
int ledPin = 13;
int in_ir = 7; 
int motor = 6; 
int adc_input=A0;
LiquidCrystal lcd(8, 9, 10, 11, 12, 13); /// REGISTER SELECT PIN,ENABLE PIN,D4 PIN,D5 PIN, D6 PIN, D7 PIN

//variables
int timer1_counter;
unsigned int s=0;

unsigned int pwm_timing=0;
unsigned int pwm_duty=0;
unsigned int rpm_set=0;
unsigned int rpm_read=0;
char rpm_read_status = 0;
//timer

void setup()
{
  pinMode(ledPin,OUTPUT);
  pinMode(motor,OUTPUT);
  pinMode(in_ir,INPUT);
  pinMode(adc_input,INPUT);
  

  lcd.begin(16, 2);         // initializes the 16x2 LCD
  lcd.setCursor(2,0);       // sets the cursor at column 2 row 0
  lcd.print("IR TACHOMERTER  "); // prints temperature
  

  // initialize timer1 
  noInterrupts();           // disable all interrupts
  TCCR1A = 0;
  TCCR1B = 0;

  // Set timer1_counter to the correct value for our interrupt interval
  //timer1_counter = 64911;   // preload timer 65536-16MHz/256/100Hz
  //timer1_counter = 64286;   // preload timer 65536-16MHz/256/50Hz
  timer1_counter = 34286;   // preload timer 65536-16MHz/256/2Hz
  
  TCNT1 = timer1_counter;   // preload timer
  TCCR1B |= (1 << CS12);    // 256 prescaler 
  TIMSK1 |= (1 << TOIE1);   // enable timer overflow interrupt
  interrupts();             // enable all interrupts
}

ISR(TIMER1_OVF_vect)        // interrupt service routine 
{
  TCNT1 = timer1_counter;   // preload timer
  s++;
  //digitalWrite(ledPin, digitalRead(ledPin) ^ 1);
}

void loop()
{
 
 if(digitalRead(in_ir) == LOW) {//read rpm senssor
   rpm_read++;
   while(digitalRead(in_ir) == LOW){;}
 }

  if((rpm_read * 12) > rpm_set){
       pwm_duty++;
       if(pwm_duty > 65000){pwm_duty=65000;}
  }
  else {
       pwm_duty--;
       if(pwm_duty < 1){pwm_duty=1;}
  }

 if(pwm_timing < 10){
      digitalWrite(ledPin, LOW);
      digitalWrite(motor, LOW);
 }
 if((pwm_timing > 10) && (pwm_timing > pwm_duty)){
      digitalWrite(ledPin, HIGH);
      digitalWrite(motor, HIGH);
      pwm_timing=0;
      delay(10);
 }
 pwm_timing++;
 
    if(s%5==0){
      if(rpm_read_status == 0){
        lcd.setCursor(8,1);
        lcd.print("                ");
        lcd.setCursor(8,1);
        lcd.print("R=");
        lcd.print((rpm_read * 12)); 
        delay(10);
        rpm_read=0;
      }
      rpm_read_status=1;
    }
    else {rpm_read_status=0;}
    
    if(s%2==1){
      lcd.setCursor(0,1);
        lcd.print("        ");
       lcd.setCursor(0,1);       // sets the cursor at column 2 row 0
        lcd.print("S=");
        rpm_set=analogRead(adc_input); // reads the sensor output
        lcd.print(rpm_set); 
        delay(10); 
    }
   
}