#include <LiquidCrystal_I2C.h>

// Instantiate the counts
LiquidCrystal_I2C lcd(0x27, 16, 2);  // 3F the address of the LCD

#define rpmInput1 2
#define rpmInput2 3
#define rpmInput3 18

/* REMOVE REMOVE REMOVE REMOVE REMOVE REMOVE */
int switchPin1 = 11; // choose the input pin (for a pushbutton)
int switchPin2 = 12; // choose the input pin (for a pushbutton)
int switchPin3 = 13; // choose the input pin (for a pushbutton)
/* REMOVE REMOVE REMOVE REMOVE REMOVE REMOVE */

int rpm1 = 0;
int rpm2 = 0;
int rpm3 = 0;

double pulsesPerRev1 = 1.0;
double pulsesPerRev2 = 2.0;
double pulsesPerRev3 = 3.0;

unsigned long millisBefore;

volatile int counts1;
volatile int counts2;
volatile int counts3;

void setup(){

  Serial.begin(57600);
  Serial.println("Welcome to the Serial Monitor!");
  Serial.println("---------------------------------");

  attachInterrupt(digitalPinToInterrupt(rpmInput1), count1, FALLING);
  delay(1000);

  attachInterrupt(digitalPinToInterrupt(rpmInput2), count2, FALLING);
  delay(1000);

  attachInterrupt(digitalPinToInterrupt(rpmInput3), count3, FALLING);
  delay(1000);

/* REMOVE REMOVE REMOVE REMOVE REMOVE REMOVE */
  pinMode(switchPin1, INPUT); // declare as input 
  pinMode(switchPin2, INPUT); // declare as input
  pinMode(switchPin3, INPUT); // declare as input
/* REMOVE REMOVE REMOVE REMOVE REMOVE REMOVE */

  // Initialize the display
  lcd.init();
  lcd.init();
  lcd.backlight();
  lcd.noCursor();

  pinMode(rpmInput1, INPUT);
  pinMode(rpmInput2, INPUT);
  pinMode(rpmInput3, INPUT);

}//end setup


void loop() {
/* REMOVE REMOVE REMOVE REMOVE REMOVE REMOVE */
  analogWrite(switchPin1,110);
  analogWrite(switchPin2,100);
  analogWrite(switchPin3,120);
/* REMOVE REMOVE REMOVE REMOVE REMOVE REMOVE */

  if (millis() - millisBefore > 1000) {
    rpm1 = (counts1 / pulsesPerRev1)*60;
    counts1 = 0;
    rpm2 = (counts2 / pulsesPerRev2)*60;
    counts2 = 0;
    rpm3 = (counts3 / pulsesPerRev3)*60;
    counts3 = 0;
    millisBefore = millis();
  }
   delay(100);

  lcd.setCursor(4, 0);
  lcd.print("RPM 1: ");
  lcd.setCursor(11, 0);
  lcd.print(rpm1);

  lcd.setCursor(4, 1);
  lcd.print("RPM 2: ");
  lcd.setCursor(11, 1);
  lcd.print(rpm2);

  lcd.setCursor(4, 2);
  lcd.print("RPM 3: ");
  lcd.setCursor(11, 2);
  lcd.print(rpm3);
}

void count1() {
  counts1++;
}

void count2() {
  counts2++;
}

void count3() {
  counts3++;
}