#include <LiquidCrystal_I2C.h>
#include <Wire.h>

LiquidCrystal_I2C lcd(0x27, 20, 4);

#define atas digitalRead(12)==0
#define bawah digitalRead(11)==0
#define enter digitalRead(10)==0
#define back digitalRead(9)==0

char state;

int PS_hz = 0;
int STB_hz = 0;

float coef;

//millis
uint32_t LCD;

void setup() {
  Serial.begin(9600);
  pinMode(12, INPUT_PULLUP);
  pinMode(11, INPUT_PULLUP);
  pinMode(10, INPUT_PULLUP);
  pinMode(9, INPUT_PULLUP);
  lcd.init();
  
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Selamat Datang");
  delay(1000);
  lcd.clear();

}

void loop() {
 if (millis() - LCD >= 200){
   LCD = millis();
   show();
 }

}


void show(){
  switch(state){
    case 0:
    lcd.setCursor(0,0);
    lcd.print("Freq");

    lcd.setCursor(0,1);
    lcd.print("RPM");

    lcd.setCursor(10,0);
    lcd.print("Koef");

    lcd.setCursor(10,1);
    lcd.print("GPS");

    lcd.setCursor(8,0);
    lcd.print("<");

    if(atas){
      lcd.clear();
      state = 3;
    }else if(bawah){
      lcd.clear();
      state = 1;
    }else if(enter){
      lcd.clear();
      state = 4;
    }
    break;

    case 1:
    lcd.setCursor(0,0);
    lcd.print("Freq");

    lcd.setCursor(0,1);
    lcd.print("RPM");

    lcd.setCursor(10,0);
    lcd.print("Koef");

    lcd.setCursor(10,1);
    lcd.print("GPS");

    lcd.setCursor(8,1);
    lcd.print("<");

    if(atas){
      lcd.clear();
      state = 0;
    }else if(bawah){
      lcd.clear();
      state = 2;
    }else if(enter){
      lcd.clear();
      state = 5;
    }
    break;

    case 2:
    lcd.setCursor(0,0);
    lcd.print("Freq");

    lcd.setCursor(0,1);
    lcd.print("RPM");

    lcd.setCursor(10,0);
    lcd.print("Koef");

    lcd.setCursor(10,1);
    lcd.print("GPS");

    lcd.setCursor(15,0);
    lcd.print("<");

    if(atas){
      lcd.clear();
      state = 1;
    }else if(bawah){
      lcd.clear();
      state = 3;
    }else if(enter){
      lcd.clear();
      state = 6;
    }
    break;

    case 3:
    lcd.setCursor(0,0);
    lcd.print("Freq");

    lcd.setCursor(0,1);
    lcd.print("RPM");

    lcd.setCursor(10,0);
    lcd.print("Koef");

    lcd.setCursor(10,1);
    lcd.print("GPS");

    lcd.setCursor(15,1);
    lcd.print("<");

    if(atas){
      lcd.clear();
      state = 2;
    }else if(bawah){
      lcd.clear();
      state = 0;
    }else if(enter){
      lcd.clear();
      state = 7;
    }
    break;

    case 4:
    lcd.setCursor(0,0);
    lcd.print("PS");

    lcd.setCursor(4,0);
    lcd.print(PS_hz);

    lcd.setCursor(0,1);
    lcd.print("STB");

     lcd.setCursor(4,1);
    lcd.print(STB_hz);

    if(back){
      lcd.clear();
      state = 0;
    }
    break;

    case 5:
    lcd.setCursor(0,0);
    lcd.print("PS");

    lcd.setCursor(4,0);
    lcd.print(PS_RPM);

    lcd.setCursor(0,1);
    lcd.print("STB");

     lcd.setCursor(4,1);
    lcd.print(STB_RPM);

    if(back){
      lcd.clear();
      state = 1;
    }
    break;

    case 6:
    lcd.setCursor(0,0);
    lcd.print("Koefisien RPM");

    lcd.setCursor(0,1);
    lcd.print(coef);

    if(back){
      lcd.clear();
      state = 2;
    }
    break;
  }
}

void countRpm(int hz, float pole){
  int RPM = (hz*120)/pole;
  return RPM;
}