Arduino Omomierz

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 20, 4);

const int res0 = 5, res1 = 4, res2 = 3, res3 = 2, analog = 7;
const double toVoltage = 0.004887586;

void setup() {
  const byte ohmChar[] = {0x0E, 0x11, 0x11, 0x11, 0x0A, 0x0A, 0x1B, 0x00};

  pinMode(res0, OUTPUT);
  pinMode(res1, OUTPUT);
  pinMode(res2, OUTPUT);
  pinMode(res3, OUTPUT);

  digitalWrite(res0, LOW);
  digitalWrite(res1, LOW);
  digitalWrite(res2, LOW);
  digitalWrite(res3, LOW);

  lcd.begin();
  lcd.createChar(0, ohmChar);
  lcd.home();
}

void loop() {
  int analogVal0, analogVal1, analogVal2, analogVal3, resistor;
  double Vout, ohm;

  digitalWrite(res0, HIGH);
  digitalWrite(res1, LOW);
  digitalWrite(res2, LOW);
  digitalWrite(res3, LOW);
  analogVal0 = analogRead(analog);
  delay(25);

  digitalWrite(res0, LOW);
  digitalWrite(res1, HIGH);
  digitalWrite(res2, LOW);
  digitalWrite(res3, LOW);
  analogVal1 = analogRead(analog);
  delay(25);

  digitalWrite(res0, LOW);
  digitalWrite(res1, LOW);
  digitalWrite(res2, HIGH);
  digitalWrite(res3, LOW);
  analogVal2 = analogRead(analog);
  delay(25);

  digitalWrite(res0, LOW);
  digitalWrite(res1, LOW);
  digitalWrite(res2, LOW);
  digitalWrite(res3, HIGH);
  analogVal3 = analogRead(analog);
  delay(25);

  lcd.clear();
  lcd.setCursor(0, 3);

  if(analogVal3 >= 500) {
    Vout = analogVal3 * toVoltage;
    ohm = Vout / ((5-Vout-0.5) / 100000); //  Voltage drop ~0.5V
    resistor = 3;

  } else if(analogVal3 < 500 && analogVal2 >= 450) {
    Vout = analogVal2 * toVoltage;
    ohm = Vout / ((5-Vout-1.0) / 10000);  //  Voltage drop ~1.0V
    resistor = 2;

  } else if(analogVal3 < 450 && analogVal2 < 450 && analogVal1 >= 450) {
    Vout = analogVal1 * toVoltage;
    ohm = Vout / ((5-Vout-0.475) / 1000); //  Voltage drop ~0.475V
    resistor = 1;

  } else if(analogVal3 < 450 && analogVal2 < 450 && analogVal1 < 450 && analogVal0 >= 0) {
    Vout = analogVal0 * toVoltage;
    ohm = Vout / ((5-Vout-1.255) / 100);  // Voltage drop ~1.255V
    resistor = 0;
  }

  lcd.setCursor(0, 0);

  if(ohm >= 0 && ohm < 1000) {
    lcd.print(ohm);
  } else if(ohm >= 1000 && ohm < 1000000) {
    lcd.print(ohm/1000);
    lcd.print('k');
  } else if(ohm >= 1000000) {
    lcd.print(ohm/1000000);
    lcd.print('M');
  }


  lcd.write(0);


  lcd.setCursor(13, 0);
  lcd.print("V0:");
  lcd.print(analogVal0);

  lcd.setCursor(13, 1);
  lcd.print("V1:");
  lcd.print(analogVal1);

  lcd.setCursor(13, 2);
  lcd.print("V2:");
  lcd.print(analogVal2);

  lcd.setCursor(13, 3);
  lcd.print("V3:");
  lcd.print(analogVal3);

  lcd.setCursor(0, 3);
  switch(resistor) {
    case 0: lcd.print("100");   break;
    case 1: lcd.print("1k");    break;
    case 2: lcd.print("10k");   break;
    case 3: lcd.print("100k");  break;
  }
  lcd.write(0);

  delay(1000);


}