#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);


void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  lcd.clear();
  }


void loop() {
  int ADC_low = ADC_change(A0, 0); //  int ADC_low = analogRead(A0);
  int ADC_low_map = ADC_low;
  Serial.println(ADC_low);

  ADC_low_map = map(ADC_low_map, 0, 1023, 0, 100);
  lcd.home();
  lcd.print("Raw: ");
  lcd.print(ADC_low);
  lcd.print("   ");


  lcd.setCursor(0, 1);
  lcd.print("%: ");
  lcd.print(ADC_low_map);
  lcd.print("   ");


}


uint16_t ADC_change(uint8_t pin, bool HIGH_LOW) {
  //DIVISION FACTOR - 128
  //TRIGGER - Free Runng Mode
  //VOLTAGE REFERENCE - AREF, Internal Vref turned off

  if (pin >= 14 && pin <= 19) {
    pin -= 14;
  }

  uint16_t ADC_value = 0;

  ADMUX &= ~(1 << REFS0);
  ADMUX &= ~(1 << REFS1);
  ADCSRA |= (1 << ADEN);
  ADCSRA &= ~(1 << ADATE);
  ADCSRA |= 0b00000111;
  ADCSRA &= ~(1 << ADIE);
  ADCSRA &= ~(1 << ADIF);
  ADCSRB = 0b00000000;

  ADMUX &= 0b11110000;
  ADMUX += pin;

  if (HIGH_LOW == 0) {
    ADMUX &= ~(1 << ADLAR);
  }
  else {
    ADMUX |= (1 << ADLAR);
  }

  ADCSRA |= (1 << ADSC);
  while ((ADCSRA & (1 << ADIF)) == 0);

  if (HIGH_LOW == 0) {
    ADC_value = ADCL;
    ADC_value |= ADCH << 8;
  }
  else {
    ADC_value |= ADCH;
  }

  ADCSRA &= ~(1 << ADSC);
  return ADC_value;
}