#include <LiquidCrystal_I2C.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4
#define TREF        0

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

char line[LCD_COLUMNS+1];

void setup() {
  // Init
  lcd.init();
  lcd.backlight();

}


void loop()
{
  int val;
  val = analogRead(TREF);
  val = map(val, 0, 1023, 10, 40);     // scale it to use it with the servo (value between 0 and 180)

  // Print something
  sprintf(line, "Tref: %d", val);
  lcd.setCursor(0, 0);
  lcd.print(line);
  lcd.setCursor(0, 1);
  lcd.print("T:");
}