// Quick and dirty example of scrolling text.
// I did not check if everything is correct.

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 20, 4);

char *scroll_text = "                This text is scrolling                ";
int index = 0;

void setup() 
{
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0); // upper 
  lcd.print("Static Text");
}

void loop() 
{
  // Select the characters.
  // Start with index, exactly 16 characters long.
  char buffer[20];
  strncpy(buffer, scroll_text + index, 16);
  buffer[16] = '\0';
  index++;
  if(index >= strlen(scroll_text)-16)
    index = 0;

  lcd.setCursor(0, 1); // lower
  lcd.print(buffer);

  delay(150);
}