/*
  Arduino | coding-help
  one scroll line + one static line on I2C LCD1602 screen

  Giratina Musics(Road 2 Polyglot)
  December 10, 2025 at 5:38 PM

  https://forum.arduino.cc/t/16x2-lcd-one-line-scrolling-one-stationary/406501
*/

#include <LiquidCrystal_I2C.h>

const char firstLine[16] = "Static 1st line";
const char secondLine[39] = "Scrolling text on second line";

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  //lcd.print(firstLine);
}

void loop() {
  lcd.clear();
  //lcd.setCursor(0, 0);
  lcd.print(firstLine);
  lcd.setCursor(0, 1);
  for (int i = 0; i <= 16; i++) { //For the first 16 characters, simply print them to the LCD screen.
    lcd.write(secondLine[i]);
  }
  delay(1500); //Delay for 1.5 seconds so the user has time to read.
  for (int j = 17; j <= 39; j++) { //Now we begin printing from character 17 onward...
    lcd.write(secondLine[j]); //Write the j-th character (for now it will be off-screen).
    lcd.scrollDisplayLeft(); //Scroll the text left one character-space.

    //This is where things get tricky, because both rows will be scrolled. But we want row 1 to remain stationary!
    lcd.setCursor(j - 16, 0); //Set the cursor to the first character space on the first row [visually].
    // cursor space (0,0) has been scrolled off-screen!
    lcd.print(firstLine); //Re-print the row 1 message.
    lcd.setCursor(j + 1, 1); //Set the cursor one character space to the right of the last printed character on row 2.
    //  Which is visually one character space off-screen, in preparation for the next itteration.
    delay(300); //delay for .3 seconds so the user has time to read.
  }
}