#include <LiquidCrystal.h>

// Define the number of characters on each row
#define numCharacters 16

// Define the scroll delay variables
int i = 0;
long prevTime = 0;
long crtTime = 0;
long scrollInterval = 100;

// Initialize 16x2 LCD display:
// pin 1 - Reset (RS)
// pin 2 - Enable (E)
// pin 3 - D4
// pin 4 - D5
// pin 5 - D6
// pin 6 - D7
LiquidCrystal lcd(4, 2, 5, 18, 19, 21);

void setup() {
  Serial.begin(115200);

  lcd.begin(16, 2);
  
  lcd.setCursor(0, 0);  // Start from top left
  lcd.print("Scrolling text");
  delay(2000);          // Pause for 2 seconds
}

void loop() {
  // Get the current time in ms since the program started
  crtTime = millis();
  // Determine if the scroll interval has elapsed
  if (crtTime - prevTime > scrollInterval) {
    // Update the previous scroll time to the current time
    prevTime = crtTime;
    // Scroll the display one position to the right
    lcd.scrollDisplayRight();
    // Increment the psoition counter
    i++;

    // If the position counter is higher or equal to the 
    // number of characters on each row, the text is outside
    // the visible area so reset it to the outside of the
    // visible are in the other direction
    if (i >= numCharacters) {
      for (int j = 0; j < 2*i; j++) {
        lcd.scrollDisplayLeft();
      }
    }
    // Reset the position counter
    i = -numCharacters;
  }
  delay(10); // this speeds up the simulation
}