A simple Arduino Sketch to let a marquee run through a LED panel.

ArduinoMarquee.ino

// Use LiquidCrystal library to communicate with LCD
#include <LiquidCrystal.h>

// Select the pins used on the LCD panel
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

// Define message to show
String message = "My future tweets will be in this format";

void setup() {
  // Set up the LCD's number of columns and rows
  lcd.begin(16, 2);
  
  // Print the message to the LCD
  lcd.print(message);

  // Wait a second
  delay(1000);
}

void loop() {
  // Scroll string length positions to the left to move it offscreen left
  for (int positionCounter = 0; positionCounter < message.length(); positionCounter++) {
    // Scroll one position left
    lcd.scrollDisplayLeft();
    // Wait a bit:
    delay(200);
  }

  // Reset curser after completely scrolled to the left
  lcd.setCursor(0, 0);
}