// This is the (old) default library.
// It seems to work with a Raspberry Pi
//
// Note: In Real Life, there must be a I2C level shifter.

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd( 0x27, 16, 2);
LiquidCrystal_I2C lcd2( 0x28, 16, 2);

void setup()
{
  Serial.begin(115200);
  while (!Serial) // wait for serial port to connect. Needed for native USB
  {
    delay(10); 
  }
  Serial.println( "The sketch has started.");


  Wire.begin();              // use the default, GPIO4 = SDA, GPIO5 = SCL

  Serial.print( "Scanning for I2C addresses: ");  
  for( int i2cAddress = 1; i2cAddress <= 127; i2cAddress++)
  {
    Wire.beginTransmission( i2cAddress);
    int error = Wire.endTransmission();
    if( error == 0)
    {
      Serial.print( "0x");
      if( i2cAddress < 0x10)
        Serial.print( "0");
      Serial.print( i2cAddress, HEX);
      Serial.print( ", ");
    }
    delay( 1);
  }
  Serial.println( "Ready.");

  // Initial text on the first display
  lcd.init();
  lcd.backlight();           // turn on backlight

  lcd.setCursor( 0, 0);
  lcd.print( "It is working");

  lcd.setCursor( 0, 1);
  lcd.print( "0x");

  // Write something on the second display
  lcd2.init();
  lcd2.backlight();           // turn on backlight
  lcd2.setCursor( 0, 0);
  lcd2.print( "Second display");
}

void loop()
{
  lcd.setCursor(2,1);
  char buffer[20];
  sprintf( buffer, "%08lX", millis()); // <- I did not check the format, it might be right
  lcd.print( buffer);
  delay( 20);                          // slow down the sketch
}