I am having an Arduino Uno and I want to add a LCD to it. My LCD is a C2042A with I2C shield on it. I tried the LiquidCrystal_I2C library but it doesnt work. I am not getting any errors the LCD is just not showing the text. I just used the example code 'Hello World' from the library. I only changed the adress from 0x27 to 0x63 because I found that with the I2C scanner.

So all in all the LCD is connected right. It shows I2C mode which is also fine and it is find by the I2C Scanner code. Which library do I have to use that it will work? http://www.wentztech.com/filevault/Electronics/Arduino/

  • Do you see white squares on the first line, but not the second? If not, you have to adjust the contrast with the potentiometer.
    – Gerben
    Commented Aug 15, 2016 at 15:14
  • No when you turn the LED on it shows the standart text: LCD03 REVISION9 (next line) I2CMODE @ 0xC6
    – Number_987
    Commented Aug 15, 2016 at 15:23

1 Answer 1


0x63 is the correct address - the module is at 0xC6 which is the 8-bit equivalent of 0x63 (0x63 shifted left once for the read/write bit to be added).

The LCD03 uses its own custom I2C protocol, not compatible with the "normal" I2C LCD library. Instead you have to use their own special commands.

The commands are detailed here: http://www.robot-electronics.co.uk/htm/Lcd03tech.htm

There may be a library available that wraps those commands, I don't know, but you can just use the Wire library to send the commands you need to send.

  • ok that looks complicated can you write an example code how to for example turn the blacklight off with the wire library?
    – Number_987
    Commented Aug 15, 2016 at 16:29

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