Today I received the LCD screen i ordered from China. At only $5.39 with free shipping i just couldn't resist. It's a 20 x 4 White on Blue screen with backlight and a piggy-backed i2c interface. So hooking it up to your Arduino only takes up the two pins (SCA and SCL).

But I had a lot of trouble getting it to actually display some text. I tried various libraries and examples but nothing seemed to work. After about two hours of increasing frustration I suddenly remembered that LCD screens are illegible if the contrast isn't properly set. So i carefuly turned the trimmer on the i2c interface and suddenly, as if by magic, my text appeared on the screen. Phew!

This screen will be of great value to the end product but also as a debugging tool.