I just bought a 16x2 and I2C interface to it. Everything seems to be working fine (not sure if 4 or 8 bit?) but the only problem is refresh rate. When scrolling or fast changing text it is not visible because the “shadow” of the previous char. The only way to make it better is to set contrast with potentiometer to very low that text is actually black not white (it is negative display BLUE with White text).
Do you know what is the problem? I am seeing all of those youtube videos where they are even doing some nice animations with very good FPS but I am not able to display single text faster than ~800ms.