I just connected a lcd 16x2 display to the raspberry pi (directly, no breadboard). I can display text and send command to it without problem. The only problem is that the text is black while it should be white (blue backlight). Any thought on how I could fix that? Thanks in advance!
Those HD44780 driven LCDs don't have reverse characters in their character set. If yours is displaying black text on the background, you are stuck with that.
— Well, you could undo the display frame and flip the polarizer, but most times, it's glued onto the glass. It's up to you if you find it worth a try. —
You end up with blue text on black then, of course. Cool? Not cool?
The "white text on blue" variant has a special blueish polarizer instead of a black one and a white backlight.