LCD Plan

Connecting an LCD to Arduino is quite simple. Arduino provides an LCD library for interfacing HD44780 compatible LCD drivers. Here is my wiring plan:

interfacing an LCD

RS, R/W and E are control signals and they are directly connected to Arduino. We might not need the R/W signal and we can connect it to the ground. Lets see.
D4, D5, D6, and D7 are data lines. It is possible to communicate with the HD44780 via 4 data lines instead of 8. This way we can save digital I/O pins on the Arduino.
K and A are two pins for the back light LED. I’m not sure how much current it will need, so I try 450 ohm current limiting resistor  first and if the light is too dim I put something smaller.
The Vo pin is for setting the contrast of the LCD. We put a trimmer potentiometer there. 2.2 Kohm is a good guess. If that is not enough I will put something bigger.

I already ordered a blue display. When it arrives, I will set this up on a breadboard and I will try the hello world example form Arduino. If you go ahead and try this before I make my experiment, make sure that you change the hello world example according to your wiring. You might use different Arduino pins than the example.