Hello Charles,

"U12A and U12B is a 4066 analog switch. Only one is on at any given time. Depending upon the level of P3.5 will determine which one of the two is on."

No, I'm afraid not. The switches will both be on or off at any time. You need an inverter, as Slobodan suggested.

As for the display contrast, every standard character LCD I have ever worked with required a positive voltage for contrast control! Better check those datasheets :o) You could, perhaps, provide a jumper to select between a positive or a negative voltage.


Best regards,
Rob Klein.