> Others are telling you about the Vlcd pin. This is to bias the LCD
> backplane itself. They are warning you that this pin should not be
> left unconnected. It should be tied to ground through a low value
> (about 330 to 2K ohms) resistor.

Most LCD datasheets show a 5k or 10k pot connected between
Vcc and Vss with its wiper to Vo (contrast pin). In practise, that's
a waste of time. The simplest way is to wire Vo straight to Vss, but
the best contrast I've found generally is to have Vo a touch above
Vss. For this I use a 47R between Vo and Vss, and a 4k7 between
Vo and Vcc. With Vo unconnected it sits way above the maximum
contrast voltage for any degree of readability
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