John Payson wrote:
>
> >       What aboat those special driving voltages that are needed in
> >       LCD? I haven4t yet done much research to know how LCD4s actually
> >       work, but I think the driver sends some kind of A.C. voltage.
> >       Wether it4s sine- or square wave, I don4t know..
>
> If you are not multiplexing LCD's, the driving waveform for a lit LCD segment
> is simply a square wave that goes between [positive some voltage] and [nega-
> tive some voltage], relative to the common terminal.  The simplest way to get
> this is to drive the common wire with a 5-volt square wave and drive the seg-
> ments either in-phase or out-of-phase.

          No, I4m not. I just have these 39 segment displays with 1 common,
        and I need to drive max. 37 segments with a pic that can control 32.
          Somebody suggested me to use XOR4s for this "extension", but that
        way I can4t get that negative side of voltage. The way he said was
        to connect one common to other input of XOR, and other input to
        PIC4s output pin. Then the XOR4s output goes to LCD4s input.
        I think I4ll try that tomorrow..

-Jiri K.