Yes, it needs a negative supply, which makes it work well.

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A member of the PI-100 Club:
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On Tue, 23 Feb 1999, Kevin Cantrell wrote:

> I bought 5 and am happy with them.  The have a standard Hitachi 44780
> controller.  The 22-pin connector is a little funny, but they supply the
> pinouts.  The part only has data bits 4 through 7, so you are limited to
> four bit mode.  The contrast is OK with pin 16 at 0 V, but I can't seem to
> increase it.  I think I may need a negative suppy.
>
> Kevin
>
>
> At 11:18 AM 2/23/99 -0600, you wrote:
> >MPJ has some 16x2 lcd displays, Picview PC066PGL, on sale cheap. Would
> >these be OK for playing around with as learning tools for a 16f84?
> >
> >Harley L. Miller     hmiller@sound.net
> >
> Kevin Cantrell
> Oregon State University
> Department of Chemistry
> 153 Gilbert Hall
> Corvallis, Oregon 97331-4003
> USA
> Voice: (541) 737-4528
> FAX : (541) 737-2062
>