Anyone use a Displaytech 204 LCD 4X20?

Archiver

Anyone use one? They're on sale at my electronics parts store and I'm
wondering if they are Hitachi 44780 compatible.

Any info apprecitated

thanks

elfa

Archiver

--- In basicstamps@yahoogroups.com, "faulke" <faulke@y...> wrote:
> Anyone use one? They're on sale at my electronics parts store and I'm
> wondering if they are Hitachi 44780 compatible.
>
> Any info apprecitated
>
> thanks
>
> elfa

Looking at the spec sheet at

http://www.displaytech.com.hk/

it appears they use the HD44780 protocol.

The one thing that I couldn't find is whether the voltage on term 3
(for contrast) is nominally +0.3 VDC or it requires a negative bias.

If it requires a negative bias, you might use a ICL7662 or TC7662 to
generate -5.0 from +5 VDC and feed this to terminal 2 of the LCD using
a series potentiometer of 4.7K.

If they have 16 terminals, they may well have an LED backlight as well.

Peter H Anderson, http://www.phanderson.com/stamp/

Archiver

Typically the expanded temperature range LCD's are the one's which
require the negative contrast voltage. Most of the others will work fine
by grounding the contrast pin, although a 10k pot used as a voltage
divider will allow you to adjust the contrast to just about any viewing
angle.

If you need a negative contrast voltage and have a MAX232 chip on board,
you can suck -9 volts off it for this purpose.

> > Anyone use one? They're on sale at my electronics parts store and I'm
> > wondering if they are Hitachi 44780 compatible.


> Looking at the spec sheet at
>
> http://www.displaytech.com.hk/
>
> it appears they use the HD44780 protocol.
>
> The one thing that I couldn't find is whether the voltage on term 3
> (for contrast) is nominally +0.3 VDC or it requires a negative bias.
>
> If it requires a negative bias, you might use a ICL7662 or TC7662 to
> generate -5.0 from +5 VDC and feed this to terminal 2 of the LCD using
> a series potentiometer of 4.7K.
>
> If they have 16 terminals, they may well have an LED backlight as well.

Archiver

Thanks for the reply.
Pin 3 can be grounded for max contrast (which is what
I did). My problem is that it won't work with a
program written for a Hitachi 44780 LCD and I don't
know if I have a bad display and will be forced to buy
another. When I checked the display codes for it, it
matches that of the 44780.

I emailed DisplayTech and asking the simple question
if it was 44780 and all they did was send me a spec
sheet without comment. But the spec sheet indicates
44780 display codes.

elfa

--- pha555 <pha@p...> wrote:
> --- In basicstamps@yahoogroups.com, "faulke"
> <faulke@y...> wrote:
> > Anyone use one? They're on sale at my electronics
> parts store and I'm
> > wondering if they are Hitachi 44780 compatible.
> >
> > Any info apprecitated
> >
> > thanks
> >
> > elfa
>
> Looking at the spec sheet at
>
> http://www.displaytech.com.hk/
>
> it appears they use the HD44780 protocol.
>
> The one thing that I couldn't find is whether the
> voltage on term 3
> (for contrast) is nominally +0.3 VDC or it requires
> a negative bias.
>
> If it requires a negative bias, you might use a
> ICL7662 or TC7662 to
> generate -5.0 from +5 VDC and feed this to terminal
> 2 of the LCD using
> a series potentiometer of 4.7K.
>
> If they have 16 terminals, they may well have an LED
> backlight as well.
>
> Peter H Anderson, http://www.phanderson.com/stamp/
>
>
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