LCD 4x20 HD44780

[paul borgmeier]

If you do not want to damage your 4x20 then read the 4x20 datasheet before trying anything else. I have several brands of 4x20s in use and none require a negative voltage on the contrast pin. Yours could be different but read the datasheet first.

Good Luck,

Paul Borgmeier
Salt Lake City, Utah
USA

[inteco]

Thanks for reply.

In fact, I read the datasheet, but somehow it just different from the real world. Anyway, just burn 1 because I plugged in the wrong cable which power up the LCD with 10 volts.

The contrast, indeed need negative voltage of up to -5.7 vdc with relative
to 0/gnd. Whereas the Vdd remain at 5.1 Vdc.

The LCD is made by OPTREX model DMC20481.

[inteco]

Extra Information :
There won't be any need to
DEFINE LCD_LINES 4

PBPro will work too if with DEFINE LCD_LINES 2.

Not really sure if the DEFINE LCD_LINES actually applied.

[paul borgmeier]

snip ....
The contrast, indeed need negative voltage of up to -5.7 vdc with relative
to 0/gnd. Whereas the Vdd remain at 5.1 Vdc.

The LCD is made by OPTREX model DMC20481.
... end snip

Wow - something is not right because my DMC20481 uses a + voltage for contrast. See the attached snippets from my DMC20481 datasheet.

Thoughts?

Paul Borgmeier
Salt Lake City, Utah
USA

[inteco]

yup,
this is the one I got, but it just don't work with + voltage.
I have 6 pieces of these, tried them all, and they all need
neg voltage.