LCDInfo.com

Hey guys,

I'm trying to get this damn LCD working but it just doesnt want to work.

Here is the datasheet for it,
http://btmg.freehostia.com/files/GM3202405.pdf

Pin 1 - Vss - 0V
Pin 2 - Vdd - +5v
Pin 3 - Vo - ?
Pin 4 - X
Pin 5 - X
Pin 6 - X
Pin 7 - X
Pin 8 - X
Pin 9 - X
Pin 10 - X
Pin 11 - X
Pin 12 - X
Pin 13 - X
Pin 14 - X
Pin 15 - 0V
Pin 16 - 0V
Pin 17 - Should be -22v but its not
Pin 18 - SEL1 - 0v (8080 Series)
Pin 19 - Frame GND - 0V
Pin 20 - NC

What im not to sure about is this Vee (contrast) crap.

It seems as though it generates Vee negative voltage using in built circuitry but after connecting a 10k Var resistor, with middle to Vo, and the others with one to Vdd and the other to Vee.

Now ive pulled out my multimeter and checked Vee and its not negative, even when i disconnect it and just have power to the LCD or if i connect all the pins. I instead get a positive voltage ranging from ~0v to 5v.

When i turn the POT, i dont see any contrast change either.

Any help??

I have the exact same problem with my Sed 320x240. Generating an external -20v (connected to V0, Vee N/C) may be your only option.

Interesting...

Was hoping to avoid that. I did notice though that the PIN on the LCD for Vee actually goes to a part of the circuit which has components removed, so im assuming that the negative voltage generation circuit has been removed.

I did notice in the datasheet that it said (Optional), maybe that will explain it.

Anyways, off to Maxim-ic FREE samples!

Please if you reach any thing about this subject tell me

i know the post is old but i hope you can help because i am at the same problem