LPT to LCD interface problem

[BluEagle91]

Hello everybody,
i am new over here, and i need desperate help.

I have an OPTREX DMC 20203 2x20 characters LC display.
It has HD44780 chip.
I used direct LPT to LCD wiring, and it wont work, i checked and rechecked wiring. I have done a million setups in my PC but it wotn work, for software i use LCD Smartie 5.3. LPT port is EPP as suggested in software FAQ. But it wont work.

I know HD44780 is the simplest, but i am getting very angry, and this LCD will go to garbage soon.

Any ideas?
Thanks.

 

[ericgibbs]

Hello everybody,
i am new over here, and i need desperate help.

I have an OPTREX DMC 20203 2x20 characters LC display.
It has HD44780 chip.
I used direct LPT to LCD wiring, and it wont work, i checked and rechecked wiring. I have done a million setups in my PC but it wotn work, for software i use LCD Smartie 5.3. LPT port is EPP as suggested in software FAQ. But it wont work.

I know HD44780 is the simplest, but i am getting very angry, and this LCD will go to garbage soon.

Any ideas?
Thanks.

hi,
Which PC operating system are you running.? Windows etc

 

[BluEagle91]

Micorosft Windows XP Service Pack 2

 

[ericgibbs]

Micorosft Windows XP Service Pack 2

hi,
Do you have the DDL's in the Windows/System folder that enable programs to access the parallel port, that is blocked by XP.?

EDIT:
Attached a zip file which has two *.dll's, unzip and move the dll's to the C:\Windows\System folder.

Retry using the LCD port program.

 

[BluEagle91]

I will try. but i have an nt driver for lpt access. something that is wriiten on site of LCD smartie. But i will try this now.

 

[BluEagle91]

no my dear friend, it did not helped. i will try now on difirent computer, bu on this one i have only a squares in first 20 squares. then after couple of minutes a full lcd of the squares, and it takes aprox 600mA, on 7 volts. that is power required for this LCD.

 

[ericgibbs]

I will try. but i have an nt driver for lpt access. something that is wriiten on site of LCD smartie. But i will try this now.

hi,
Tried to locate/download the Smartie, all I can get is the *.exe file not the source code.
I've no intention of running a unknown.exe on my PC, do you have the source code.?

 

[BluEagle91]

i downloaded my software from

LCD Smartie - A free open-source LCD program!


maybe thats why it wont work. what program do you recommend to be used for this application.

It still doesnt work.

 

[ericgibbs]

i downloaded my software from

LCD Smartie - A free open-source LCD program!


maybe thats why it wont work. what program do you recommend to be used for this application.

It still doesnt work.

hi,
Have you tried any of these.?

lcd on a PC parallel port - Google Search

 

[BluEagle91]

i`ll check them out.

 

[ericgibbs]

i`ll check them out.

Can you explain in what way is the LCD not working.?

Can you see the black pixel blocks.?
Have you fitted a contrast pot, does RW need to be connected to 0v.?

 

[BluEagle91]

Yes, The Blocks Are There.
I Am Now Trying With Different Voltages, I Think That Is Problem.

 

[ericgibbs]

Yes, The Blocks Are There.
I Am Now Trying With Different Voltages, I Think That Is Problem.

I havn't seen the PC parallel to LCD interface, I assume you have a cable of not more than 1mtr long and that you have 74LS06 or 07 buffers with pullup resistors.???

The HDLCD controller is normally +5V

 

[BluEagle91]

NO I DON`T.
oOk if i put an buffer it should work normally?
And my lcd is powered with +7.2V that is what says in it`s datasheet by manufacturer.

 

[ericgibbs]

NO I DON`T.
oOk if i put an buffer it should work normally?
And my lcd is powered with +7.2V that is what says in it`s datasheet by manufacturer.

hi,
Can you post the circuit showing how the LCD is connected to the paraport.?

How long is the para cable.?

Do you have a LCD datasheet you could also post.?

 

[BluEagle91]

sorry for long time to respond, i have been bussy, i am a student you know.
e schematic yes here it is


you can find datasheet overhere.

DMC20203 (Optrex) - Lcd Module Specification


i have modified a schematic for power source, i do not use backlight, that is the only modification.
This is my first LCD project, i am working with computers usualy but i want to enter this kind of electronics, so be free to tell any mistake i made, even it is very funny.

 

[ericgibbs]

sorry for long time to respond, i have been bussy, i am a student you know.
e schematic yes here it is
View attachment 24089

you can find datasheet overhere.

DMC20203 (Optrex) - Lcd Module Specification


i have modified a schematic for power source, i do not use backlight, that is the only modification.
This is my first LCD project, i am working with computers usualy but i want to enter this kind of electronics, so be free to tell any mistake i made, even it is very funny.

hi,
Have just downloaded your data, will go thru it, get back to you.
It will be tomorrow, its now19:30 UK time.

You didnt say how long the cable from PC to LCD interface is.?

 

[ericgibbs]

hi,
Looked thru the data.
It appears your LCD requires a -V for the Vee.
The Controller is a standard HD44780 but the drivers and the biassing show that a -Vee is required in order to make the pixels visible.
Look at the attached dwgs.

The LED backlight requires a fairly high current, DONT try to switch the LED cathode with the parallel port. I have removed that link from your sketch

When you have wired the LCD 10K contrast pot as per the datasheet, try adjusting the pot until you can see the black pixel blocks.

Let me know how it goes.

EDIT: Have you downloaded port95nt.exe from that Smartie site.?

 

[BluEagle91]

i will try this today, yes i have downloaded port95nt.exe, an installed it.

 

[BluEagle91]

well i made connections as you specified. and i see the black boxes, but the text is not going. i aplied 5 and -5 volts, from external power supplays, current is about 100 mA. i have backligh but i do not have text.