Interfacting 4x40 HDD780 LCD with Printer port (Parallel Port)

Jarrod · 01-30-2002, 08:53 PM

I have just bought a 4x40 EL backlight LCD, and I have all the pinout information as listed below, but I still have NO idea how to interface it with my Printer Port. Please help me.
Pinouts:
--------
1 = switch (GND on switch closure)
2 = EL backlight
3 = EL backlight
4 = LCD bias (appr. -2.5V)
5 = 44780 Register Select
6 = 44780 R/W
7 = 44780 enable IC1 (top 2 rows)
8 = 44780 enable IC6 (bottom 2 rows)
9 = Vcc
10 = N/C
11 = N/C
12 = Gnd
13 = D0
14 = D1
15 = D2
16 = D3
17 = D4
18 = D5
19 = D6
20 = D7

Can anybody help me out with a wiring diagram or any information? Thank You.

bgoodman · 01-30-2002, 08:54 PM

http://www.mp3car.com/cgi-bin/ultima...search_forum=7

Jarrod · 01-30-2002, 11:21 PM

I have already tried to search existing posts, but as you should be able to tell, my pinouts are completely different to those on all the schematics that other people have used. So can anyone ELSE help me?

surfer6262 · 01-31-2002, 12:08 AM

This is the same position i am in, I found this....
http://www.mswanson.com/~nstuart/lcd/WinLCDhardware.htm

Jarrod · 01-31-2002, 12:32 AM

Thanx, but that diagram doesnt help me, it's the same as all the other ones I've seen....anyone else?

Fosgate · 01-31-2002, 01:33 AM

Dude I'll post the coresponding pins that will match normal layout that we have with standard LCD screen...
Only thing im at work now and i cant do it until i get home.
Check this this BB later on tonight.

[ 01-31-2002: Message edited by: Fosgate ]

Fosgate · 01-31-2002, 06:11 PM

Sorry dude had some problem with internet last night... Will try to do it tonight.

Jarrod · 02-01-2002, 05:05 AM

Can anyone please help me as I am sort of in a hurry.

Fosgate · 02-01-2002, 09:31 AM

1 = switch (GND on switch closure)
2 = EL backlight
3 = EL backlight
4 = LCD bias (appr. -2.5V)
5 = 44780 Register Select
6 = 44780 R/W
7 = 44780 enable IC1 (top 2 rows)
8 = 44780 enable IC6 (bottom 2 rows)
9 = Vcc
10 = N/C
11 = N/C
12 = Gnd
13 = D0
14 = D1
15 = D2
16 = D3
17 = D4
18 = D5
19 = D6
20 = D7

1 - > 13
2 - > EL Backlight around 100V AC
3 - > EL Backlight around 100V AC
4 - > -2.5v To drive the LCD
5 - > 11
6 - > 10
7 - > 9
8 - > 15
9 - > 14
10 - > N/C
11 - > N/C
12 - > GND pin 13
13-20 - > 1 to 8

Well here it is. Its pretty simple really
on the left side is your LCD on the right its the standard pin out.

Jarrod · 02-01-2002, 10:01 PM

thanx alot, but are you 100% sure those are the correct pinouts? because all the other 40x4 schematics say that R/S should go to pin 16 of the parallel port and you say it should be 11? It just doesnt seem right to me.
I have another question:
Where am I supposed to get 100V AC from and -2.5V (DC or AC?)

in order to connect my LCD to parallel port and run it in the car?

[ 02-01-2002: Message edited by: Jarrod Bell ]

Fosgate · 02-03-2002, 06:32 PM

Dude the number on the right are not the parallel port pins... its the pins of the standard 4x40 LCD screen another words you need a schematic on how to connect standard 4x40 LCD screen to parallel port and where ever you see the pins numbers for the standart LCD use the ones that i posted above instead... You know what ... It probably would be easier if i give you the pin outs for the parallel port instead of the standard LCD. Will try to do that tonight.
As for 100V its basically the output of your backlight inverter... you going to need one.
and for -2.5v that will be bit complicated... you might need to use Maxim chips to get that voltage or make a circut that will convert -5v from your computers supply to -2.5v

Jarrod · 02-03-2002, 08:35 PM

I'm goin to need a backlight inverter? What for? Where do I get one appropriate for my LCD in Australia? Any help on a circuit to get -2.5V from -5V input would be greatly appreciated.

MP3IAN by Ian Gregory · 02-03-2002, 11:05 PM

Good to see you also own a VL Berlina and are having exactly the same trouble as me!!!!
Bloody things! I used the schematic as mentioned before and i receive the two rows of blocks upon startup but i don't get any response by using lcdprint or lcdisplayer etc.

Rob · 02-04-2002, 02:50 PM

Quote:

Any help on a circuit to get -2.5V from -5V input would be greatly appreciated.[/QB]

There is a chip called an LM337T

I hope this is of some use.

Rob

Jarrod · 02-04-2002, 08:19 PM

The info on that chip says its adjustable from -1.2V to 30 something volts, which means it cannot go down to -2.5V which I require. Also, what voltage does it require to begin with?