Electronics NEED HELP WITH LCD WIRING plz!!!!!!! quick!!!!!!

OK this is my LCD

Seiko L1642B1L

heres its data sheet

http://www.eio.com/l1682.pdf

ok so I dont have any pots, so do i NEED resistors?

ok so is this what i do?

Pin 1 is GND
Pin 2 is +5V
Pin 3 is contrast right?

so i take a molex connector, then i Wire pin 1 to a black wire, then pin 2 to the red wire, and pin 3 to the other black wire. Is that correct? or do i wire pin 3 directly to pin 1?

So grounding pin 3 will give max contrast, what does it look like?

ok and then pins 15 and 16 are the LED Backlight, how do i wire those up? which pins do i connect them to?

ALSO, Do i need to have a Printer parallel cable, one with the parallel port that plugs into the computer, and has the centronics connector on the other end, or can i just use any parallel cable? Because i dont have any with a centronics end (thats not in use) all i have are db 25 pin male, extension (both ends are males, with the pins sticking out) so can i just use that? Or do i have to use one with a centronics conector on the end?

ok quick summary

pin1 goes to black wire on molex
2 goes to red
3 goes to other black wire?

then where do pins 15 and 16 connect to?

then do i NEED a cable with the centronics connector? or can i use a db25 male pin to db25 male pin extension (both ends are the sides u plug into computer parallel ports)

please help!!!!! pzlplzplzplpzlpzlplzz

 

OMG!!! I'd better reply quickly!!!!!11

Pin3 can be connected straight to Pin1 if you want maximum contrast, which is usually fine for these types of LCD's. If the link in my sig is still working, the LCD on my controller has Pin3 connected straight to ground for max contrast.

You will need a resistor for the backlight. Use a 10 ohm 0.5W resistor. Pin 16 to ground/pin 1. Pin 15 -> resistor -> +5V or Pin 2.

You can use any lead with DB25 connector, provided it has enough pins connected. The fatter the cable, the more likely this is...

 

well wouldnt a db25 conector have 25 pins? lol

ok well, do i have to connect pin 3 to pin 1 or can i just connect it to a ground/black wire on a molex?

k so i NEED the resistor? dammit i dont have any resistors here at all hehe, but do i NEED them? can i just wire it directly to pin 2?

 

Yes, you need the resistor for the LED backlight (10 Ohm was correct for that LCD, it has forward voltage of 4.1V and 100mA rating). If you dont, you burn out the backlight.

Second, some people have had no problems with tying the contrast voltage to ground. I think this is a mistake. Each and every LCD has variance for its contrast. Using a 5k potentiometer is the best way to adjust the contrast. If you dont use the pot, then the contrast will be set and possibly make the LCD only viewable at a certain funky angle. These parts are not expensive, you can locate the resistor and pot for less than a buck. Thats much easier than trying your hardest to bypass these components.

 

ok, hold on arent i suppose to use a 10k or 100ohm pot?

the 10k is for backlight isnt it? and the 100ohm is for contrast? Ok so should i use both a pot and the 10 ohm for the back light? does digikey sell 10 ohm resistors?

Can someone give me a link to all the parts id need? I guess ill just order them, 10 bucks shouldnt be too hard to make up

 

I need help with annoying people who don't know how to turn caps-lock off, plz, quick.

 

10 Ohm resistor for BACKLIGHT.

10k pot for CONTRAST.

Ive already looked at a datasheet better than the one you linked. Those are the recommended values.

 

Uhh.....what?
[/spam]

 

so i dont need to get a 100 ohm pot? i thought that the 10k was for the backlight

 

The datasheet recommends a 1k to 10k pot for the contrast.

If you use anything more than 10 Ohms for the backlight, there will not be enough current to light up the LEDs. They have a forward voltage of 4.1V and require 100mA for proper lighting:

5V - 4.1V for LEDs = 0.9V for the current limiting resistor.

0.9V @ 0.1A means: 0.9V/0.1A= 9 Ohms, or the closest value being 10 Ohms. Anything higher will dim the backlight too much, anything lower will burn them out.

0.9V * 0.1A = 0.09 Watts. A 1/4watt resistor will do fine.

 

lol i didnt understand any of that haha

Does digikey have the right 10 ohm resistor? Can i get a link?

Some guy is gonna send me a 100ohm pot (hopefully) and thats for the backlight or the contrast?

and im probly going to pick up a 10k at radioshack

 

the 100 ohm pot should be used with the backlight it would hardly do any difference with the contrast.

 

Not true. It would still work for contrast adjustment, as you're still making a potential divider with the full 5V swing, you'd just be wasting 5²/100 = 250mW which the pot may not be able to handle.

 

ok so i need

100ohm pot for backlight?

10kohm pot for contrast

and a 10ohm resistor for the back light? that would be the rlimit thing?

 

ok i tried using a 100 ohm pot with contrast and it changed very little so i won't argue with that the 100 ohm pot goes to backlight the 10 kohm pot goes to the contrast. and forget the 10 ohm resistor FORGET... it's only needed if you'll be using the backlight pot on a regular basis and other ppl have access to it (you should be able to remember not to crank it up to max )

 

It'd argue that it's important to keep the 10 ohm resistor in series with the output from the 100 ohm variable resistor. If you don't use it you'll not know if you're damaging the backlight...

At least if you keep it, you'll know you can vary the backlight over the whole range of the pot. I don't know about you, but I'd rather spend 0.3p on a 10 ohm resistor instead of needing a new backlight...

Bboy_Jon, your list is correct.

 

I have no idea where anyone suggested a 100 Ohm pot for anything.

Its very simple:

5V--->10 Ohm resistor---->pin 15

Ground--->pin 16


Ground---->pin1 and outer leg of 10k pot

5V---->pin2 and other outer leg of 10k pot

middle leg (wiper) of 10k pot---->pin3

The other pins depend on what software your gonna use, but they go to a db25 connector.

 

I think he wanted a variable brightness backlight using a 100 ohm pot. Obviously it's not required though.

Just keep that 10 ohm fixed resistor in there and you're fine

 

ya ill probly get the resistor too

Mainly because at digikey id be getting a 10k and maybe the 100ohm pot which are 89 cents each, and then the shipping is like 5 bucks, theres no way in hell im gonna pay 5 bucks to ship 2 tiny lil thangs haha

 

hmm digikey doesnt have a 10ohm resistor in stock, and the one they do have is 1k watt would it still work?

gfuess i cant get a resistor, so i just gotta get the pot

edit: the 100ohm is out of stock too, can someone give me links to the parts at another site, i dunno where to look on all-electronics