Timeline's 40x4 Densitron character LCD

SuperMatty · 09-20-2001, 02:02 AM

I'm having a great deal of difficulty getting the Timeline Densitron 40x4 character LCD to work. I've been using BoominVolvo's schematic but having little luck in getting the display to do anything but power up the backlight. On the LCD pcb, pin 1 is labeled on the opposite side that the red wire on the ribbon cable is connected to, so which is really pin 1? I have tried wiring the LCD both ways but neither seem to work. It is possible I may have hooked it up the wrong way the first time and fried the controller though, I suppose.

I have pin3 connected to the ground instead of the wiper on the 10k contrast potentiometer just to ensure I would have full contrast, and similarly, I have no potentiometer connected to the backlight so that I would have full brightness. Any help is appreciated.

milesg · 09-20-2001, 06:31 AM

Okay, I'm having the same EXACT problem... here's a little more info on what I've tryed to do (and what happened):

First I soldered pins onto the LCD so that I can connect to the printer cable on not have to worry about soldering (and re-soldering) on the actual LCD if I make a mistake.

I then, Painstakingly (spelling?) figured out which wires on the ribbon correstpond with the 16 pins on the LCD with a multimeter(To answer one of your questions SuperMatty: it doesn't matter what the red line says, as long as it goes to the right place.)

I soldered a female printer port to a PCB and the socket that accomodates the 16 pins of the LCD display.

this PCB is where all the wires and pots come together.

I then split open an old keyboard and stripped the end off the cable... there were 4 wires, 2 of which were black and red. I was able to connect these directly to an extra LED that I had laying around, so I know that these are the + and - wires.

Then I connected the 2 keyboard wires to my assembly and tryed to get something to appear on the screen (via LCDprint.exe), without the Back Light.

Okay, so here's where it all goes to *****.
(BTW, I've double checked my wiring several times however, I'm not 100% sure of the 10k pot)

If the LPT cable is NOT connected (just expecting to see the black bars), nothing shows up and the two main controller chips on the back get hot... I promptly unplugged it!!

If the LPT cable IS plugged in, there are still no characters (junk or otherwise), and there is no excessive heat. (ran lcdprint and got nothing)

If I connect the Back Light to the assembly while the LPT cable is plugged in, it does NOT work. However, I gain a green beacon of hope when the LPT cable is removed.

If anyone could confirm that my pots are set up correctly, here's how they function based on my tests.

(firstly, I think the numbers are different on mine than on the scheme)

1,2, and 3....

if I connect 1 and 2 to my multimeter, I can see an obvious change in the values when I rotate the screw. the same is true if I connect the multimeter to 2 and 3 (only reverse values)... If I connect the multimeter to 1 and 3, I only get a constant value regardless of screw rotation.

how do my pins corespond with the 12and3 of the ones on Boomin's Scheme?

Sorry for the long-winded post
Any help would be GREATLY appreciated.
Thank you.

-Miles

moahdib · 09-20-2001, 02:17 PM

I suppose you guys are using the same circuit diagram for the 40X4 from seiko am I right? Arby was wiring these and selling them with 1k pots instead of 10k. I believe 10k is waaay too much. Actually it should work WITHOUT pots too....

DId timeline give you guys the pinout info on the LCD? I am pretty sure that all LCD's have different pinout so i hope you are not wiring stuff in wrong pins... or you might fry it.

anyway, post the diagram you are using then I might be able to look it up and compare with my LCD and help out.

SuperMatty · 09-20-2001, 02:53 PM

Miles, it would seem you have a different LCD than I do so therefore I believe your post would be better off in a different thread. The problem with Timeline's Densitron 40x4 LCD, is that there is a ribbon cable pre-wired to the LCD when it is shipped, and the red wire is on the opposite side as pin 1 is labeled on the PCB. Now most of you would probably say 'so just go according to the PCB,' however there was another user about a year ago who posted to this same discussion group saying that the Timeline LCD's pcb is wrong and that infact you need to locate pin 1 according to the red wire on the ribbon cable. In any case, the schematic I am using is this:
http://members.home.net/hardattack/densi.htm

milesg · 09-20-2001, 03:26 PM

SuperMatty, I understand what you're saying, but the pinout sheet that you posted on the the other thread (pinout) is the exact same sheet I got with my LCD, however mine didn't come with a cable, so I didn't think there was anything wrong with the PCB pin numbers.

All I did, was make sure I knew which wires went to the pins as they are numbered on the PCB when I attached my own ribbon cable.

If you look closely at pin 16 on the PCB (as it is marked) you will see that it has NO connection to the rest of the circuits on the board.... it must be pin 16 because there's no connection for pin 16 on the pinout sheet that we have.

Moahdib, Thanks for your help... Supermatty posted the pinout that timeline sent us (the above link)... I believe that Boomin'Volvo used this pinout to create the scheme that we followed.

I hope this gets resolved soon.

-Miles

SuperMatty · 09-20-2001, 03:35 PM

Interestingly enough, I just went to the densitron website and found this...
http://www.densitron.com/display/pdfs/lm4857lv.pdf

Notice the pinout they give in this is completely different than the one timeline sent us. I am going to give it a shot and see where it gets me.

SuperMatty · 09-20-2001, 06:05 PM

GETTING CLOSER!!!!
After rewiring my LCD according to the pin out on my previous post, I found that the 1st and 3rd bars are now lighting up when I turn on the computeR!!! Only problem is, LCDprint detects the LCD is connected and on an ECP printer port, however the output is not showing up...I will continue to work on this.

milesg · 09-20-2001, 06:19 PM

SuperMatty, That's the best news I've heard all day... Do you have any idea what's causing the output to be blank? When you see the two black bars, I believe that it's just waiting for a signal.
So we know that it has power, but apparently nothing else... I hope you've only make a slight mistake with the new re-wiring, and niether of us have actually damaged our screens.

I'm at work right now, so I can't test it out, but I'll see what I can do as soon as I get home.
Thank you.

-Miles

milesg · 09-20-2001, 09:09 PM

okay, here's my plan:

I've looked at the Scheme that Nathan Stuart used to connect the Seiko LCD to the parallel port. All of the pins are labeled and are the same as the pins which are described in the tech sheet directly from Densitron (with the exception of Vdd and Vcc which are both the +5 power supply).

I'm currently re-wiring the LCD following the densitron scheme and making sure that each control line goes to the proper place on the LPT ribbon.

Wish me luck!!!

I'll let you all know how quickly the thing exploded when I'm done

-Miles

SuperMatty · 09-21-2001, 02:18 AM

Welp, reversing the RS and RW pins only made LCdprint stop working properly...so the quest continues...

milesg · 09-21-2001, 02:52 AM

Welp, reversing the +5 and ground pins only made LCD stop working entirely...so the quest continues...

*damn damn damn*

(I can't believe the wires coming out of my keyboard line were +5 [black] and Ground [Red])

Anyway, I think the stupid thing might have been dead before that... If anyone gets it working, I'll try to re-wire it, and it might still be alive, but if not, then I know I can get a new one and make it work.

Sorry SuperMatty, I'm out

Good luck
-Miles