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My LCD does not work. Help please.

J

jnex26

2[H]4U
Joined
Aug 7, 2001
Messages
3,353
OK I've bought a 2x24 LCD with a hd44780a00 controller. with 8 Bit connections.


http:\\www.btinternet.com\~jnex\DATA.pdf

Now I'm on my second one of these displays and I just can't get it to display anything on the screen Even On Powerup. I've double check the wiring and i've put in the varible resistor for the contrast. and I've tryed diffrent peices of software but no matter what i try It does not work. I've tryed diffrent Modes in the Bios. But still nothing.

Any Suggestions ?
 
Can you post the wiring diagram you used so we can get an idea of what you're working with? One thing that happens is people accidently mix up the pins on the parallel port connector, usually they're printed on the connector, so you might double check that you're using the correct pins, same goes for the lcd end.

Also you may want to check for bad solder joints, they'll be dull in apperance whereas good joints should be shiny.

And I fixed your link for you http://www.btinternet.com/~jnex/DATA.pdf
 
Sorry Let me expand on this

LCD.gif


That's the Schmatic

The DB25 Plug was wired up correctly According to the numbered pins.

This is how it was wired up

LCD.jpg


The Power was from a Molex and I added a resistor (100R) In the + Line to protect the LCD the Fed voltage is 5.01 Volts.

Also should it matter that I'm not powering the EL backlight.

Also I have tryed just Powering the LCD to get the test screen Which does not happen. But the Chip does not get hot then
 
According to the data sheet, Pin 1 is ground and pin 2 is +5v, other than that the 2nd picture seems to match the data sheet. Other than that, might be a bad display.

Also where'd you buy it, I'm interested in getting a new display, I've got at 16x2, but I'd like a 20x4.
 
Originally posted by rm.o
According to the data sheet, Pin 1 is ground and pin 2 is +5v, other than that the 2nd picture seems to match the data sheet. Other than that, might be a bad display.

Also where'd you buy it, I'm interested in getting a new display, I've got at 16x2, but I'd like a 20x4.
Click to expand...

Well These displays are actaully a 24x2 I'm getting them from EBAY but this is my second display i've had from him. Is there a way i can test them by just supplying the power first or somthing before hooking them up to see if they are working ?
 
OK looking even closer at the specs of this datasheet it does not even seem to be the right one !!! SO I've attached some images of the thing could we identify this please becuase I Beleive that the Pin-out on this are not the same as the datasheet. Also the Datasheet is for a 20x2 and this is a 24x2 and This has a EL backlight the other does not have any backlight.

LCD1.jpg

LCD2.jpg

LCD3.jpg

LCD4.jpg

LCD5.jpg


I've got Two more of these on order if i can get the next one working without a problem then I'm willing to give the spare one away to the person that been the most helpfull in solving my dilemma.
 
You can use the hd44780 datasheet, and look at the pinout and trace the connections to the 14 pin header on your lcd. If you look at page 5 of the data sheet you see the connections, RS and R/W and such should match up with the schematic you provided earlier. As far as the EL backlight is concerned, you may need an inverter, I'm not sure as I've never used an LCD with an EL backlight.
 
Thanks for posting the Datasheet That helped idetify the pin that are problems and also itentify that i've got a broken trace. so this one is junk

the pinout seems to be right. HOWEVER it seems that these are Standard Japaneese Fonts and not Standard english fonts. does that make a diffrence ?
 
the font language does not matter because the LCD software is what controls which pixels are shaded and which aren't.

If you are getting junk when running and LCD program, then the baud rate is probably off.
 
Originally posted by ness1469
the font language does not matter because the LCD software is what controls which pixels are shaded and which aren't.

If you are getting junk when running and LCD program, then the baud rate is probably off.
Click to expand...


WHAT? hes not using a graphical LCD, its a character. the characters it displays are BUILT IN so it sure as hell DOES matter what language its in!
 
If you're fairly handy with a soldering iron you can fix the broken trace, just get a really thin wire, or a single strand from a larger wire, scratch the green coating of both sides of the trace and solder the wire in between. It's not easy if you don't know what you're doing, but it can be done.

As for the character sets, it does matter that it's japanese, but it should still display something when you hook it up, it'll just be japanese.
 
Originally posted by rm.o
If you're fairly handy with a soldering iron you can fix the broken trace, just get a really thin wire, or a single strand from a larger wire, scratch the green coating of both sides of the trace and solder the wire in between. It's not easy if you don't know what you're doing, but it can be done.

As for the character sets, it does matter that it's japanese, but it should still display something when you hook it up, it'll just be japanese.
Click to expand...

I can't Even Get the to display the black bars on power up
 
I stumbled across this datasheet for a 2x16 lcd using the hd44780a00 chip, you may want to look it over.

The pinout is on page two. It's different than the other pinouts I've seen, so maybe it matches your lcd.
 
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