"Hello world" is not displaying on LCD; Even my LCD doesn't get power.

jabirfatah91: But I am still not getting anything on the LCD display (except the first two row lit up; as you can see on the picture). There is no contrast and brightness on my display, neither it displays any text. Is there anything wrong with my LCD?

That's actually different from where you started. Originally, you said the display did nothing. Now it is displaying some, albeit incorrect, things. You need to make sure you give us accurate information as we move forward, or else we diagnose the wrong problem. The picture is definitely useful.

That's actually different from where you started. Originally, you said the display did nothing. Now it is displaying some, albeit incorrect, things. You need to make sure you give us accurate information as we move forward, or else we diagnose the wrong problem. The picture is definitely useful.

Could you please tell me what else info you need in order to move forward? I will be happy to come back with that. However, this time my connection is exactly the same as you see the picture below. http://arduino.cc/en/uploads/Tutorial/LCD_bb.png

Do you want that I upload a clearer version of my wiring picture here again?

To my eyes, that's now starting to look like a broken display. The fact that it's displaying something, but nothing sensible is not a good sign.

Let's see what other people think.

Your wiring doesn’t look correct to me.

Please check your wiring and make sure it matches the tutorial image you’re attached,

At the very least, it doesn’t look like Gnd, Vcc and Vo are correctly wired. They should be going to the LCD pins 1,2 and 3. It looks like you skipped a pin in the middle.

You may have known (by reading the previous threads) that my LCD module is strange. The pin serialization is not standard here (with this displaytech 202B).
The left most pin is 14 and the right most pin is 16. From the right most side 3rd and 4th pins are respectively 1 and 2 (ground and 5v). if u have a look on the data sheet.

Displaytech 202B details.pdf (459 KB)

After writing that, I understood your wiring and removed the post. I was hoping before you replied :)

I wired everything once again, but it is behaving still in the same way. No light on the display, only the first row is lit up (if u have a closer look on my LCD, u will see).

As I say, it's starting to look like a broken display to me.

Let's see what others think.

So, now I am nearly successful! arduinodlb, was right, my LCD was broken (since I got it from school lab and many use that uncarefully)
I bought a new LCD and wired that up. It’s able to print out the “hello, world”. But, there is a very simple problem. If you see the characters very carefully that every single letter is missing a segment. As an example, if we see the letter “h”, there is a missing portion at the verticle line. And the whole “hello, world” line is not completely clear.
WHat I guess that is it has something to do with changing contrast with potentiometer. But, i tried by changing the contrast. It doesn’t make the texts very perfect.
Do you think that adding a resistor can solve the issue?

I am sure it will not.

You have placed your display on top of the breadboard, and put some jumper wires through the holes of the module into the breadboard. The breadboard is kind of spring loaded so the wires will make contact to the breadboard. Your display is not spring loaded and i'm sure there is no stable contact there. Solder pins to the module , and after that put those pins in the breadboard. Connect the wires to the corresponding breadboard contacts. You might consider soldering the wires directly to the display too, but that way you loose some jumper wires for your next project.

By the way, the photo's aren't clear enough to be sure, but it looks to me like you didn't wire the backlight LEDs. That doesn't tell anything about the wrong or absent characters, but it's for sure why reading then display was hard.

Sorry, but that's another bad LCD.

There's really nothing you can do wrong that would result in missing pixels in your LCD display. I'd try another one again.

I disagree here (sorry). First thing you can do wrong is what happened here: Throw some wires in the direction you think they belong and hope it will work. It will not, or with very strange errors. Take a look at the last photograph. There's a lot of space between the jumper wires and the holes in the module's PCB. This is a guarantee for huge problems, and i'm confident that that is what leads to the strange performance of the LCD. What if the contrast pin (3) is very noisy because of a very poor contact ?

Admittedly, those wires to the lcd don't look like they're soldered.

You have to solder wires that aren't on the breadboard, otherwise you have random electrical connection.

What I see in the most recent photo is that the instructions in the LiquidCrystal tutorial given in reply #1 were not followed. If you look on the LiquidCrystal tutorial page:

Before wiring the LCD screen to your Arduino we suggest to solder a pin header strip to the 14 (or 16) pin count connector of the LCD screen, as you can see in the image above.

Simply put: Wires not soldered to LCD module == Poor electrical Connections. Poor electrical connections == Things may or may not work correctly.

As far as the missing pixels go, it looks like it could be loose connections to the actual LCD glass on the elastomeric connector. http://en.wikipedia.org/wiki/Elastomeric_connector If you press on the LCD does it change or get better? If so, you could try twisting the tabs on the back of the module that hold the frame. Twist them just a bit to tighten them - normally clockwise - and see if it helps.

--- bill

jabirfatah91: I wired everything once again, but it is behaving still in the same way. No light on the display, only the first row is lit up (if u have a closer look on my LCD, u will see).

In the "broken" LCD photo in this reponse: http://forum.arduino.cc/index.php?topic=206035.msg1517558#msg1517558

I see what looks a LCD that is wired up incorrectly or not completely wired up. From the datasheet diagram, the pin order is:

14, 13, 12, 11, 10, 9, 8, 7. 6, 5, 4, 3, 2, 1, 15, 16

Looks to me like: It is hard to tell exactly how it is wired due to some parallax issues. But for sure there is only 1 set of power connections vs the 2 needed. and then the r/w line (LCD pin 5) does not appear to be wired up.

From the photo I can't tell if the backlight is not wired up or if all the control lines are shifted over by 2 pins.

Either way, the way that is wired up, it isn't going to work and you may not see anything if the backlight power connections are not hooked up.

You need to wire up the backlight power to turn on the backlight to be able to see the pixels on that display.

NOTE: You may need to use a resistor on the backlight. I'd use like a 100 to 330 ohm resistor to be safe.

--- bill

The most recent photo shows that the backlight is now wired up and operating.

Unfortunately, the sporadic missing pixels cannot relate to poor data and control connections to the module, but more likely to the internal “Zebra connector” as observed by bperrybap. It may be possible to “fiddle” the LCD assembly to fix this (at the most extreme, undo the tabs, disassemble and reassemble the LCD panel).

Given the problems with making less than positive connections, it is possible that the previous display would work if everything was connected suitably, but this unfortunately seems to have been anything but a straightforward exercise. :smiley:

Admittedly, those wires to the lcd don't look like they're soldered.

You have to solder wires that aren't on the breadboard, otherwise you have random electrical connection.

And off course, I must admit it that the pins were not soldered with the module and that causes some disappeared pixels on the display. There is no doubt that it's just because of that. Moreover the current flow becomes random because of that. I, however, feel that this issue can be fixed by later by soldering. At least I am satisfied that this time my connection walks on the right way.

Well, you definitely have to solder those connections.

After you've done that, get back to us with what's happening.

Paul__B: The most recent photo shows that the backlight is now wired up and operating.

From what I can see, there are two differenct LCDs being used. The "new" one uses the more typical pinout and that one has the backlight hooked up and seems to be working other than the pixel issues - which is not going to be fixed by soldering.

The "original" one in this response: http://forum.arduino.cc/index.php?topic=206035.msg1517558#msg1517558 which was said to be "broken"/"damaged"/"bad" is the one I'm seeing wiring issues.

That one looks like the backlight is not hooked up. (probably needs a resistor to limit the current) It also looks like the r/w line is not hooked up either.

--- bill

As I previously stated, I believe both LCDs are broken. Get another one, and use solder.

arduinodlb: As I previously stated, I believe both LCDs are broken. Get another one, and use solder.

I saw what appeared to be wiring errors in the photo of the first LCD in this post: http://forum.arduino.cc/index.php?topic=206035.msg1517558#msg1517558

Are you saying you wired it up differently than the photo you showed us?

Or are you saying that the backlight is wired up and that the r/w signal on LCD pin 5 is hooked to ground and we just can't see it in the photo?

I don't see the backlight power signals and the ground signal for R/W in that photo.

--- bill