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

Hello friend, I should say that I am quite new here.
I am trying to display the “hello world” characters on my LCD display ( Model: "Displaytech 202B).
I am following the codes below that are given as example on arduino sketch. I have wired up my ardino-LCD exactly as it is instructing on the sketch.

But, after running the code, my LCD doesn’t get the power and it doesn’t do anything actually. Where is my fault?
The code I am trying to execute:

/*
  LiquidCrystal Library - Hello World
 
 Demonstrates the use a 16x2 LCD display.  The LiquidCrystal
 library works with all LCD displays that are compatible with the 
 Hitachi HD44780 driver. There are many of them out there, and you
 can usually tell them by the 16-pin interface.
 
 This sketch prints "Hello World!" to the LCD
 and shows the time.
 
  The circuit:
 * LCD RS pin to digital pin 12
 * LCD Enable pin to digital pin 11
 * LCD D4 pin to digital pin 5
 * LCD D5 pin to digital pin 4
 * LCD D6 pin to digital pin 3
 * LCD D7 pin to digital pin 2
 * LCD R/W pin to ground
 * 10K resistor:
 * ends to +5V and ground
 * wiper to LCD VO pin (pin 3)
 
 Library originally added 18 Apr 2008
 by David A. Mellis
 library modified 5 Jul 2009
 by Limor Fried (http://www.ladyada.net)
 example added 9 Jul 2009
 by Tom Igoe
 modified 22 Nov 2010
 by Tom Igoe
 
 This example code is in the public domain.

 http://www.arduino.cc/en/Tutorial/LiquidCrystal
 */

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis()/1000);
}

As I can guess that I am missing something here (in the code below): I don’t understand the instruction here. (Note: I haven’t used any resistor and potentiometer and I don’t know what is “wiper”)

 * 10K resistor:
 * ends to +5V and ground
 * wiper to LCD VO pin (pin 3)

The picture of my wiring up is attached here.

Your wiring is incorrect. Read this:

http://arduino.cc/en/Tutorial/LiquidCrystal

The Vo pin controls the LCD contrast, and must be hooked up with a potentiometer as per the wiring diagram.

Reading the tutorial is a good starting point. In the tutorial's schematic, they don't show power being supplied to the LED backlight.

MANY people have had problems starting with LCDs. Don (aka FLoestra) has often posted his checklist to getting an LCD working. One thread you can find it in is http://forum.arduino.cc/index.php?topic=152265.0 Item #1 in his checklist addresses the backlight.

@arduinodlb, thanks a lot for your quick response! So, is there any alternative way of using potentiometer? I mean if I am not intended to use the potentiometer, what else could it be done? Another thing, do you observe any other mistake in my wirings? Anyway, tomorrow I should buy a potentiometer and let's see... $)

For now, you could probably put two 5K-ish resistors in series between 5V and ground, and take the middle of that voltage divider to Vo. Your contrast will not be variable, but it will set it to the middle which hopefully, is readable.

Ideally, if your LCD has a backlight, you should wire that up too.

You have been asking a question about this display before.
That was answered (by me).
And i told you how to wire this display, as found in the datasheet:

me:
Page 7 of that datasheet shows the pin numbers, and they are off standard.
From left to right, viewing from the display side with the contacts at the bottom, you’ll have pin 14, 13,- - - pin 1, pin 15, pin 16.
Pins 15 is backlight + and pin 16 is backlight -.

You disregarded this, looking at your photograph.

I also told you that pulling the contrast pin down to GND will probably result in a usable display and leaving it open is will result in an illegible display, so you decided to leave it open.

@MAS3,To be honest ,I am very glad when I see that you really have a good intention to help me again. 8) I feel sorry if u feel that I disagree with u. In reality, I never disagree. :) . Basically, I don't get the word "off standard", what is that? However, I have looked the data sheet so many times and I found that the pin starts from left (doesn't it?). I couldn't grasp the whole instruction you gave me. That time, I had a very simple question, "At which side the pin starts from in my displaytech?"

OK, three things missing here, and in order of priority:

1} Light it up. Pin 1 is in fact, the one near to the end of the board. Pin 16 then should be connected to ground on the Arduino, and pin 15 to Vcc (5V) through a 100 ohm resistor as the specification sheet is a bit confused as to whether this resistor is actually provided on the LCD board in this model.

Unless it is lit up, you simply will not be able to see what you are doing.

2} Set the contrast voltage. A 10k potentiometer with ground and +5V at the ends and the wiper connected to pin 3 is usual, but you should get a "good enough" approximation with a 1k resistor from ground (pin 1) to pin 3 and a 10k resistor from pin 3 to Vcc (pin 2). Without this correct voltage connected you will get nothing on the display at any time.

3} The Read/ ~Write line - pin 5 - must be connected to ground. You appear to have it connected to pin 11 on the Arduino bit it should be pin 6 on the LCD to pin 11 on the Arduino.

I think if you correct all these problems, it is most likely to work.

jabirfatah91:
Basically, I don’t get the word “off standard”, what is that?
However, I have looked the data sheet so many times and I found that the pin starts from left (doesn’t it?).
I couldn’t grasp the whole instruction you gave me. That time, I had a very simple question, “At which side the pin starts from in my displaytech?”

By off standard, i mean it is not like most LCD modules.
Those modules have pin one at the left hand side, second from left is number two and the last or most right is pin 16.
This module is different, so no, pin one is not at the most left side.
Paul__B seems to disagree with me too, he refers to the datasheet and tells uspin 1 is at the end of the board, which reads to me like left hand side.
The datasheet he refers to, had the attached picture on page 2, click on the attached picture to see it full size.
Directly below that picture in the datasheet is a chart telling what each pin number’s function is.
These functions are directly compatible with other modules, again their location on the module is not.

If this is not clear enough, i’m sorry i don’t know how to make this any clearer.

MAS3: This module is different, so no, pin one is not at the most left side. Paul__B seems to disagree with me too, he refers to the datasheet and tells us pin 1 is at the end of the board, which reads to me like left hand side. The datasheet he refers to, had the attached picture on page 2, click on the attached picture to see it full size.

You are dead right (and as clear as you could be; I cannot disagree) - I didn't look at the datasheet that closely (magnified) to notice the totally bizarre pin designations (and I clearly did not read your pin explanations either).

One simply does not expect that sort of thing.

So it appears that he does have to do all the things I suggested (by pin number), but according to the peculiar pin numbering, including reconnecting the four data pins to suit..

@MAS3 , now your explanation makes a lot of sense. I have done my wiring exactly as it supposed to be (according to the data sheet pin formate and the tutorial: http://arduino.cc/en/uploads/Tutorial/LCD_bb.png).
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, niether it displays any text. Is there anything wrong with my LCD?

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.