Hey there.I need some help in my project. This is my first project with 16x2 lcd screen which I have connected with arduino uno.All the wiring is done correctly as has been told in the arduino>file>examples>liquid crystal>helloworld.I have uploaded the same code without any change but the only thing which is being shown on the lcd screen is solid blocks.Please somone help me I have read many related articles but cant figure out whats wrong.
If you followed the wiring then you should have a potentiometer to adjust the contrast for the LCD. You need to adjust the contract so that you can just see the blocks when the display is cleared and then drop it just below that threshold.
Thanks for the reply.But i have already connected potentiometer. Can't actually figure out whats wrong .I have attached the photos.
No photos were attached.
So I am not clear - if you have installed the pot then have you used it to adjust the display? That's what it's for.
I have adjusted the pot a lot many times but either it shows blocks else nothing.
I'll like to share one thing more.I have tried with all codes given in official website of arduino with same wiring ( all codes of liquid crystal ) but all showing the same problem.The pot meter is all right i have tried it with analog and controlling the brightness of a led.
You have obviously gotten the power and the potentiometer (pins 1,2,3 15, and 16) connected correctly.
Until we see a photo of your actual connections and a copy/paste version of your actual code there is not much more that we can do.
Don
/*
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
- LCD VSS pin to ground
- LCD VCC pin to 5V
- 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.
*/
// 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);
}
Well there is your problem. You are trying to get a cartoon drawing to work.... 
Note: seeing a cartoon drawing of how you intended to wire things up is no good.
As don said:
floresta:
Until we see a photo of your actual connections ... there is not much more that we can do.Don
--- bill
Image size is too large .I am not able to post it.!
Sir,
Maybe you need to check the interface assignment of LCD module, sometime the same 16X2 module has different interface assignment.
Image size is too large .I am not able to post it.!
(1) Make it smaller.
or
(2) Post it somewhere that will accept large images and post a link here.
Don
https://drive.google.com/file/d/0B-uozw6XsukkWGdCMzhNQVZmOHM/view?usp=drivesdk
https://drive.google.com/file/d/0B-uozw6XsukkV1N5N05VT3BJcEk/view?usp=drivesdk
https://drive.google.com/file/d/0B-uozw6Xsukka1kxellvdl9Ya2s/view?usp=drivesdk
https://drive.google.com/file/d/0B-uozw6XsukkWXpLTXdRbmg2aHc/view?usp=drivesdk
Now i am facing another problem after few days as it happened two weeks before that my arduino is not able to connect with my pc .what is surprising is that sometimes it connects while sometimes not.
I used the same code and board to test 20X4 LCD module and it works good!!
None of those photos allow us to unambiguously follow each wire from the LCD back to the Arduino. We have to be able to do that in order to verify your wiring.
You should also check the continuity of each of those jumper wires, especially if they are inexpensive imports.
Don
Malti,
You need to show the EXACT wiring you are actually using.
And do not change it or modify it after you show the wiring you are using.
The wiring in photo 20170409_120347.jpg does not appear to match the others.
For sure the wiring in 20170409_120347.jpg does not match the wiring in 20170412_082933.jpg
The colors of the wires being used are different and while the backlight and some pixels appear to be on in photo x347.jpg there are no visible connections to either the backlight anode or cathode.
Therefore these photos of are completely different wiring.
Details matter.
In cases like this where the LCD is not working, it is a wiring issue.
In order to get help, you must show how the LCD is ACTUALLY wired up and show it in a way that allows other to visually inspect all the wiring to look for issues.
--- bill
Malti:
Now i am facing another problem after few days as it happened two weeks before that my arduino is not able to connect with my pc .what is surprising is that sometimes it connects while sometimes not.
Different problem, start a different thread.
--- bill
I am sorry for that .
But i didn't actually remember that i took these photos on different occasions since i changed the wiring every time.what i mean by this is that the code remained the same as well as the connections but the only thing that changed was the color of the wires aince every time I faced this problem i thought that there is some mistake in the way i am connecting.
And in some photos where the blocks are being showned is where the lcd screen is showing aomething else it shows nothing.