The 16 x 2 LCD that I have interfaced with arduino uno is not working. The light shows but then black grids appear on it.
I've been facing this issue for the past 1 week. I'll be grateful if someone helps!
P.S. Yes I've done and rechecked the connections. and also have searched multiple times on various forums.
I've attached the connection between arduino and the LCD. Any kind of help appreciated.
Thankyou in advance.
I haven't used potentiometer though.
codegirl21:
I haven't used potentiometer though.
Then don't expect it to work. 
If you don't have a potentiometer, then connect pin 3 to ground with a 330 Ohm resistor.
If you use a potentiometer, do not connect it to 5 V - Vcc.
Of course you also need code to be loaded to the Arduino for this to work.
Since you have not mentioned code, or posted it according to the instructions for posting questions, I naturally presume you have no code.
I note from the Fritzing wiring picture that the backlight illumination led receives 5V. This may damage the display. Please place a 220 ohm resistor in the 5V wire to pin nr. 15 ('A') of the LCD display
A quick image search with Google reveals that her main problem stems from the fact that she is relying on an Instructable as her source.
As you can infer by the connections the LCD contrast is being provided by PWM, and the code reveals that this is the case. I did not notice any mention of the possible need to to adjust the output which is most likely incorrect for this particular display.
LCD_code.ino:
#include <LiquidCrystal.h>
int Contrast=75;
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup()
{
analogWrite(6,Contrast);
lcd.begin(16, 2);
}
void loop()
{
lcd.setCursor(0, 0);
lcd.print("Only Innovative");
lcd.setCursor(0, 1);
lcd.print("Subscribe");
}
Paul's suggestion to connect pin 3 of the LCD to GND will determine if this is the only problem.
@Codegirl21 - disconnect the blue wire from Digital pin 6 and connect it to GND.
As far as the backlight goes we can hope that there is a current limiting resistor on the pc board. Connecting the 220 ohm resistor as suggested above would be good insurance if that is not the case.
Don
I just realized that there is another problem that will show up as soon the contrast is fixed.
There should either be a considerable delay added to loop() or, since the text is not changing, all of the code that is in loop() should really be in setup() and loop() should be empty.
Don
photoncatcher:
I note from the Fritzing wiring picture that the backlight illumination led receives 5V. This may damage the display.
Extremely unlikely if this is one of the common, almost universal "1602" displays.
If resistor "R8" is "101" - 100 Ohms, then the illumination LED will be drawing about 25 mA. You do not need any series resistor - unless of course, the display is too bright for you!
Zoom
Sometimes R9.
floresta:
Paul's suggestion to connect pin 3 of the LCD to GND will determine if this is the only problem.
@Codegirl21 - disconnect the blue wire from Digital pin 6 and connect it to GND.
Actually, with display pin 3 connected to Arduino pin 6, the correct way to make the code work is to use
digitalWrite(6,LOW); // somewhat superfluous
pinMode(6,OUTPUT);
No adjustment is either necessary nor in any way useful - you are using pin 6 as a dumb 40 Ohm resistor - that is all this arrangement ever does.