LCD shows black rectangular boxes in second line

Using Arduino Displays
1

I have read othr forum, related to same problem. I tried to rectify as much as I could but it shows the same problem.
I have connected the data lines t0 9 , 10 ,11 ,12 and i have connected RS pin to 6 and enable to 5 of arduino.
R/W (pin 5) is connected to ground. I have changed the lcd too, but it just shows the same problem. I have checked the soldering. I am sending the schematic.

#include <LiquidCrystal.h>

LiquidCrystal lcd(6, 5, 9, 10, 11, 12);

void setup() {
 delay(1000);

 lcd.begin(16, 2);
 
lcd.clear();

lcd.setCursor(0,0);

 lcd.print("hello, world!");
}

void loop() {
 lcd.setCursor(0, 1);
 
 lcd.print(millis()/1000);
}

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2

We cannot tell by the image where your wires go.
Your back-light looks "really really" bright, your LCD may need a series resistor, otherwise you may ruin the LED.
Also, back off on the contrast to the point where the black boxes just disappear.

3

In your future projects, you really do not need to update your LCD any faster than every 200-500mS as there is significant screen lag time.

4

Right, first things first.

Go and read the instructions, then go back and modify your post to mark up the code as such so we can examine it comfortably and reliably.

The apparent backlight brightness is just a camera artefact. In any case check that on the LCD module, either resistor R8 or R9 is 100 ohms - marked "101".

The blocks are on the first line of the LCD, not the second. You have it upside down.

5

I have modified the code in the proper format. I checked my lcd module , i did not see ''101'' written anywhere. So I have connected 10k resistor on pin 15 of LCD. I have tried working my code again but still I am not getting any result.

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6

Sorry - attachments are broken on the "forum" at present. Need to re-link them to see. :grin:

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That's funny - two copies of the same picture!

Anyway, I cannot fault the wiring as best I can see it. Did you look to see what was specifically written on the little black resistors "R8" and "R9" (on the back of the board)? I'll bet one was "101", 10K will be too dim for the display, 270 ohms would be fine - but if you can read the "101", you do not need it at all.

Look, I suggest you pull off all the wires going to Arduino pins and test them for continuity (or swap each with the wire that takes 5V to the LED in the LCD and see if it still lights up). Dud (Chinese) wires are not entirely uncommon. The code is clearly not getting through to the LCD module at all though we know it is getting power, and if the code is correct, the wiring must be faulty.

Oh, and your "loop" should be:

void loop() {
 lcd.setCursor(0, 1);
 lcd.print(millis()/1000);
 delay(250);
}
7

Thank you so much for helping out. Yep, it was one data wire not working, i checked it using LED as it was suggested.
Now LCD is working!

8

Congratulations.