My LCD (16x2) lights up but doesn't print anything! not even black boxes on the top!

Other Hardware Displays
1 
int rs = 7, en = 8, d4 = 9, d5 = 10, d6 = 11, d7 = 12, readPin = A2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

void setup() {
  // put your setup code here, to run once:
  lcd.begin(16, 2);
  //16 columns, 2 rows
  pinMode(readPin,INPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  lcd.setCursor(0, 1);
  lcd.print("Hello World");
  lcd.print(millis()/1000);
  Serial.println(analogRead(readPin));
}

Hey genuises, I've been trying to make this simple LCD screen circuit that displays "Hello World".
I have made my connections as per :

image
image1024×903 75 KB

I have triple-checked the connections and have even dismantled and reconnected everything twice. I have tried seeing other solutions on this forum too, but nothing seems to help.

My soldering of the headpins on the LCD also seems fine.

I have already tried the following:

  1. Disconnecting all data pins connecting only the power pins to get a row of black boxes on the top.
  2. Adjusting the potentiometer.
  3. Connecting both ends of the potentiometer to GND, as suggested by someone on some other forum thread.
  4. Checking if my potentiometer is defective. I disconnected everything and performed an analogRead on the potentiometer(as shown in the code), and the potentiometer correctly varies from 0 to 1023 on turning its wheel.

None of these have helped. Since the lights are turning on, I don't think there's a problem with the LCD either. Can anyone please help me out?

PS: I'm a CS student so all this is a bit new for me :sweat_smile:

2

EDIT2: You appear to be missing 4 data lines.
EDIT: OOPS, just noticed you don't have the I2C daughter board.
In that case, I can't remember how to do it the old way.

First I would use the LiquidCrystal_I2C library, that way there is only 2 wires (SDA, SCL) plus power. Also make sure the backlight is jumpered at the back/side and when "Hello World" is supposed to be on the screen, adjust the small pot to adjust the backlight.

3

Hello haardshah234

Post a picture of the hardware used.

4

Hey, I'm actually following a tutorial from a YouTuber (not any random one, he's a really good youtuber) and I'm doing just as he is and he is the one who designed the circuit he got it right. I didn't see any comments complaining about this issue so it's definitely an issue on my side. I don't have an I2c daughter board, and I don't even want to buy one just yet, I want to learn how stuff goes like this ('the old way' as you mention).

And by adjusting the backlight are you implying that the brightness of the LCD changes when the potentiometer is turned?
Coz that's NOT happening with me. The brightness of the screen is constant throughout the potentiometer's range. Also, I forgot to mention that I also tried putting a resistor on the 15th(BLA) pin in series to the 5V, (as shown in the circuit diagram of the LCD Hello World sample program on Arduino's official website) and doing that reduced the brightness of the 'backlight' meaning that my LCD is capable of doing that too, but isn't doing it for some reason.

5

In that case, check this guys work. I am a member there and Bill is very good. I think there is a difference in your wiring and Bill's but I am having trouble (autistic 82yo) rotating the diagrams in my head.
LINK

6

17215913674792297373055774140938
172159136747922973730557741409381920×1440 152 KB

17215914330992672741938296593|666x500
17215914768615221592217070347251
172159147686152215922170703472511920×2560 125 KB

17215915082823458223600878545908
172159150828234582236008785459081920×2560 97.5 KB

I hope these are sufficient. (Please check the soldering too, I'm a beginner at soldering)

The wiring follows tge same colour scheme as in the circuit diagram, except the orange in diagram is replaced with a yellow wore and the yellow in diagram is replaced with a white wire.

I can snap more pictures if you want me to.

7

The circuit diagram on that website is exactly the same as mine.

Also, I'm assuming the 82yo part was sarcasm? :thinking:

8

That soldering will not do at all.

Fix that, add the #include <LiquidCrystal.h> line to the top of your sketch as shown below, and it'll work.

#include <LiquidCrystal.h>

int rs = 7, en = 8, d4 = 9, d5 = 10, d6 = 11, d7 = 12, readPin = A2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

void setup() {
  // put your setup code here, to run once:
  lcd.begin(16, 2);
  //16 columns, 2 rows
  pinMode(readPin,INPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  lcd.setCursor(0, 1);
  lcd.print("Hello World");
  lcd.print(millis()/1000);
  Serial.println(analogRead(readPin));
}

lcd

9

The backlight pot seems to have an extra wire. The blue wire on the left. The pot should ony have G 5V on the outside pins, and the wiper connects to the BRIGHT pin, 3rd from the left I think.

10

I do have #include <LiquidCrystal.h> in my code, it didn't get selected when I was copying the code ig, sorry for that :sweat:

11

Then once you fix that soldering you should be fine, if you've wired it up as that Fritzing diagram and my photo show.

12

The blue wire on the potentiometer is not extra. It is coming from an Analog pin which I've used to perform analogRead to check if the potentiometer is working correctly or not.

13

My wires are following this circuit diagram. I will try to re-solder it tomorrow

14

+1

This isn't good:

Screenshot_20240721-211332-037
Screenshot_20240721-211332-037360×1688 257 KB

Compare the solder joints with @van_der_decken 's image:

Screenshot_20240721-211535-082
Screenshot_20240721-211535-0821068×420 295 KB

That's what you should aim for.

Soldering_Results

1 Like
15

Once you confirm the POT is working, remove the bluw wire in case it is having some side effect.
NOTE: Unless you just happen to have one of the two good brands of bread board, they are famous for bad connections. wiggle all the wires to check. The pictures are not good enough to truly tell, but the wiring seems to be right.

16

Thanks for this, but before I soldered the head pins, I just connected the wires and the LCD Screen and this problem was still there. The display would only glow up on a certain angle (with just the blank blue screen) and that's when I realised that I had to solder the head pins. The problem of the lcd glowing only when held at a certain angle was fixed, but the screen is still blank, so I think the soldering is not an issue. Tomorrow I'll try to change the position of the lcd and try again, though I don't think my bread board is of bad quality. I'm sorry for everything here, I'm just a beginner, I wrote my first Arduino code not less than a week ago!

17

Not at all, I was born 1942. Played with my first computer in high school 1959, it was analogue machine for student experiments donated by Ferranti Packard Canada.

1 Like
18

Make sure the +ve and -ve bus are continuous from one end to the other. Some boards are only continuous 1/2 the way. Ask me how I know.

19

Yes, no surprise.

Because all your solder joints are so perfectly uniform?

You asked:

Why did you ask that if you didn't suspect the soldering may be a problem?

20

Hi, @haardshah234
Welcome to the forum.

image
image1135×633 37.5 KB

You will need to fix your soldering first.
It looks like not enough heat and not long enough application of the soldering iron to let the solder flow.

Tom... :smiley: :+1: :coffee: :australia: