LCD problem(different from all the others)

Hi everybody, this is my first time posting here because I really can't solve this LCD problem. I have read many other topics on here but I can't find an answer to my problem. So here it goes, like many others my lcd is not working. I followed many tutorials and I'm 100000% sure that the problem is not in wiring or in the code. I know that for sure because the LCD used to work, I got it running and it showed all I wanted it to. The problem started when I didnt use it for about a week, I came back to show it to a friend and the LCD showed 2 rows of white squares(not one like in other posts). The connections are all soldered and they are all in the right places(see pics), the pins are pushed in the breadboard all the way, same for the arduino pins(all triple checked), Im also using a 10k pot wired the right way, checked 10 times (tried with a 2k too and it worked at first, but it stopped too). The lcd always sits in the garage at 70 degrees, so I doubt its weather related. The power source is my laptop(i also added an extra 220 ohm resistor like it says in the tutorial). After trying to fix the LED(I switched laptop batteries, tried a 9v, tried a 12v, tried different wiring and different wires, tired without pot) I finally tried the LCD tutorial on here and the backlight came on(didnt even know it had one), but no words on it, only 2 rows of white boxes. I very slowly turned the pot and still white boxes. After all the trials the LCD died completely, no more lights, boxes or anything, tried to wire it to power only but wont give signs of life. Did I forget anything from the other posts? Could the LED be defective(I got a cheap one from ebay, came without data sheet and the ebay page does not have one either)?

Btw no pics of code because I literally copied the one on the arduino tutorial(Ive checked and rechecked every letter, even deleted it and pasted it from the website)

This is the circuit image, it didnt let me upload it my original post, please do not delete.

circuit picture [MERGED] image for previous post - Displays - Arduino Forum

Donsa's picture:

Your soldering needs to be improved. Tutorials and videos on the internet.

The pot is not connected to either GND or VCC.
You only need to connect the GND pin. Adjust pot for contrast.

Quite honestly, you should get a readable display if you just connect VO pin to GND with a plain wire.

David.

I guess it's time for me to re-introduce my generic step-by-step approach for checking out your LCD.

(1) If the module has a backlight then get it working properly. This involves only pins 15 and 16 on most LCD modules. Make sure to use a current limiting resistor if there is none on the LCD module.

(2) Get the power and contrast working properly. This involves only pins 1, 2, and 3 on most LCD modules. You should be able to just barely see blocks on one row of a two row display and on two rows of a four row display.

NOTE: The Arduino has not been used yet, except as a possible source for the power needed for the first two steps. Do not try to go any further until this is working. If you don't see the blocks then no amount of program code will help.

(3) Connect the LCD R/W pin (pin 5) to GND.

(4) Connect the six control and data wires between your LCD module and your Arduino. Make sure that your wiring matches the numbers in the descriptor (or vice versa).

//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
  LiquidCrystal lcd( 7, 8,  9, 10, 11, 12);      // put your pin numbers here

(5) Upload your sketch and it should work.

For troubleshooting a 'static' sketch, one that displays a simple message or two and then stops is recommended. All of your code should be in setup(), and loop() should be empty between the brackets.

#include <LiquidCrystal.h>

//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
  LiquidCrystal lcd( 7, 8,  9, 10, 11, 12);      // put your pin numbers here

void setup()
  {
  lcd.begin(16, 2);                              // put your LCD parameters here
  lcd.print("hello, world!");
  lcd.setCursor(0,1);
  lcd.print("it works!");
  }

void loop()
  {
  }

NOTE: Don't forget to check out the continuity on those jumper wires that you are using. From what I have read they are sometimes found to be intermittent or open.

Don

Donsa:
I followed many tutorials and I'm 100000% sure that the problem is not in wiring or in the code.

In about 9 years of seeing people having issues connecting their hd44780 lcd to an arduino I think I can count the times it wasn't wiring on two hands.
In those cases it was usually obvious as the pixels were screwed up. In a few cases the LCD was very old and was too slow for the code.
In all other cases it was wiring issues even when the user was extremely confident it wasn't.
In a few cases it was wired correctly at the time, but previous mis-wiring fried the LCD.

There can be different types of wiring issues, including:

  • bad wires
  • bad connections in breadboards
  • incorrect use of the breadboad
  • bad connections in the Arduino headers
  • bad solder joints
  • missing wires
  • incorrect wiring (perhaps the wiring does not match the sketch pin mappings)

Since you didn't show us the code you are using or provide a link to it, we cannot verify that you are wiring up your connections to match the code.

So, as David pointed out, at this point from the information you have provided so far, all we can say is your pot is not wired up correctly and you may have some soldering issues.
(so much for the 100000% certainty that there isn't a wiring issue... :wink: )

--- bill

Hey thanks to all for your replies they have been super useful. Yeah maybe not 100000% sure haha and for the pot, it was actually wired in the old pic but i got frustrated with the circuit and disassembled it so when reattaching everything together for the new pic, i forgot those 2 wires ;). Anyways the backlight tutorial was enough to discover that it was actually a bad lcd, cus it only shows fragmented words and some of the white blocks dont have some white lines in them (probably i connected the lcd wrong at some point and fried it). Waiting for a new lcd now. Thanks again guys!

Incorrect wiring or wiring issues can cause some really crazy things to show up on the display, including things that sound similar to what you are describing.
Unfortunately, we can't see what you are seeing to be able to verify your diagnosis.

--- bill