LCD always gives black boxes..

Using Arduino Displays
1

Hello my friends,

I am in last step of my project. I passed all steps with your helps and again I want it.

So you can understand from topic that I have a LCD display problem.
LCD gives black boxes like picture below.

I tried to write something simply, but I couldnt

My connections:

LCD Pin -----> Arduino
LCD pin 14 --> pin 1
LCD pin 13 --> pin 2
LCD pin 12 --> pin 3
LCD pin 11 --> pin 4
LCD pin 10, 9, 8, 7 --> empty
LCD pin 6 --> pin 5
LCD pin 5 --> GND
LCD pin 4 --> pin 6
LCD pin 3 --> GND
LCD pin 2 --> 5V
LCD pin 1 --> GND

Here is my LCD 's datasheet : http://www.ozkulelektronik.com/p_docs/HY-1602F-001.pdf

AND

My simple codes for trying

#include <LiquidCrystal.h>

LiquidCrystal lcd(6,5,4,3,2,1);

void setup(){
lcd.begin(16,2);
lcd.print("Hello");
}

void loop(){
  
lcd.print("hello");
}
2

Your display is not being properly initialized.

Your photograph is not quite good enough to let us check your connections. We need to be able to see both ends of every wire.

It would help if the focus were sharper as well. Your soldering looks suspicious but I really can't tell.

Your program code, as simple as it is, is not correct either. You do not want to write data that does not change in loop(). For now just remove everything between the brackets in loop().

You really should stay away from pin 1 (as well as pin 0) as it is used by the serial connection. It is possible that your code is not being downloaded properly.

Don

3

Pin-3 is incorrect. That is the CONTRAST PIN.
It should NOT be shorted to GND.
It should be connected to the wiper of a 10k or higher pot which has the other two terminals connected to +5V and GND respectively.
It should be adjusted for a voltage of about 0.45Vdc on pin-3.
You cannot expect to be able to use the lcd until this corrected.
Also , you have not connected your backlight pins 15 & 16. Read the datasheet you posted. You can connect pin 15 to +5V with an 82 ohm resistor.
Gnd pin 16.

4

Those are good points but they both can be taken care of after he gets the display functioning.

Many displays work acceptably with pin 3 grounded and his appears to be one of them. The blocks are darker than optimal but the text should still be usable. If the other row of blocks were visible I would say that he really needed a potentiometer.

Many displays work acceptably without a backlight and his appears to be one of them. The blue displays with white letters are the ones that really need a backlight to be usable.

Don

5

I also tried with potantiometer. But It just adjusted of black boxes visibility. I wish I take a photo for all connections but breadboard so crowded and complex. I mean it s hard to understand whick wire goes where :slight_smile:

I tried it without pin 1, but it didn't work again. I checked all connection again and again. Everything looks like ok. I will check them again. So is it normal that black boxes appearing on lcd display?

6

Try rewiring it like this tutorial.
You shouldn't be using pin-1 for anything because that's your serial port Tx pin

7

So is it normal that black boxes appearing on lcd display?

Yes and no.

The presence of the boxes means that you have the power and contrast voltages applied properly. The fact that the potentiometer adjusted the visibility of the boxes means that it is working properly.

The fact that there are boxes on the display instead of text means that the LCD controller is not properly initialized as I mentioned before. This could be due to bad wiring or the absence of the proper program code.

Here are several things to try:

  • Rework your solder joints.
  • Rewire the six lines between the Arduino and the LCD making sure to avoid digital pins 0 and 1.
  • Make sure that your constructor data (the six numbers in parentheses) match your wiring.
  • Make sure that LCD pin 5 is connected to GND.
  • Make sure that loop() is empty for now.

Don

8

Hello,

I made some triyng but still I couldn't get display.

  • Rework your solder joints.

I checked all of them and make them again.

  • Rewire the six lines between the Arduino and the LCD making sure to avoid digital pins 0 and 1.

I used tutorial pin and codes and rewired everything then again wire and check lot of time.

  • Make sure that your constructor data (the six numbers in parentheses) match your wiring.

I am sure about it

  • Make sure that LCD pin 5 is connected to GND.

Yes it's connected to GND.

  • Make sure that loop() is empty for now.

and I made loop() empty but Still I have blackboxes :S

9

It's time for a new photograph.

Don

10

You must not use the port pins denoted "0-RX" or "1-TX" on the Arduino so the descriptor in your code which appears as LiquidCrystal lcd(6,5,4,3,2,1); should not have the number 1 in it. This single mistake will prevent any such sketch from working.

You must re-wire it and adjust your sketch to match.

11

You must not use the port pins denoted "0-RX" or "1-TX" on the Arduino ...

As I mentioned in the very first reply it is not a good idea to use those pins but "must not use" is overkill. If you are out of available pins you can frequently use pins 0 and 1, depending on what you are trying to use them for.

In this case I am pretty sure the LCD will work (if all the other problems are resolved) if you disconnect it while downloading the code and then reconnect it afterwards.

Don

12

Hi
I am having the same problem, I have no potentiometer but
as i read before you can use an resistor in my case is 2X650 ohm resistors.
The program is uploaded successfully in the arduino uno but I can't manage
to have no text in screen.
I am new to arduino and would appreciate anyone help.

regards,

lcd.jpg
lcd.jpg3264×2448 1.56 MB

13

@hamitrs

You have your resistors connected in series between pin 3 and GND which seems to be working for you but will be no better than connecting pin 3 to GND for many displays.

I would suggest that you start by redoing your soldering. You are using too much solder and may have bridged (connected) some of the pins.

Don

14

Hi floresta,

Thank you for your reply!
It turns out your right, the only problem was there was not to much solder but
in the pins D4-D7 not solder right, I did it once again and now everything
works perfectly fine.

Thank you very much to your reply and your help!

15

agreed. that soldering looks horrendous. Wick off the solder and this time let the pin heat up for a second or two before appying the solder. It should flow smoothly and be shiny when done. Use a meter to ohm out between the pads to verify there are no shorts after resoldering.

16

floresta:
As I mentioned in the very first reply it is not a good idea to use those pins but "must not use" is overkill. If you are out of available pins you can frequently use pins 0 and 1, depending on what you are trying to use them for.

In this context, I think it is entirely appropriate advice for a novice. Even questions such as "out of available pins" most frequently flags some misunderstanding such as that the "analog" pins are not in fact, primarily digital pins just as the others.

Using all of the available pins frequently serves as a warning that they are not being used to advantage, and that a rethink of design is in order, such as use of shift registers, or a MAX7219 as a matrix driver - particularly if they are being used to drive LEDs directly as this risks overloading the chip.

Not to mention the value of using the serial functions as a debugging aid, or an essential interface in the current or extended design.

17

I am super sonic stupid person :)) I have spare time just today and I try again solve to LCD problem. I was order new LCD and some parts. Then I read some point from book and I saw I forget wiring R/W to GND.. It's completely lack of atteintion :slight_smile: Thank you again for your helps..

18

Then I read some point from book and I saw I forget wiring R/W to GND.

How do you account for this exchange way back in replies #5 and 6?

  • Make sure that LCD pin 5 is connected to GND.

Yes it's connected to GND.

Don

19