Having trouble to get LMB162ABC to display ANYTHING!

So, I bought this TOPWAY 16x2 lmb162abc(datasheet:https://www.topwaydisplay.com/sites/default/files/2020-02/LMB162ABC.pdf) LCD display. I connected it to my arduino uno with the help of an I2C module. I think it's worth mentioning that i bought this display with this module, i didn't solder it myself. i used the following code.

//Compatible with the Arduino IDE 1.0
//Library version:1.1
#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 16 chars and 2 line display

void setup()
  lcd.init();                      // initialize the lcd 
  // Print a message to the LCD.
  lcd.print("Hello, world!");
  lcd.print("Ywrobot Arduino!");
  lcd.print("Arduino LCM IIC 2004");
  lcd.print("Power By Ec-yuan!");

void loop()

I am pretty sure there is no problem with the soldering or wire connections. But i still don't get it to display anything. Everytime i try to run the code the backlight turns on, but there is no display, not even the boxes of pixels. Is it a faulty display? I tried to run the i2cexpdiag code, but i couldn't find the code or how to run the test anywhere. Also, i do not have any potentiometer. And there are no external resistors in the circuit. Here is an image for further clarification.

If you need any more clarification, feel free to ask. Any help will be appreciated. Thanks!!

I recommend that you run the I2C scanner you have in the arduino examples to make sure your I2C module has the address 0x27.

Yes, i already did that... It showed the address in 0x27.

I would try the hd44780 library. For an I2C LCD display to work, the I2C address and the I2C backpack to LCD pin mapping must be correct. If the library default settings for either or both are not correct the LCD will not work. You can try to figure out the right pin mapping and use an I2C scanner to find the address, but if you install and use the hd44780 library that is done automatically by the library.

The hd44780 library is available through the IDE library manager.

The i2cexpdiag sketch is part of the hd44780 library. Here is the path:

That will tell you if the I2C expander is connected properly, but the library is made for LCDs with the hd44780 controllers. No guarantee that it will work with the S6A0069 controllers on that LCD, but it is worth a try.

@bperrybap might see this thread and can tell you if his library will work for this LCD and if not, what to do.

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I don't find the hd44780 Library in my IDE library manager(IDE version:1.8.16). Do u recommend downloading the zip file and using it?

The best way to install a library is, always, the library manager. Downloading and installing a zip is second best.

Try this: Go to Library Manager (in the IDE menus, Sketch, Include Libraries, Manage Libraries) and in the Topics dropdown choose the Topic, Display, and in the Filter your search box enter hd44780. Select and install the hd44780 library by Bill Perry.

I just checked my installation of the IDE version 1.8.16 and the library is there. Follow the above instruction and scroll down a bit and it is there.

Hey groundfungus, thanks a bunch! I tried the i2cexpdiag code. In the end, backlights were on but there was no display. I think i just need to adjust the contrast pot. But the problem is, i don't have a potentiometer... Is there any way..like using a pull down resistor or something to get around this problem? Do u think it'll be too dangerous to try that?

Just connect pin#3 to GND via a 390R resistor.
That should give a readable display.

Experiment with different resistors from 0R to 680R for best contrast.


Edit: @david_prentice beat me to it, so like he says or,
Use a 100Ω to 1K resistor to ground or if you have no resistor just tie the Vo pin (LCD pin 3) to ground.

Wait a minute. You have an I2C backpack according to the photo. And:

I connected it to my arduino uno with the help of an I2C module.

There should be a contrast pot on the backpack module:

I2C back pack CONTRAST

I'm gonna be honest, i actually thought that it could be the contrast pot, i didn't really know for sure... I'll try to use it then! Thanks again!<3

Hey @groundFungus, if you're still there, i adjusted the contrast pot and now i can the blocks of pixels. But i don't see anything printing whereas it's supposed to be printing hello world!

Hey @groundFungus, thanks a looot for your help! I'm finally able to print things out on my display all thanks to you! I adjusted the contrast and it all worked out! Sorry if i made u feel irritated but i'll remember the time and effort you took to help me!
Thanks again. Have a GREAT day!!

I apologize if I gave any impression of irritation. At no time did I mean to.
Getting LCDs to work can be challenging. Thank goodness for Bill Perry's library. It makes it soooo much easier.

No no i didn't mean it that way..you never showed any irritation at all. I just...thought that i keep asking such dumb questions wasting your time when it was a simple contrast issue. That's all. I'm really thankful and happy.

Partly my bad, I should have thought of contrast earlier.

I do try to be patient. I was a newby at one time, too.

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I have 5 of those type screens and they were all supplied with the pot set for no display, they all took very small adjustment to get readable display
mick in glen innes

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