LCD I2C Not Displaying Text Blocks or Text

Other Hardware Displays
1

I have these 2 LCD i2Cs for a school project and I'm just doing some quick tests to make sure they work and I can use them, but I've encountered some problems.
My set up is a 3rd party Arduino Mega 2560 (an Osoyoo Mega 2560), the LCD I2C, and I'm drawing power from the data cable connected to my laptop if that helps. I know the wiring is correct, I've checked my work on multiple sites.

What's happening is when everything is wired up and the data cable is plugged in, the LCD turns on, but it is just a blank blue screen. The text boxes are missing entirely, but the red power light is on. For testing purposes I was using the sample Hello World code from the LiquidCrystal_I2C.h library and when I uploaded that code, the LCD remained blank, but turned off for a second before coming back on.

I know the address of the LCD is 0x27, I ran that address scanning program multiple times just to be sure. I even set the address as 0x3F to see if that would help. I have a second LCD I2C as well and I tried that one and the same exact thing happened. Both LCDs came in the same 2 pack if that helps.

2

You should find a (blue?) potentiometer on your backback - adjust it till you see boxes in the first row only.

If you still can't get it working:
post a clear picture showing your mega, the lcd backback, the LCD and each and every connection you have made.

We must be able to identify both sides of each single wire where it is connected to.

If you need more pictures to present everything - post more pictures.

post the output of the i2c-scanner.

3

noiasca:
You should find a (blue?) potentiometer on your backpack - adjust it till you see boxes in the first row only.

Not quite! :astonished:

First - and as always, with the power off - disconnect the SDA and SCL to the I2C backpack. Power it up - the backlight probably will go on but whether or not it does, adjust the blue (usually) potentiometer until you see the "blocks" on the first line.

Then with the power off, reconnect SDA and SCL and see how you go. :grinning:

4

Yeah, that did the trick. The blocks are appearing and text is printing now. Thank you so much!