20x4 LCD only shows zeros

I have an Arduino UNO, and a green 4x20 LCD, model TS2040-1. I followed this tutorial:

And only changed the size of the LCD in the code.

But LCD only shows two rows of zeros. I shared a photo of it here:

The LCD is healthy. I was created a LCD2USB project with this LCD and it's fine. I tried to use other part of the breadboard to ensure it doesn't have any disconnected wires. But it still the same.

Can you help me please? What can I check?
thanks in advance.

You have the wiring exactly wrong. LCD pin 1 is near the edge of the pc board.


Thank for the quick answer (:

It doesn't appear right in the photo. First and last pins are connected to the ground.

First and last pins are connected to the ground.

That will happen even when the wiring is backwards. The tipoff is the potentiometer. You have it's wiper connected to pin 14, not to pin 3.


Oh! WIring was in reverse order!
Thanks for mentioning it.

There's a map of pins on the back of the LCD. But it's in the reverse order! I wasn't noticed that.
Now it works fine.