HiLetgo 2004 20X4 LCD Display Screen Serial with I2C Adapter - Yellow Green Color LCD for Arduino Raspberry Pi

I use the 4-line x 20 character displays in all my projects. I have switched to I2C units exclusively and pay little attention to color. They are great to work with.

Was a little skeptical having read some reviews regarding poor solder connections, especially as the pictured device in the product description clearly shows solder bridges on the I.C. so I inspected it very carefully before proceeding. Workmanship as good as other quality and expensive components. Everything worked as advertised. The LED jumper disables the back-light and the display contrast is very clear. I also ordered the 2 extra I2C boards from the same vendor (Hiletgo) and both tested perfectly. Same results on other devices from them.

I was skeptical that a yellow backlit LCD would be visually appealing, but the contrast between the yellow background and the black letters is the best I have seen of any other color combination. It is amazingly clear and bright. The unit I received has an I2C address of 0x27 just like the product description states. The LiquidCrystal_I2C and LiquidCrystal_PCF8574 libraries from GitHub both work equally well with this unit, so you can use either one. HOWEVER, both libraries turn the backlight off by default so having the backlight jumper on the I2C interface isn't enough, you must ALSO use lcd.setBacklight(1) in your program to activate the backlight.

You need female to male cables to hook it to the Arduino board. It powered up fine and shows the 4 lines you see in the picture of the product. However, I can not get it to write to line 4 ; lines 1,2,3 work fine but anything to line 4 over writes the data on line 2 ?????One day later and nothing will display; but the backlight is on and rows 1 and 3 have dark cursors in every column. Adjusting the POT does nothing.Got a replacement unit and it does the same thing; did't even show the original splash screen. Someone else had this same problem with two units. Arduino board works fine with the 16x2 screen that came with the kit. I give up.

Great product and works as designed. One screen came with a loose connection on the contrast potentiometer. At first one of the screens would not display the text and after looking into it I could get the I2C address but it wouldn't display any text. The green back light was fine and after testing the contrast pot I found that it was soldered enough, so I added solder and it works great now. Good price!