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

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 wouldnt 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!

I bought this display to use in a GPS clock that displays local time and date and UTC time and date. Here are my observations. 1. Its big! I should have read the specs more closely, but its much bigger than I expected. 2. The contrast is OK, but its nothing to write home about. 3. The viewing angle is very small. Once you get about 30-degrees off-axis, the contrast falls off rapidly. You have to be almost dead in front of the display to read it. 4. The default brightness of the backlight is very bright - too bright for me - harsh even. It lights up a room at night. I added a 330-ohm resistor to tone it down a bit. Otherwise, its a standard LCD display, and writing code for it is pretty simple. For what its worth, the hd44780.h display library is MUCH faster than other libraries (such as LiquidCrystal_I2C.h). I highly recommend it. I am undecided if I will use this display in my project. The viewing angle is just so small, and thats not great for a clock. A TFT display can be had for about the same price, and the viewing quality and versatility are much better. That being the case, I would not recommend this display.

Worked as expected.

As an I2C device this was a no brainer and didnt consume any pins on my Arduino since the I2C bus is shared with several other devices. Once you adjust the potentiometer for the brightness it is very nice to read. It needs a different library than its 16x2 cousin but that was a breeze to find and install.

Follow Up: I just received the 2nd screen that I ordered to replace the broken one. This one is defective as well. This time it is detected on the I2C bus 1/5th of the time if that, and when sending data to it it similarly only works a small percentage of the time. Most of the time is doesnt respond at all - just the white blocks on 2nd and 4th rows. I should mention that I2C sensors and an OLED screen on the same I2C bus (same pins, wires) work 100% of the time. Will not be buying screens from HiLetGo anymore. Go with another brand for a few dollars more. Did not work. I scanned all I2C addresses and it did not show up at all - tried different wires, different spots on breadboard, etc to no avail. I also tried sending data to the two addresses suggested by others - but nothing happened. All it would do when connected to power is show the backlight and two rows (row 2 and 4) of white blocks. Contract adjustment did not help.

great buy

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; didt 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.

These are nice display modules with 2 wire I2c interface. Display is sharp and bright. Easy to read with or without the backlight. I tried to get a picture but my phone camera did not do it justice.

I much prefer these green LCD displays with the yellow backlight because I can read them with the backlight off which saves about 40+ ma. Some of the projects put the Arduino to sleep as I am trying to minimize power draw. The blue LCDs are not really readable when the backlight is off.

No issues with this. Using it with Arduino Uno. Almost plug and play.