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

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.

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.

This works great with the i2clibraries.i2c_lcd class in Python. I tried it on 3.3v, but it needs the 5v. The backlight comes with a jumper cap, but I swapped it for a 10k pot, so now I have brightness control as well (see pic). And, its bigger than you expect, especially after using tiny oleds.

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.

Display works. Sometimes. It will go from being perfectly readable to blackboxes and gibberish simply by looking at the display for too long. Contrast potentiometer does not stay set somehow. Spend the extra $4 to get a similar display from a better seller.

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

Display worked as expected. I had trouble initially setting up in code as I have only used 2x20s in the past. I sent an email to HiLetgo and they responded with all the info I needed. I highly recommend.

The display arrived in a padded envelope but well protected by several layers of bubble wrap. Internet searching for 20x4 LCD Arduino I2C provided code for testing and hookup data. I used the newest library for LCD display on my Arduino: LiquidCrystal_I2C. My display had an I2C address of x3F. If yours doesnt just google I2C address sniffer for an app that will ferret out your LCDs address. Nice clean product that works fine-- word of advice.. if no display results be sure and adjust the pot on the back of the unit, also I had to put in a jumper on the back I2C board to get the backlight. Ordered 7/26/18 got it 7/30/18 - over a weekend!

Shipped fast, next day in my case, was package in its own box making it very well protected. I was able to hook it up a have some examples running on it in minutes! This will be perfect for a Time. Temp, Pressure display project in my shop! The extra two lines this display provides may come in very handy for this!

I2C is the way to go to minimize the pin count used on your board. Love the contrast Black on Yellow display very bright and very easy to read, The Contrast control works great. Price point is about right for this product and Yes I will purchase more the next time I need more displays .