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Value for money and easy to use, mine had A0 A1 A2 unsoldered, so the address is 0x27, you can solder them to change the address. There are code examples and this device is discussed here: http://arduino-info.wikispaces.com/LCD-Blue-I2C see "I2C LCD DISPLAY VERSION 3"
I used this with a Microchip PIC development board to interface to a 20x4 LCD display. With only 4 wires (including 2 for power) it's simple to set up and uses far fewer ports than the standard LCD parallel interface. As delivered the address pads (A0 A1 and A2) are open but pulled high - so the I2C address is 0x4E. Ports P7,P6,P5,P4 of the PCF8574 interface to DB7,DB6,DB5,DB4 of the LCD Display. Port P3 is hard-wired to the backlight via a transistor: 1 = on / 0 = off. It's great that the backlight can be switched on and off via software with no additional hardware required. Port P2 is the display bit clock : E = 1 -> E = 0 active. Port P1 is R/W hardware Read/Write bit hardware : Read = 1 / Write = 0, so reading from the LCD display is possible, if required. Port P0 is RS Register Select : CmdReg = 0 / DataReg = 1. Display driver is HD44780 compliant. A great buy! I won't be interfacing to an LCD in future without it.
Use the "NewLiquidCrystal" library and connect GND to Ground, VCC to 5v, SDA to Analog pin 4 and SCL to Analog pin 5. Then add "#include " and "LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);" to your code (before void setup). Then, inside void setup add "lcd.begin(20,4);" to your code. To set the cursor position use "lcd.setCursor(X,Y);" where "X" is the column and "Y" is the line. Use "lcd.print();" to write to the display. You should get the display working with this. NOTE: Use the potentiometer on the back to turn the screen contrast down or you might just see white on the screen! Overall a great display that is a lot more useful than a 16x2 size one! My picture is of the display with a test sketch on it showing the possibilites.
Thanks Banggood for the ultra fast delivery again, the package doesn't have any visual damage from transport even though I think that a bit more foam should be added especially with displays to prevent it being damaged in transport is the only thing I recommend, the anti static bag is always a welcome thing to see so kudos for doing that Banggood. I found a little solder bridge between the anode of the display's backlight and ground that I had to clean up before I can use the display, I made a few photos so you can see the solder bridge yourself but it isn't a big deal to me, I just wanted you to know. I'm happy because it feels like Christmas every time I get to open a new package coming from you guys.
The 4 line by 20 char I2C LCD shown in the picture allows you to show diagnostic values or menus / phrases to meet your needs. I had show a smaller 16x2 LCD attached to line follower robot This displayed the reflected lights value as an example. The I2c address was 0x3f.
I have ordered this item on 18 November and received after month (free delivery from China to Hungary). I just have tried to build a small test circuit, based on script of https://diyhacking.com/arduino-lcd-tutorial/ page. Despite my small experience I have succeded it at first probe! (I have changed the text of example and send a Christmas greetings for my friends). So I feel proud :-) and thanks for Banggood for a cheap, but nice blue LCD-screen!
Received the order timely and well packed. Everything works as it should, but you need to fiddle with the code a bit with the Arduino. Blue light is very cool especially during night and low light situations. Characters are clearly readable. Overall a very camper here.
I bought 2 of these, each color one. They're working just fine, nicely built as well. The were very well packed for shipment, see pictures!
The display itself is good. But as with other arduino modules every time you have to explore which library you have to use to get it working properly. Banggood should link the WORKING library direct to the description. Otherwise you have to read many Q&A and reviews to get information about the drivers. Even then you have to try several links and variations of drivers to get the hardware working.
Gostei muito. a entrega foi muito rápida:)