iic i2c 1602 lcd module blue screen library files quotation

The Arduino control board has 20 10 ports, add some sensors, SD cards, etc., and the relay module has more than 10 ports. The original 1602 screen needs 7 10 ports to be driven.

For me the whole LCD library stuff seems to be some kind of a mess, as everybody who is able (or not) to write a library names it as he wants. Thus I assume that a lot of users who don"t pay attention (albeit of all the warnings/instructions here) how many different LCD library stuff lies around in folders Arduino IDE has access to and you can"t always predict what the compiler"s mood is to pick this or that library as long as the names are all the same.
although i double checked that I had deleted (and emptied the bin) all older LCD libraries and ran a search through my whole system for all "LCD.." stuff - my Arduino IDE told me something about an update for some libraries including a LCD I2c library (it mentioned Robert(?) Schwartz library - don"t remember exactly anymore).
After a few days getting this reminder I finally accepted the update procedure although I was very suspicious about the result - Bingo: after that my workaround test sketch didn"t work any more (Compiler error). So I deleted the updated folder, re-installed the New_LiquidCrystal 1.3.4 library again: voilà: my workaround worked.
So my question: do you or somebody here have an idea how that update showed up although I had deleted all the LCD library stuff other than Malpartida"s New Liquid Library ??

For an I2C LCD display to work, the I2C address and the I2C backpack to LCD pin mapping must be correct. If the library default settings for either or both are not correct the LCD will not work. You can try to figure out the right pin mapping and use an I2C scanner to find the address, but if you install and use the hd44780 library that is done automatically by the library.
Install the hd44780 library. The hd44780 library is the best available for I2C LCDs. The library is available in the Library Manager. Go to Library Manager (in the IDE, Sketch, Include Libraries, Manage Libraries) and in the Topics dropdown choose Display and in the Filter your search box enter hd44780. Select and install the hd44780 library by Bill Perry.
The class that you want to use is the hd44780_I2Cexp class. There are examples to show how to use the library. The nice thing about the hd44780 library is that it will autodetect the I2C address and the I2C backpack to LCD pin mapping.
Also there is the contrast adjustment, usually a small blue trimpot on the I2C expander backpack. If that is not adjusted properly the display will show nothing or just boxes.

The CFA533-***-KC series is a 16x2 I2C LCD with keypad. The I2C interface allows you to use just two lines (SDA & SCL) to have bi-directional communication with the I2C LCD. Other devices can also share those two I2C control lines with the LCD. Only 4 wires are needed to connect this I2C LCD: power, ground, SDA (I2C Serial DAta) and SCL (I2C Serial CLock).
The CFA533 can run on 3.3v to 5.0v directly, with no changes needed, so you do not need to do any level translation between your embedded processor and the I2C LCD. Simply power the CFA533 from the same supply as your processor and the I2C signal levels will match up.
Using only one address on your I2C bus, you can add all the elements that you need for your front panel. The CFA533 I2C LCD can also read up to 32 DS18B20 digital temperature sensors, giving you an easy way to integrate temperature sensing over the I2C bus. No additional firmware or pins are needed on the host system.
This CFA533-TFH variant features crisp dark letters against a white, backlit background. The keypad has a matching white LED backlight. Since the LCD is a backlit positive FSTN, the CFA533-TFH I2C LCD is readable in direct sunlight, as well as complete darkness.

What is the purpose of declaring LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE); if we are using pins A4 and A5? I know that 0x27 is the ic address but what is the rest for?
I am getting a error while i m going to add zip file of lcd library error id this zip file does not contains a valid library please help me to resolve this issue as soon as possible.....
Hey guys. My LCD works fine using the above instructions (when replacing the existing LCD library in the Arduino directory) but I can"t get the backlight to ever switch off. Suggestions?

ERM1602SBS-2.1 is 16 characters wide,2 rows character lcd module,SPLC780C controller (Industry-standard HD44780 compatible controller),6800 4/8-bit parallel interface,single led backlight with white color included can be dimmed easily with a resistor or PWM,stn- blue lcd negative,white text on the blue color,wide operating temperature range,rohs compliant,built in character set supports English/Japanese text, see the SPLC780C datasheet for the full character set. It"s optional for pin header connection,5V or 3.3V power supply and I2C adapter board for arduino.

As we all know, though LCD and some other displays greatly enrich the man-machine interaction, they share a common weakness. When they are connected to a controller, multiple IOs will be occupied of the controller which has no so many outer ports. Also it restricts other functions of the controller. Therefore, LCD1602 with an I2C bus is developed to solve the problem.
I2C bus is a type of serial bus invented by PHLIPS. It is a high performance serial bus which has bus ruling and high or low speed device synchronization function required by multiple-host system. The blue potentiometer on the I2C LCD1602 (see the figure below) is used to adjust the backlight for better display. I²C uses only two bidirectional open-drain lines, Serial Data Line (SDA) and Serial Clock Line (SCL), pulled up with resistors. Typical voltages used are +5 V or +3.3 V although systems with other voltages are permitted.
Step 3:Since in some code, the libraries needed are not included in Arduino, so you need to add them before compiling. Unzip the downloaded file. Copy the folders under the Library folder to the libraries folder in Arduino (if you cannot find the path in Arduino, open Arduino IDE, click File ->Preferences, and you can see the path in the Browse box, as shown in the following diagram). Compile the program.

During this second week with Ian we learned how to use libraries and displays on Arduino. First of all Ian gived us two documents to install, one was the library and the other one was the code.
I don’t know why on my computer the code wasn’t working, so i just tried to install another LiquidCrystal_I2C.h library and i changed the code by myself, then i added the library to the Arduino environment.
Ms.Josey
Ms.Josey