Hi,
I need a library for i2c communication of LCD. I am already using a library but now only half of the screen is seen. The other half is ignored and full of full squares. LCD is 4x20.
Don't know which one you have but the initializing usually requires that you tell it it's 4,20 instead of the default 2,20. If you don't then you get only the top two lines. The example code should say something about this.
I did. Even used i2c scanner for address.
Don't know what else to add other than read the examples closely for clues.
Good luck.
First things first: have you looked at the datasheet of your LCD? It generally reports the pins settings that can slightly differ from model to model.
Second: there is an I2CLCDguesser.ino that you may run to discover its configuration here
HTH
Strange problem... I too faced some issues with a 4 x 20 display and found some good advice in these fairly recent (April 2015) instructions from Mark VandeWettering at
http://brainwagon.org/2015/04/22/using-a-sainsmart-lcd-panel-with-the-arduino-1-6-3-ide/
Good Luck!