Project Description:-

  In this project we are going to learn various things about this chip set and displaying text on this LCD. The HD44780 16x2 char LCD screen Use 4 bit parallel interface with backlight.

This Primary Objective in this project are:-

1.  Displaying  "Hello Word!! LCD " message on the scree.
2.   Interfacing The LCD to the Microcontroller Using  4 Bit Mode.
3.  Generating and Displaying Custom Char on the LCD Screen. click here for custom char


Operation 
   
      as i have mentioned  before this type of lcd are connected to microcontroller using parallel 8bit or 4bit lines.
using 8 bit method is quite simple but take 8 lines (for data or command)+ 3 control signal total 11 line , i guess few small microcontrollers don't even have that much of I/O lines ,so in 4 bit mode total 7 lines (sometimes 6 ) are required .  in this tutorial i will show you with both of the methods .

Pin description

PIN NUMBER	SYMBOL	FUNCTION
1	Vss	GND
2	Vdd	+ 3V or + 5V
3	Vo	Contrast Adjustment
4	RS	H/L Register Select Signal
5	R/W	H/L Read/Write Signal
6	E	H → L Enable Signal
7	DB0	H/L Data Bus Line
8	DB1	H/L Data Bus Line
9	DB2	H/L Data Bus Line
10	DB3	H/L Data Bus Line
11	DB4	H/L Data Bus Line
12	DB5	H/L Data Bus Line
13	DB6	H/L Data Bus Line
14	DB7	H/L Data Bus Line
15	A/Vee	+ 3.5V for LED/Negative Voltage Output
16	K	K Power Supply for B/L (OV)

in 8 bit mode all the Data line DB0 to DB7 are being used for transferring the the data to lcd but in 4-bit mode only 4 line form DB4 to DB7 are being used to transfer the  8 bit wide data in two peaces one after another .

we can't display any data on the lcd until all the required internal command register of the lcd are not being properly initialized.
to know every thing about this lcd controller .. you can go through it's data sheet
click here to download HD44780 data sheet
so now we will learn how to initialize the lcd.