USING LCD
The LiquidCrystal library allows you to control LCD displays that are compatible with the Hitachi HD44780 driver. There are many of them out there, and you can usually tell them by the 16-pin interface.
The LCDs have a parallel interface, meaning that the microcontroller has to manipulate several interface pins at once to control the display. The interface consists of the following pins:
A register select (RS) pin that controls where in the LCD's memory you're writing data to. You can select either the data register, which holds what goes on the screen, or an instruction register, which is where the LCD's controller looks for instructions on what to do next.
A Read/Write (R/W) pin that selects reading mode or writing mode
An Enable pin that enables writing to the registers
8 data pins (D0 -D7). The states of these pins (high or low) are the bits that you're writing to a register when you write, or the values you're reading when you read.
There's also a display constrast pin (Vo), power supply pins (+5V and Gnd) and LED Backlight (Bklt+ and BKlt-) pins that you can use to power the LCD, control the display contrast, and turn on and off the LED backlight, respectively.
The process of controlling the display involves putting the data that form the image of what you want to display into the data registers, then putting instructions in the instruction register. The LiquidCrystal Library simplifies this for you so you don't need to know the low-level instructions.
The LCDs can be controlled in two modes: 4-bit or 8-bit. The 4-bit mode requires seven I/O pins from the Arduino, while the 8-bit mode requires 11 pins. For displaying text on the screen, you can do most everything in 4-bit mode, so example shows how to control a 2x16 LCD in 4-bit mode.
THINGS NEED IN THIS PROJECT :-
- Arduino or Genuino Board
- LCD Screen
- pin headers to solder to the LCD display pins
- 10k ohm potentiometer
- 220 ohm resistor
- JUMPER WIRES
- breadboard
Before wiring the LCD screen to your Arduino or Genuino board we suggest to solder a pin header strip to the 14 (or 16) pin count connector of the LCD screen, as you can see in the image above.
To wire your LCD screen to your board, connect the following pins:
- LCD RS pin to digital pin 12
- LCD Enable pin to digital pin 11
- LCD D4 pin to digital pin 5
- LCD D5 pin to digital pin 4
- LCD D6 pin to digital pin 3
- LCD D7 pin to digital pin 2
CIRCUIT DIAGRAM:-
CODE :
// include the library code:
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup() {
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// Print a message to the LCD.
lcd.print("hello, world!");
}
void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print(millis() / 1000);
}
EXPLANATION
The lcd.begin(16,2) command set up the LCD number of columns and rows. For example, if you have an LCD with 20 columns and 4 rows (20x4) you will have to change this to lcd.begin(20x4).
The lcd.print("--message--") command print a message to first column and row of lcd display. The "message" must have maximum length equal to lcd columns number. For example, for 16 columns display max length is equal with 16 and for 20 columns display max length is equal with 20.
The lcd.setCursor(0,1) command will set cursor to first column of second row. If you have an LCD 20x4 and you want to print a message to column five and third row you have to use: lcd.setCursor(4,2).
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