THEORY:
Liquid crystal display (LCD):
A display that consists of two polarizing transparent panels and a liquid crystal surface
sandwiched in between. An electric current passed through the liquid causes the crystal to align so that
light cannot pass through them. The LCD has ability to display numbers, characters and graphics. A
sample photo of the LCD module is shown in Figure.
LCD Pin Description:
2. Data register
The RS pin is used for selection of this registers. If RS = 0, Instruction command code register is selected, allowing the user to send a command. If RS= 1 the data register is
selected, allowing the user to send data to be displayed on the LCD.
R/W (Read/ Write):
R/W input allows the user to write information to the LCD or write information from it.
R/W = 1 ; When reading
R/W = 0 ; When Writing
E (Enable):
The enable pin is used by the LCD to latch information presented to its data pins.When data is supplied to data pins, a high to low pulse must be applied to this pin in order for the LCD to latch in the data present at the data pins. This pulse must be a minimum of 450 ns wide.
D0 – D7 (Data pins):
The 8 bit data pins, D0 – D7, are used to send information to the LCD or read the contents of the
LCD‟s internal registers.
Program code
#include <lpc214x.h>
void delay_ms(unsigned char time)
{
unsigned int i, j;
for (j=0; j<time; j++)
for(i=0; i<8002; i++);
}
void LCD_command(unsigned char command)
{
IOCLR0 = 0xFF<<16; // Clear LCD Data lines
IOCLR1=1<<16; // RS=0 for command
IOCLR1=1<<17; // RW=0 for write
IOSET0=command<<16; // put command on data line
IOSET1=(1<<18); // en=1
delay_ms(10) ; // delay
IOCLR1=(1<<18); // en=0
}
LCD_data(unsigned char data)
{
IOCLR0 = 0xFF<<16; // Clear LCD Data lines
IOSET1=1<<16; // RS=1 for data
IOCLR1=1<<17; // RW=0 for write
IOSET0= data<<16; // put command on data line
IOSET1=(1<<18); //en=1
delay_ms(10) ; //delay
IOCLR1=(1<<18); //en=0
}
LCD_init()
{
LCD_command(0x38); //8bit mode and 5x8 dotes (function set)
delay_ms(10) ; // delay
LCD_command(0x0c); //display on, cursor off, cursor char blinking off(display on/off)
delay_ms(10) ; // delay
LCD_command(0x06); //cursor increament and display shift(entry mode set)
delay_ms(10) ; // delay
LCD_command(0x01); //clear lcd(clear command)
delay_ms(10) ; // delay
LCD_command(0x80); //set cursor to 0th location 1st lne
}
LCD_write_string(unsigned char *string)
{
while(*string) //Check for End of String
LCD_data(*string++); //sending data on LCD byte by byte
}
int main(void)
{
PINSEL1 = 0x00; //Configure PORT0 as GPIO
PINSEL2 = 0X00; //Configure PORT1 as GPIO
IODIR1= 0x07<<16; //Configure P1.18, P1.17, P1.16 as output
IODIR0= 0xFF<<16; //Configure P0.23 - P0.16 as output
LCD_init(); //Initialize LCD 16x2
LCD_write_string("Trendy Coding");
LCD_command(0xc0);//second line
LCD_write_string("Subscribe it");
while (1);
}
Circuit diagram
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