LCD 8 bit

#include

#define RS P3_0
#define RW P3_1 //RW=0 => ghi
#define EN P3_2 //RW=1 => doc
//RS=0 => code
//RS=1 => data
#define LCD_PORT P1

void delay_5ms(){
int i,j;
for(i=0;i<250;i++)
for(j=0;j<4;j++){}
}

void delay_15ms(){
int i,j;
for(i=0;i<250;i++)
for(j=0;j<100;j++){}
}
void LCDWriteCmd(unsigned char c)
{
RS=0;
RW=0;
LCD_PORT=c;
EN=1;
EN=0;
delay_5ms();
}

void LCDWriteData(unsigned char c)
{
RS=1;
RW=0;
LCD_PORT=c;
EN=1;
EN=0;
delay_5ms();
}

void LCD_init()
{
delay_15ms();
LCDWriteCmd(0x30);
LCDWriteCmd(0x30);
LCDWriteCmd(0x30);

LCDWriteCmd(0x38);
LCDWriteCmd(0x0C);
// LCDWriteCmd(0x06);
LCDWriteCmd(0x01); // Xoa man hinh LCD
}

void LCD_clear()
{
LCDWriteCmd(0x01);
}

void LCD_home()
{
LCDWriteCmd(0x80);
}

void LCD_putstr(unsigned char *s)
{
while (*s)
{
LCDWriteData(*s);
s++;
}
}

void main()
{

LCD_init();
LCDWriteCmd(0x01);
LCDWriteCmd(0x80);
LCDWriteData('A');
LCDWriteData('B');
LCDWriteData('C');
LCDWriteData('D');

LCDWriteCmd(0xC0);
LCD_putstr("dien-dien tu");
while (1) {}
}

Bạn có thể nói được nguyên lý hoạt động của việc hiển thị LCD ko ? Thank !