/*************************************************************************

程序說明：

LCD驅動采用4位元（這個4位元方式，在網上搜索來看，還沒有人采用，可以節省4位I/O口），并口方式，晶體4M，注意此LCD有點不同盡量很普通，沒有CS1，CS2頁選擇腳，帶串口方式，型號是TS-12864-3。IC 16F877A。

在屏幕上顯示“Atilla tester"

                     "~_~"

RD7----------LCD D7

RD6-----------LCD D6

RD5-----------LCD D5

RD4-----------LCD D4

RD3-----------LCD E

RD2--------  LCD RS

RD1---------R/W

/***********************程序如下**********************************/

#include "pic.h"

#define lcd_cursor(x) lcd_write(((x)&0x7F)|0x80)//Set the cursor position

#define  LCD_RS RD2
#define  LCD_EN RD3
#define  LCD_RW RD1

#define LCD_STROBE ((LCD_EN = 1),(LCD_EN=0))

void delay_10us(unsigned char x)
{
  while(x--);
}

void delay_ms(unsigned char cnt)
{
    unsigned char i;
do {
  i = 4;
  do {
   delay_10us(39);
  } while(--i);
} while(--cnt);

}

/* write a byte to the LCD in 4 bit mode */

void lcd_write(unsigned char c)
{
PORTD = (PORTD & 0x0F) | (c & 0xF0); //先送高位D7 D6 D5 D4
LCD_STROBE;
PORTD = (PORTD & 0x0F) | (c << 4); //再送低位
LCD_STROBE;
delay_10us(4);
}

/* Clear and home the LCD */

void lcd_clear(void)
{
LCD_RS = 0;
lcd_write(0x1);
delay_ms(2);
}

/* write a string of chars to the LCD */

void lcd_puts(const char * s)
{
LCD_RS = 1; // write characters
while(*s)
  lcd_write(*s++);
}

/* write one character to the LCD */

void lcd_putch(char c)
{
LCD_RS = 1; // write characters
PORTD = (PORTD & 0x0F) | (c & 0xF0); //先送高位
LCD_STROBE;
PORTD = (PORTD & 0x0F) | (c << 4);   //再送低位
LCD_STROBE;
delay_10us(4);
}

/*Go to the specified position*/
void lcd_goto(unsigned char pos)
{
LCD_RS = 0;
lcd_write(0x80+pos);
}

/* initialise the LCD - put into 4 bit mode */
//嚴格按照LCD的復位要求。

void lcd_init(void)
{
LCD_RS = 0;         // write control bytes
delay_ms(40);     // power on delay，wait time>40ms
PORTD = 0x20;     // Function set,set 4 bit mode
LCD_STROBE;
delay_10us(10);     //wait time >100us
    lcd_write(0x20); // Function set:4 bit mode.
    delay_10us(10);     //wait time >100us
lcd_write(0x0C); // display ON/OFF control.
    delay_10us(10);     //wait time >100us
    lcd_write(0x01); // display clear
    delay_ms(10);       //wait time >10ms
lcd_write(0x06); // entry mode set
}

void main(void)

{
   TRISD=0X00;
   PORTD=0X00;
   lcd_init();
   lcd_goto(0x00);
   lcd_puts("Atilla tester");
   lcd_goto(0x11);
   lcd_puts("~_~");
   while(1);
}