//帶中文字庫的12864LCD顯示程序
#include <reg52.H>
#include <intrins.H>

#define uchar unsigned char
#define uint unsigned int

//SCM12864-05端口定義
#define LCD_DATA P2 //數據口
sbit RS = P0^5; //并行的指令/數據選擇信號, H數據, L命令
sbit RW = P0^6; //并行讀寫選擇信號, H讀, L寫
sbit E = P0^7; //并行使能端, H有效, L無效
//sbit PSB = P3^7; //并/串接口選擇, H并,L串
//sbit RET = P3^3; //復位, L有效

uchar code datas1[] = {"廣州大學"};
uchar code datas2[] = {"物理與電子工程學院"};
uchar code datas3[] = {"電子（3）班"};
uchar code datas4[] = {"565839485@qq.com"};

//延時約2us
void delayUs()
{
    _nop_();_nop_();    _nop_();_nop_(); _nop_();_nop_(); _nop_();_nop_();
}
//延時 a * 1ms
void delayMs(uint a)
{
    uint i, j;
    for(i = a; i > 0; i--)
        for(j = 100; j > 0; j--);
}

//檢測LCD是否處于忙狀態, 若忙返回1, 空閑返回0
bit checkBusy()
{
    bit busy;
    RS = 0;
    RW = 1;
    E = 1;
    delayUs();
    busy = (bit)(LCD_DATA&0x80);
    E = 0;
    return busy;
}

//等待LCD到空閑
void wait()
{
    while(checkBusy());
}

//寫命令
void writeCmd(uchar cmd)
{
    wait();
    RS = 0;
    RW = 0;
    E = 0;
    delayUs();
    LCD_DATA = cmd;
    delayUs();
    E = 1;
    delayUs();
    E = 0;
}

//寫數據
void writeData(uchar dat)
{
    wait();
    RS = 1;
    RW = 0;
    E = 0;
    delayUs();
    LCD_DATA = dat;
    delayUs();
    E = 1;
    delayUs();
    E = 0;
}

//初始化LCD
void init()
{
//    PSB = 1; //并口方式
   delayMs(50);
    writeCmd(0x30); //基本指令, 擴充指令為34H
    delayMs(50);
    writeCmd(0x0c); //顯示開, 關光標
    delayMs(50);
    writeCmd(0x01); //清屏
    delayMs(50);
	delayMs(50);
}

void setPosition(uchar x, uchar y)
{
    uchar p;
    switch(x%4)
    {
        case 0: p = 0x80; break; //第一行開始地址
        case 1: p = 0x90; break; //第二行
        case 2: p = 0x88; break; //第三行
        case 3: p = 0x98; break; //第四行
    }
    p += y;
    writeCmd(p);
}

void writeString(uchar * str)
{
    uchar i = 0;
    while(str[i] != '\0')
    {
        writeData(str[i++]);
    }
}

/**//***************************LCD12864***************************************/

void main()
{
    //先關閉數碼管, 使兩個鎖存器鎖存, 因開了數碼管, USB電壓驅動不夠, 將無法使LCD正常工作
    //dula = wela = 0;
    init();
    setPosition(0, 0);
    writeString(datas1);
    setPosition(1, 0);
    writeString(datas2);
    setPosition(2, 0);
    writeString(datas3);
    setPosition(3, 0);
    writeString(datas4);
    while(1);
}