#define uchar unsigned char
#define uint unsigned int

sbit dula = P2^6;
sbit wela = P2^7;
//SCM12864-05端口定义
#define LCD_DATA P0 //数据口
sbit RS = P3^5; //并行的指令/数据选择信号, H数据, L命令
sbit RW = P3^6; //并行读写选择信号, H读, L写
sbit E = P3^4; //并行使能端, H有效, L无效
sbit PSB = P3^7; //并/串接口选择, H并,L串
sbit RET = P3^3; //复位, L有效

uchar code datas1[] = {"广东工业大学"};
uchar code datas2[] = {"自动化学院2004级"};
uchar code datas3[] = {"网络工程 (4)班"};
uchar code datas4[] = {"fengmk2@gmail.com"};

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

//检测LCD是否处于忙状态, 若忙返回1, 空闲返回0
bit checkBusy()
{
    bit busy;
    RS = 0;
    RW = 1;
    E = 1;
    delayUs();
    busy = (bit)(LCD_DATA&0x80);
    E = 0;
    return busy;
}

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

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

//写数据
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
    writeCmd(0x30); //基本指令, 扩充指令为34H
    delayMs(10);
    writeCmd(0x0c); //显示开, 关光标
    delayMs(10);
    writeCmd(0x01); //清屏
    delayMs(10);
}

void setPosition(uchar x, uchar y)
{
    uchar p;
    switch(x%4)
    {
        case 0: p = 0x80; break; //第一行开始地址
        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()
{
    //先关闭数码管, 使两个锁存器锁存, 因开了数码管, USB电压驱动不够, 将无法使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);
}