为什么Proteus仿真12864的时候屏幕会是黑色的呢？

程序如下：
#include
#define uchar unsigned char
#define uint unsigned int

sbit cs1=P2^0;
sbit cs2=P2^1;
sbit rs=P2^2;
sbit rw=P2^3;
sbit en=P2^4;

void checkbusy() //忙检测
{
rs=0;
rw=1;
en=1;
P0=0x00;
while(P0&0x80); //检测P0^7是否为0
en=0;
}

void writecom(uchar com)
{
checkbusy();
rs=0; //写指令
rw=0;
P0=com;
en=1; //在EN下降沿写入数据和指令
en=0;
}

void writedata(uchar date)
{
checkbusy();
rs=1; //写数据
rw=0;
P0=date;
en=1;
en=0;
}

void setscreen(uchar n)
{
switch(n)
{
case 0:cs1=0;cs2=0;break; //选择2屏
case 1:cs1=0;cs2=1;break; //选择左屏
case 2:cs1=1;cs2=0;break; //选择右屏
default:break;
}
}

void clear(uchar n)
{
uchar i,j;
setscreen(n); //选择要清除的屏n为0,1
for(i=0;i<8;i++)
{
writecom(0xb8+i); //要清除的页：1~8页
writecom(0x40); //每页都从第1列开始，共64列
for(j=0;j<64;j++)
writecom(0); //写入0，列地址指针会自动加1
}
}

void LCDinit()
{
checkbusy();
setscreen(0); //0为2屏，1为左屏，2为右屏
writecom(0x3f); //0x3e为关闭屏幕，0x3f为开启
writecom(0xb8); //设置首页，共8页
writecom(0xc0); //设置首行，共64行
writecom(0x40); //设置首列，共64列

clear(0); //清2屏
}

void show(uchar page,uchar column,uchar *str)
{
uchar i,j;
for(i=0;i<2;i++) //一个汉字要2页
{
writecom(0xb8+page+i); //page=0,2,4,6
writecom(0x40+column); //column=0~63
for(j=0;j<16;j++)
writedata(str[i*16+j]); //i=0为上半页数据，i=1为下半页，j表示行
}
}
uchar code dong[]=
{
0x00,0x08,0x88,0x48,0x28,0x18,0x0F,0xE8,0x08,0x08,0x08,0x08,0x08,0x08,0x00,0x00,
0x00,0x20,0x11,0x09,0x05,0x41,0x81,0x7F,0x01,0x01,0x05,0x09,0x11,0x20,0x00,0x00
};

void main()
{
LCDinit();
setscreen(1);
show(0,3*16,dong);
setscreen(2);
show(0,0*16,dong);
while(1);
}

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