128*64 LCD screen (ST7920) C51 driver

/**************************
 Resources used by the file
1. Port: P0.0, P0.1
2. Call delay_ms function
******************************/
#define TIME 1
#define display_TIME 1000

sbit CS=P1^0; //Chip select
sbit SCLK=P0^0; //Clock
sbit STD=P0^1; //Data
//sbit LCD_ON=P0^2; //Backlight switch

uchar code AC_TABLE[]={
0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87, //The first line of Chinese characters
0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97, //The second line of Chinese characters
0x88,0x89,0x8a,0x8b,0x8c,0x8d,0x8e,0x8f, //The third line of Chinese characters
0x98,0x99,0x9a,0x9b,0x9c,0x9d,0x9e,0x9f, //The fourth line of Chinese characters
};
/******************************
 Serial transmission of one byte of data
******************************/
void SendByte(uchar dat)
{
 uchar i;
   for(i=0;i<8;i++)
   {
     SCLK=0; //SCLK=0;
     if(dat&0x80)
  STD=1; //STD=1;
     else STD=0; //STD=0;   
     SCLK=1; //SCLK=1;
     dat=dat<<1;     
   }
}
/***************************
  Write control command
***************************/
void SendCMD(uchar dat)
{ 
   CS=1; //CS=1;
   SendByte(0xF8); //11111,00,0 RW=0,RS=0 synchronization flag, send instruction from CPU to LCD 
   SendByte(dat&0xF0); //high four bits
   SendByte((dat&0x0F)<<4);//low four bits
   CS=0; //CS=0;
}
/***************************
 Write display data or single-byte character
***************************/
void SendDat(uchar dat)
{
   CS=1; //CS=1; 
   SendByte(0xFA); //11111,01,0 RW=0,RS=1
   SendByte(dat&0xF0); //High four bits
   SendByte((dat&0x0F)<<4);//Low four bits     
   CS=0; //CS=0;
}
/***************************
 Clear the Chinese characters displayed on the screen
***************************/
void clear_LCD(void)
{
   SendCMD(0x01); //0000,0001 Clear DDRAM
   delay_ms(TIME); 

   SendCMD(0x34); //Extended instruction, allow graphic displaySendCMD
   (0x30); //Basic instruction set bit2, bit1, bit0 in bit2 control
}
/***************************
 Initialize LCM
*******************************/
void init_lcm(void)
{
   CS=0; //CS=0;
   delay_ms(TIME); 
   SendCMD(0x30); //Basic instruction set//bit2, bit1, bit0 in bit2 controlSendCMD
   (0x0C); //0000,1100 Overall display, cursor off, cursor position off
   SendCMD(0x01); //0000,0001 Clear DDRAM
   delay_ms(TIME); 
}
/****************************
   Display picture 128*64
****************************/
void display_picture(uchar *biao)
{
 uchar x,y,i,j,k;
 x=0x80;
 SendCMD(0x34); //Turn off the image display
  for(k=0;k<2;k++)
 { 
  y=0x80;
     for(j=0;j<32;j++)
  {
   SendCMD(y);
           SendCMD(x);
           for(i=0;i<16;i++)
   {
     SendDat(*biao++);   
   }
   y++;
  }
  x=0x88;
 }
  SendCMD(0x36); //Turn on the image display
}
/****************************
   Display the string on the entire screen
****************************/
void display(uchar *str)
{  
 uchar i,k=0;
    while(*str!='\0')
    { 
    if(k==0)SendCMD(0x80);
    else if(k==16)SendCMD(0x90);
    else if(k==32)SendCMD(0x88); 
    else if(k==48)SendCMD(0x98);
    k++;
  if(k==65)
  { 
   k=0;
   for (i=0;i<49;i++)
     {
      str--;
     }
   delay_ms(display_TIME); 
   clear_LCD();
    }
      SendDat(*str++); 
    }
} 
/****************************
   Display the string at the specified position
****************************/
void display_char(uchar row,uchar col,uchar *puts)
{
 bit flag=0;
 SendCMD(0x30); //8BitMCU, basic instruction setwhile
    (*puts != '\0') //Judge whether the string is displayed
    {
     if(col==8) //Judge line break
        { //If not judged, automatically from the first row to the third rowcol
         =0;
            row++;
        }
        if(row==4)
        { 
         row=0; //One screen is displayed and returns to the upper left corner of the screen
        }             
        if(!flag)SendCMD(AC_TABLE[8*row+col]); //Send position commandSendDat
        (*puts++); //A Chinese character needs to be written twiceif
        (flag)col++;
  flag=~flag;
  }
}