8051单片机实现液晶时钟代码解析

#include<reg51.h>
#include <intrins.h>
#define uint  unsigned int
#define uchar  unsigned char
typedef unsigned char  U8;       /* defined for unsigned 8-bits integer variable    无符号8位整型变量  */
typedef signed   char  S8;       /* defined for signed 8-bits integer variable    有符号8位整型变量  */
typedef unsigned int   U16;      /* defined for unsigned 16-bits integer variable    无符号16位整型变量 */

uchar code table[]="TEMP:00  RH:00% ";
uchar code table1[]="   00:00:00 ";
sbit ce=P2^7;
sbit rs=P2^0;
sbit rw=P2^1;
sbit e=P2^2;
sbit cs1=P2^3;
sbit cs2=P2^4;
sbit rst=P2^5;
sbit no=P2^6 ;
//----------------------------------------------//
//----------------定义区--------------------//
//----------------------------------------------//
U8  U8FLAG;
U8  U8count,U8temp;
U8  U8T_data_H,U8T_data_L,U8RH_data_H,U8RH_data_L,U8checkdata;
U8  U8T_data_H_temp,U8T_data_L_temp,U8RH_data_H_temp,U8RH_data_L_temp,U8checkdata_temp;
U8  U8comdata;    
U8  indata[5];
U8  count, count_r=0;
U16 U16temp1,U16temp2;

uchar num,aa,shi,fen,miao,ri,yue,a;
uint nian;
void delay(uint z)
{
uint x,y;
for(x=z;x>0;x--)
for(y=114;y>0;y--);
}
void delayus(uint a)
{
uchar b;

for(b=a;b>0;b--);

}
void COM();
void cewen()
{
 //主机拉低18ms 
ce=0;      
delay(18);
ce=1;
//总线由上拉电阻拉高 主机延时20us    
delayus(2);
//主机设为输入 判断从机响应信号
ce=1;  
//判断从机是否有低电平响应信号 如不响应则跳出，响应则向下运行
 if(!ce)  
{
U8FLAG=2;////////////////////////////////////////////////////