日历时钟DS12887/146818的C51源程序 
#define uchar unsigned char
#define uint unsigned int
#include <reg52.h>
#include <stdio.h>
#include <absacc.h>
#include <math.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>

#define P128870 XBYTE[0xa000]
#define P128871 XBYTE[0xa001]
#define P128872 XBYTE[0xa002]
#define P128873 XBYTE[0xa003]
#define P128874 XBYTE[0xa004]
#define P128875 XBYTE[0xa005]
#define P128876 XBYTE[0xa006]
#define P128877 XBYTE[0xa007]
#define P128878 XBYTE[0xa008]
#define P128879 XBYTE[0xa009]
#define P12887a XBYTE[0xa00a]
#define P12887b XBYTE[0xa00b]
#define P12887c XBYTE[0xa00c]
#define P12887d XBYTE[0xa00d]
#define P12887e XBYTE[0xa00e]
#define P12887f XBYTE[0xa00f]

void setup12887(uchar *p);
void read12887(uchar *p);
void start12887(void);

void setup12887(uchar *p)  //设置系统时间
{
    uchar i;
    i=P12887d;
    P12887a=0x70;    P12887b=0xa2;    P128870=*p++;    P128871=0xff;    P128872=*p++;
    P128873=0xff;    P128874=*p++;    P128875=0xff;    P128876=*p++;    P128877=*p++;
    P128878=*p++;    P128879=*p++;    P12887b=0x22;    P12887a=0x20;
    i=P12887c;
}
void read12887(uchar *p)   //读取系统时间
{
    uchar a;
    do{ a=P12887a; } while((a&0x80)==0x80);
    *p++=P128870; *p++=P128872; *p++=P128874; *p++=P128876;
    *p++=P128877; *p++=P128878; *p++=P128879;
}
void start12887(void)      //启动时钟
{
    uchar i;
    i=P12887d;
    P12887a=0x70;    P12887b=0xa2;    P128871=0xff;    P128873=0xff;    P128875=0xff;
    P12887b=0x22;    P12887a=0x20;
    i=P12887c;
}