51单片机在做DS1302时钟时，往1302写一个字数据时为什么要把RST引脚拉高？拉高了不是不能通信了吗？

能够调通的代码！
#include
#include

sbit SCK=P3^6;
sbit SDA=P3^4;
sbit RST=P3^5;
/*复位脚*/
#define RST_CLR RST=0/*电平置低*/
#define RST_SET RST=1/*电平置高*/

/*双向数据*/
#define IO_CLR SDA=0/*电平置低*/
#define IO_SET SDA=1/*电平置高*/
#define IO_R SDA/*电平读取*/

/*时钟信号*/
#define SCK_CLR SCK=0/*时钟信号*/
#define SCK_SET SCK=1/*电平置高*/

#define ds1302_sec_add 0x80 //秒数据地址
#define ds1302_min_add 0x82 //分数据地址
#define ds1302_hr_add 0x84 //时数据地址
#define ds1302_date_add 0x86 //日数据地址
#define ds1302_month_add 0x88 //月数据地址
#define ds1302_day_add 0x8a //星期数据地址
#define ds1302_year_add 0x8c //年数据地址
#define ds1302_control_add 0x8e //控制数据地址
#define ds1302_charger_add 0x90
#define ds1302_clkburst_add 0xbe

unsigned char time_buf1[8] = {20,9,3,13,18,51,00,6};//空年月日时分秒周
unsigned char time_buf[8] ;//空年月日时分秒周
/*向DS1302写入一字节数据*/
void ds1302_write_byte(unsigned char addr, unsigned char d) {

unsigned char i;
RST_SET; /*启动DS1302总线*/

/*写入目标地址：addr*/
addr = addr & 0xFE;/*最低位置零*/
for (i = 0; i < 8; i ++) {

if (addr & 0x01) {
IO_SET;
}
else {
IO_CLR;
}
SCK_SET;
SCK_CLR;
addr = addr >> 1;
}

/*写入数据：d*/
for (i = 0; i < 8; i ++) {

if (d & 0x01) {
IO_SET;
}
else {
IO_CLR;
}
SCK_SET;
SCK_CLR;
d = d >> 1;
}
RST_CLR; /*停止DS1302总线*/
}

/*从DS1302读出一字节数据*/unsigned char ds1302_read_byte(unsigned char addr) {
unsigned char i;
unsigned char temp;
RST_SET; /*启动DS1302总线*/

/*写入目标地址：addr*/
addr = addr | 0x01;/*最低位置高*/
for (i = 0; i < 8; i ++) {

if (addr & 0x01) {
IO_SET;
}
else {
IO_CLR;
}
SCK_SET;
SCK_CLR;
addr = addr >> 1;
}

/*输出数据：temp*/
for (i = 0; i < 8; i ++) {
temp = temp >> 1;
if (IO_R) {
temp |= 0x80;
}
else {
temp &= 0x7F;
}
SCK_SET;
SCK_CLR;
}

RST_CLR; /*停止DS1302总线*/
return temp;
}

/*向DS302写入时钟数据*/
void ds1302_write_time(void) {

unsigned char i,tmp;
for(i=0;i<8;i++){ //BCD处理
tmp=time_buf1[i]/10;
time_buf[i]=time_buf1[i]%10;
time_buf[i]=time_buf[i]+tmp*16;
}
ds1302_write_byte(ds1302_control_add,0x00); //关闭写保护
ds1302_write_byte(ds1302_sec_add,0x80); //暂停
ds1302_write_byte(ds1302_charger_add,0xa9); //涓流充电
ds1302_write_byte(ds1302_year_add,time_buf[1]); //年
ds1302_write_byte(ds1302_month_add,time_buf[2]); //月
ds1302_write_byte(ds1302_date_add,time_buf[3]); //日
ds1302_write_byte(ds1302_day_add,time_buf[7]); //周
ds1302_write_byte(ds1302_hr_add,time_buf[4]); //时
ds1302_write_byte(ds1302_min_add,time_buf[5]); //分
ds1302_write_byte(ds1302_sec_add,time_buf[6]); //秒
ds1302_write_byte(ds1302_day_add,time_buf[7]); //周
ds1302_write_byte(ds1302_control_add,0x80); //打开写保护
}

/*从DS302读出时钟数据*/
void ds1302_read_time(void) {
unsigned char i,tmp;
time_buf[1]=ds1302_read_byte(ds1302_year_add); //年
time_buf[2]=ds1302_read_byte(ds1302_month_add); //月
time_buf[3]=ds1302_read_byte(ds1302_date_add); //日
time_buf[4]=ds1302_read_byte(ds1302_hr_add); //时
time_buf[5]=ds1302_read_byte(ds1302_min_add); //分
time_buf[6]=(ds1302_read_byte(ds1302_sec_add))&0x7F;//秒
time_buf[7]=ds1302_read_byte(ds1302_day_add); //周

for(i=0;i<8;i++){ //BCD处理
tmp=time_buf[i]/16;
time_buf1[i]=time_buf[i]%16;
time_buf1[i]=time_buf1[i]+tmp*10;
}
}

/*DS302初始化函数*/
void ds1302_init(void) {

RST_CLR; /*RST脚置低*/
SCK_CLR; /*SCK脚置低*/

}