一、DS1302时钟模块
现在流行的串行时钟电路很多，如DS1302、 DS1307、PCF8485等。这些电路的接口简单、价格低廉、使用方便，被广泛地采用。
DS1302 是美国DALLAS公司推出的一种高性能、低功耗、带RAM的实时时钟电路，它可以对年、月、日、周、时、分、秒进行计时，具有闰年补偿功能，工作电压为2.0V～5.5V。采用三线接口与CPU进行同步通信，并可采用突发方式一次传送多个字节的时钟信号或RAM数据。DS1302内部有一个31×8的用于临时性存放数据的RAM寄存器。DS1302是DS1202的升级产品，与DS1202兼容，但增加了主电源/后备电源双电源引脚，同时提供了对后备电源进行涓细电流充电的能力，该芯片采用普通32.768kHz晶振，DS1302 工作时功耗很低保持数据和时钟信息时功率小于1mW。
图1 DS1302时钟模块实物图
图2 DS1302时钟模块封装
表1 DS1302芯片引脚功能介绍表
| VCC1 | 后备电源 |
| GND | 电源地 |
| VCC2 | 工作电源 |
| X1 | 晶振32.768kHz输入 |
| X2 | |
| SCLK | 时钟信号 |
| I/O | 数据输入输出 |
| RST | 复位信号|片选信号 |
DS1302时钟模块的引脚功能介绍如表1所示，而时序不再做陈述，需要再自行查找资料。
二、DS1302时钟模块驱动代码
1.头文件
#ifndef _DS1302_H_#define _DS1302_H_#include "STC15F2K60S2.h"#ifndef UINT8#define UINT8 unsigned char#endif#ifndef DS1302_READ_BURST#define DS1302_READ_BURST 0xBF#endif#ifndef DS1302_WRITE_BURST#define DS1302_WRITE_BURST 0xBE#endifsbit DS1302_IO = P1^4;sbit DS1302_RST = P1^5;sbit DS1302_SCLK = P1^3;extern UINT8 xdata time[9];extern UINT8 xdata date[11];extern UINT8 xdata current_day[2];//声明全局变量void DS1302_WriteByte(UINT8 data_byte);//向ds1302写一个字节void DS1302_ReadByte(UINT8 *data_byte);//从ds1302读一个字节void DS1302_Start();//操作起始信号void DS1302_Over();//操作结束信号void DS1302_ClearWriteProtection();//清除写保护void DS1302_SetWriteProtection();//设置写保护void DS1302_SetTime(UINT8 *ds1302_set_buffer);//设置ds1302的时间void DS1302_ReadTime(UINT8 *ds1302_build_buffer);//读取ds1302的时间void Time_Build();//系统从ds1302读取时间void Time_Set();//系统向ds1302设置时间void Time_Init();//系统时间初始化#endif2.主程序
#include "ds1302.h"void DS1302_WriteByte(UINT8 data_byte)//向ds1302写一个字节{UINT8 i;for (i=0;i<8;i++){DS1302_IO = data_byte & 0x01;DS1302_SCLK = 1;data_byte >>= 1;DS1302_SCLK = 0;}}void DS1302_ReadByte(UINT8 *data_byte) //从ds1302读一个字节{UINT8 i;for (i=0;i<8;i++){ *data_byte >>= 1;if (DS1302_IO){*data_byte |= 0x80;}DS1302_SCLK = 1;DS1302_SCLK = 0;}}void DS1302_Start()//操作起始信号{DS1302_RST = 0;DS1302_SCLK = 0;DS1302_RST = 1;}void DS1302_Over()//操作结束信号{DS1302_IO = 0;DS1302_RST = 0;}void DS1302_ClearWriteProtection()//清除写保护{DS1302_Start();DS1302_WriteByte(0x8E);DS1302_WriteByte(0x00);DS1302_Over();}void DS1302_SetWriteProtection()//设置写保护{DS1302_Start();DS1302_WriteByte(0x8E);DS1302_WriteByte(0x80);DS1302_Over();}void DS1302_SetTime(UINT8 *ds1302_set_buffer)//突发模式下设置时间{UINT8 i;DS1302_ClearWriteProtection();DS1302_Start();DS1302_WriteByte(DS1302_WRITE_BURST);for (i=0; i<7; i++){DS1302_WriteByte(ds1302_set_buffer[i]);}DS1302_WriteByte(0x80);//突发模式一次要写8个字节，第八个字节是写保护字节DS1302_Over();}void DS1302_ReadTime(UINT8 *ds1302_read_buffer)//突发模式下读取时间{UINT8 i,Temp;DS1302_ClearWriteProtection();DS1302_Start();DS1302_WriteByte(DS1302_READ_BURST);for (i=0; i<7; i++){DS1302_ReadByte(ds1302_read_buffer+i);}DS1302_ReadByte(&Temp);//突发模式一次读8个字节，最后一字节读出来没用DS1302_Over();DS1302_SetWriteProtection();}void Time_Build()//读取时间后转换成需要的格式{UINT8 xdata ds1302_build_buffer[7];DS1302_ReadTime(ds1302_build_buffer);time[7] = (ds1302_build_buffer[0]&0x0f)+'0';time[6] = ((ds1302_build_buffer[0]&0x70)>>4)+'0';time[4] = (ds1302_build_buffer[1]&0x0f)+'0';time[3] = ((ds1302_build_buffer[1]&0x70)>>4)+'0';time[1] = (ds1302_build_buffer[2]&0x0f)+'0';time[0] = ((ds1302_build_buffer[2]&0x30)>>4)+'0';date[9] = (ds1302_build_buffer[3]&0x0f)+'0';date[8] = ((ds1302_build_buffer[3]&0x30)>>4)+'0';date[6] = (ds1302_build_buffer[4]&0x0f)+'0';date[5] = ((ds1302_build_buffer[4]&0x10)>>4)+'0';date[3] = (ds1302_build_buffer[6]&0x0f)+'0';date[2] = ((ds1302_build_buffer[6]&0xf0)>>4)+'0';}void Time_Set()//将时间转化为对应格式存入ds1302{UINT8 xdata ds1302_set_buffer[7];ds1302_set_buffer[0] = time[7]-'0';ds1302_set_buffer[0] |= ((time[6]-'0')&0x07)<<4;ds1302_set_buffer[1] = time[4]-'0';ds1302_set_buffer[1] |= ((time[3]-'0')&0x07)<<4;ds1302_set_buffer[2] = time[1]-'0';ds1302_set_buffer[2] |= ((time[0]-'0')&0x03)<<4;ds1302_set_buffer[3] = date[9]-'0';ds1302_set_buffer[3] |= ((date[8]-'0')&0x03)<<4;ds1302_set_buffer[4] = date[6]-'0';ds1302_set_buffer[4] |= ((date[5]-'0')&0x01)<<4;ds1302_set_buffer[6] = date[3]-'0';ds1302_set_buffer[6] |= ((date[2]-'0')&0x0f)<<4;ds1302_set_buffer[5] = 0x01;DS1302_SetTime(ds1302_set_buffer);}void Time_Init()//开机时间初始化{Time_Build();current_day[0] = date[8];current_day[1] = date[9];//保存当前日期，用于检测日期变化}三、DS1302时钟模块与USRAT HMI通信
uchar a=0,b=0,c=0,d=0,e=0,f=0;/**********显示时间**********/ a = date[2]; //发送年数据b = date[3];c = date[5]; //发送月数据d = date[6];e = date[8]; //发送日数据f = date[9];write_txt("t0.txt="); //发送文本write_COM(34); //双引号write_COM(a);write_COM(b);write_COM(34);write_END(); //结束符 write_txt("t1.txt="); //发送文本write_COM(34); //双引号write_COM(c);write_COM(d);write_COM(34);write_END(); //结束符 write_txt("t2.txt="); //发送文本write_COM(34); //双引号write_COM(e);write_COM(f);write_COM(34);write_END(); //结束符 a = time[0]; //发送时数据b = time[1];c = time[3]; //发送分钟数据d = time[4];e = time[6]; //发送秒钟数据f = time[7];write_txt("t3.txt="); //发送文本write_COM(34); //双引号write_COM(a);write_COM(b);write_COM(34);write_END(); //结束符 write_txt("t4.txt="); //发送文本write_COM(34); //双引号write_COM(c);write_COM(d);write_COM(34);write_END(); //结束符write_txt("t5.txt="); //发送文本write_COM(34); //双引号write_COM(e);write_COM(f);write_COM(34);write_END(); //结束符write_txt("t9.txt="); //发送文本write_COM(34);if(week==1) //发送星期数据write_txt("一");if(week==2)write_txt("二");if(week==3)write_txt("三");if(week==4)write_txt("四");if(week==5)write_txt("五");if(week==6)write_txt("六");if(week==7)write_txt("日"); write_COM(34);write_END();
