C语言单片机开发精确延时

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1、这是C程序：#include#include#include#defineucharunsignedchar#definetempintDBYTE[0X30]#definetempdfDBYTE[0X31]ucharcodetab[]={0XC0,0XF9,0XA4,0XB0,0X99,0X92,0X82,0XF8,0X80,0X90};sbitdat="P1"^4;voidset_ds18b20();              //初始化DS18B20子程序voidget

2、_temperature();          //获得温度子程序voidread_ds18b20();             //读DS18B20子程序voidwrite_ds18b20(ucharcommand);//向DS18B20写1字节子程序voiddelayms(ucharcount);       //延时count毫秒子程序voiddisp_temp();                //显示温度子程序voidmain(){    EA="0";                       //禁止中断    

3、SP="0x60";                    //设置堆栈指针    while(1)    {        get_temperature();      //获得温度        disp_temp();            //显示温度    }}voidset_ds18b20(){   while(1)   {       uchardelay,flag;       flag="0";       dat="0";                   //数据线置低电平       delay="250

4、";       while(--delay);          //低电平保持500us       dat="1";                   //数据线置高电平       delay="30";       while(--delay);          //低电平保持60us       while(dat==0)            //判断DS18B20是否发出低电平信号       {           delay="120";           //DS18B20响应，延时240us      

5、     while(--delay);           if(dat)              //DS18B20发出高电平初始化成功，返回           {               flag="1";          //DS18B20初始化成功标志               break;           }       }       if(flag)                 //初始化成功，再延时480us       {           delay="240";           wh

6、ile(--delay);           break;       }   }}voidget_temperature()           //温度转换、获得温度子程序{   set_ds18b20();               //初始化DS18B20   write_ds18b20(0xcc);         //发跳过ROM匹配命令   write_ds18b20(0x44);         //发温度转换命令   disp_temp();                 //显示温度，等待转换结束，大于60

7、0ms   set_ds18b20();   write_ds18b20(0xcc);         //发跳过ROM匹配命令   write_ds18b20(0xbe);         //发出读温度命令   read_ds18b20();              //将读出的温度数据保存到tempint和tempdf处}voidread_ds18b20(){   uchardelay,i,j,temp,temph,templ;   j="2";                         //读2位字节数据   do 

8、  {   for(i=8;i>0;i--)             //一个字节分8位读取   {       temp>>=1;                //读取1位右移1位       dat="0";